Biology ICSE Keypoints

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) ChristSc hoolRoa d,Dharmar amCol legeP. O.,Bangal ore5600 29,Karnat aka

Cell Division – Keypoints 1. Cell division is a method of producing two or more new daughter cells from a single mother cell. 2. Significance of cell division - Continuity of life depends on cell division. Cell division also helps in  Growth  Replacement  Repair  Reproduction of an organism. 3. Cell division types – Amitosis, Mitosis, Meiosis 4. Amitosis   

Simple common process of cell division. Occurs in prokaryotic cells. Nucleus divides several times without the division of cytoplasm.

5. Mitosis   

Cell divides into two daughter cells. Each having the same chromosome number and genetic constitution. Ensures, all the cells of an individual is genetically identical to each other.

6. Meiosis  Cell divides into 4 daughter cells.  Each having only half the number of chromosomes.  Shows genetic variation.  Ensures the production of gametes.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 1

7. The sequence of events including duplication of chromosomes (DNA), synthesis of other cell constituents, growth and division that a cell undergoes from the time of its formation up to its division into daughter cells is called CELL CYCLE.

8. A cell cycle consists of two phases.  Interphase – Resting phase (Non-dividing phase) 

Metabolically very active. Mitotic phase – Divisional phase (Dividing phase)

9. Interphase     

A preparatory phase. Non-dividing phase. Cell grows in to its maximum size. Chromosomes duplication occurs. Growth phase between two successive divisions of the cell.

10.Interphase is divided into 3 phases. 

G1 – First growth (gap) phase/ Post mitotic phase.



S – Synthesis phase.  G2 - Second growth (gap) phase/ Pre mitotic phase.

11.

Interphase is the non-dividing preparatory phase of cell cycle

during which a cell grows in size and duplication of chromosome take place. CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 2

12. G1 – First growth (Gap) phase/ Post mitotic phase.(10 hrs)

Longest phase of Interphase. Also called first gap phase. Preparatory phase for the oncoming cell division. Major events   

Synthesis of RNA and proteins. Volume of cytoplasm increases. Cell organelles increases in number.

13. S – Synthesis phase.(8hrs) 

Duplication of chromatin fibres by the synthesis of histones and DNA materials. ( So that they are equally distributed among the daughter cells during cell division)

14. G2 - Second growth phase/ Pre mitotic phase.(5hrs)  

Synthesis ofof RNA and proteins continues. Replication centrosomes.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 3

15. Mitotic phase (M phase) 1hr.   

It is the phase of cell division - Dividing phase. Studied in two divisions. Division of nucleus (Karyokinesis) and Division of cytoplasm (Cytokinesis).

MITOSIS

Occurs in somatic cells. For growth, repair, replacement and asexual reproduction in unicellular organisms. Maintain the chromosome number even after the division of the cell. Called Equational division. Produce two daughter cells. Each having the same chromosome number and genetic constitution. Ensures, all the cells of an individual is genetically identical to each other Maintain the diploid condition of the cell. A cell division in which two identical daughter cells are formed by the division of one parent cell.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 4

1. Mitosis is a type of cell division that take place in somatic cells, during which the cell divides into two daughter cells, each containing the same and similar number of chromosomes as present in the parent cell. 2. Karyokinesis occurs in 4 phases:

Prophase Metaphase Anaphase Telophase 3.

Prophase Longest and most complex phase. Lasts about 50 min. Major Events – Early Prophase

Condensation of chromatin fibres. Nuclear membrane starts gradually disappearing. Nucleolus also starts disappearing. Centrosomes with centrioles start migrate to the opposite poles of the cell. CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 5

A number of fine radiating fibre like structures arise from the centrioles called Astral rays Centrioles along with astral rays are called Asters Asters get extended between the centrioles which move towards the opposite poles of the cell. The very fine proteinaceous thread like structures that are developed between the two asters are called Spindle fibres. Asters along with spindle fibres are called spindle apparatus /mitotic apparatus. In animals spindle apparatus /mitotic apparatus formed as amphiastral – Formed from asters. In plants spindle apparatus /mitotic apparatus formed (without asters) as anastral – Formed from cytoplasmic strands called microtubules. Late prophase  

 

Nuclear membrane and nucleolus disappeared. Chromosomes can be seen prominently (as two longitudinal chromatids joined by the centromrere). Centrioles are reached the opposite poles with spindle fibres. Chromosomes get attached to the spindle fibers with the help of the centrosome.

4. Metaphase  

Simple, Short, 2-10 min Chromosomes get aligned at the equator of the cell.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 6

Centromere Chromosome

Spindle fibres

 

Centromeres lie on the equator and the arms face towards the poles. The arrangement of chromosomes on the equator in such a way that their centromeres lie on the equator and the arms face towards the poles is called

Metaphasic plate/ Equatorial plate. 5. Anaphase  

 

Simple, Short, 2-3 min The centromere of each chromosome divides (longitudinally) into two halves. (Chromatids separated with its own centromere). Each daughter chromosome retains one of the two chromatids. The daughter chromosomes move towards the opposite polesfibres (due to the contraction of spindle & the repelling force developed between them)

6. Telophase   

 

Long, Complex, Reverse of prophase. The daughter chromosomes reach at the opposite poles. Start uncoiling, thinning and elongatingchromatin network. Nuclear membrane and nucleolus reappear. Spindle fibres, astral rays disappear. CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 7

7. Karyokinesis is followed by Cytokinesis. 8. Cytokinesis:

Division of cytoplasm Begins during late Anaphase. Completed soon after the telophase. Different in animal and plant cell. In animal cell:

A furrow or constriction appears in the middle of the cell membrane, parallel to the equator. Deepens towards the centre of the cell - CENTRIPETAL In plant cell:

A cell plate is formed at the centre of the equator. Extends towards the periphery – CENTRIFUGAL

Differences between mitosis in plant cell and animal cell. Animal cell

Cytokinesis

Plant cell

By the appearance of furrow or constriction.

By the formation of cell plate.

It is Centripetal –Proceeds from periphery towards the centre.

It is Centrifugal -Proceeds from centre towards the periphery.

Asters

Formed from the centrioles. (Due to the presence of centrosome)

Not formed (Centrosome & centrioles are absent)

Spindle fibres

Formed as amphiastral – Formed from asters.

Formed as anastral – Formed from microtubules

Occur

Most tissues throughout the body.

Mainly at the growing tips.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 8

9. Significance of Mitosis:

Keeps the number of chromosomes constant in the daughter cells.(genetic stability) Responsible for the growth of an organism.(increases the body size) Helps in repairing damaged or wounded tissues. Helps in the replacement of old and dead cells – lost during normal wear and tear. Method of reproduction in unicellular organism – Asexual reproduction. 10.

Meiosis (Reduction division) Produces sex cells or gametes. Occurs in the reproductive organs – reproductive cells. (Testis – Sperm, Ovary – Ova/Egg in animals & Anthers – pollen grains, Ovary – Ovules in flowering plants) Occurs in diploid cell – A cell which has full set of chromosomes corresponding to the chromosome number of that particular species is termed as diploid cell (2n). Cell divides into 4 daughter cells. Each having only half the number of chromosomes. (Haploid cell) – A cell which has only half the number of chromosomes corresponding to the chromosome number of that particular species is termed as haploid cell (n). Meiosis is a reduction division as the chromosome number is reduced to half in the daughter cells when compared to the parent cell. Meiosis is completed in successive cell division – Meiosis I and Meiosis II. Meiosis I – Reduction division. Meiosis II – Equational division CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 9

Meiosis I is called Reduction division because the number of chromosomes in this type of division is reduced to half in the daughter cells. Meiosis I is followed by Meiosis II. Meiosis II is called Equational division because it is just similar to the mitosis. 11. Meiosis is a type of cell division in which the cell undergoes two successive cell division producing four daughter cells, each containing half the number of chromosomes as compared to the parent cell. 12.

Meiosis I

Condensation of chromosomes. Homologous chromosomes start to pair up. [A pair or of chromosomes which are similar in size, shape, position of centromere and gene loci is termed as Homologous chromosomes]. A pair of homologous chromosomes is called BIVALENT. The process of pairing up of homologous chromosomes is called SYNAPSIS. The four chromatids of a homologous chromosome or a bivalent are called TETRAD.

Pairs of homologous chromosomes line up on the metaphase plate.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 10

Mutual exchange of genetic material between the non- sister chromatids of the corresponding parts of the homologous chromosomes takes place. This is called CROSSING OVER.

The point at which crossing over occurs where the homologous chromosome remain attached is called CHIASMA (Chiasmata [p])

13.

Significance of Crossing Over:

It results in genetic combination. (Paternal and Maternal chromosomes get mixed up) Provides variation in the progeny. Variations lead to the evolution. 14. The homologous chromosomes separate completely and move towards the opposite poles.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 11

15.

Significance of Meiosis  Helps in the formation of gametes.  Helps to maintain the chromosome number constant generation after generation.  Crossing over helps to produce variations and thus leads to evolution.

CELL DIVISION Key points; Prepared by Ms. Anitha Joseph Page Number: 12

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) ChristSc hoolRoa d,Dharmar amColleg eP.O.,Ba ngalore5 60029,K arnataka

Chromosomes – Notes

1. Chromosomes are highly condensed chromatin materials that carry genes which is responsible for the transmission of hereditary characters from parents to offspring.

2. Non dividing cell - Chromatin network/ chromatin fibres(Not distinct & clear, very long like a network) 3. Dividing cell - Chromosomes (Distinct, short thick & darkly stained structure) 4. Chromatids are the two longitudinal halves of a chromosome. 5. Centromere is the point at which the two chromatids are joined. 6. Function of centromere 

Joins the two chromatids together.



Help the chromosome to get attached to the spindle fibres during cell division.

7. Chromosomes according to the position of centromere:  

Metacentric Submetacentric Acrocentric



Telocentric



8. Metacentric – Centre, Equal arms, V shape.

9. Submetacentric - Slightly away from the centre, one arm is longer than the other, L shape.

CHROMOSOMES Key points; Prepared by Ms. Anitha Joseph Page Number: 1

10. Acrocentric - Near one end of the chromatid, one arm is very long and the other is very short, J shape.

11. Telocentric - At one end, Rod shaped arm, I shape. 12. Chemical constitution of chromosomes:  

60% - Protein – Histones 40% - nucleic acid – DNA (Deoxyribo nucleic acid)

13. DNA (Deoxyribo nucleic acid) 

Very large single molecule - Macromolecule.



Two long parallel strands – polynucleotide strand –complementary.



Composed of a unit – Nucleotide ( structural and functional unit of DNA / Basic component of DNA)

14. Nucleotide -3 parts:   

Phosphate group - P Pentose sugar - S Nitrogen base - NB

15. Nitrogen base – 2 Types: 

Purines – Adenine, guanine



Pyrimidines – Cytosine, Thymine

16. Nitrogen bases are complementary to each other. 

Adenine - Thymine (A – T)



Guanine -

Cytosine (G – C)

CHROMOSOMES Key points; Prepared by Ms. Anitha Joseph Page Number: 2

17. DNA molecule consists of two long parallel polynucleotide complementary strands that wound around each other in the form of a spiral stairs or twisted ladder. So it is called double helical structure. 18. The double helical DNA structure is studied by Rosalind Franklin (1953) and Worked out by Watson and Crick (1953). It is also called Watson and Crick model. 19. A core of 8 histones is surrounded by a DNA molecule form a complex is called a nucleosome.

20. Gene is a specific sequence of nucleotides on a chromosome that encode a particular protein which controls a specific feature/behavior in the body. CHROMOSOMES Key points; Prepared by Ms. Anitha Joseph Page Number: 3

CHRIST SCHOOL (Affiliated to the Council for t he ICSE, New Delhi. Reg. No: KA260/2013) ChristSchoolRoad,DharmaramCollegeP.O.,Bangalore560029,Karnataka

CLASS – X TRANSPIRATION - KEYPOINTS

TRANSPIRATION is the

process by which plants loss water in the form of water vapour from the aerial parts of a plant. KINDS OF TRANSPIRATION 

Stomatal – through stomata (Diffusion)



Cuticular – through cuticle (Evaporation)



Lenticular – through lenticels(Diffusion)

STOMATA (Diagram) 

Minute opening found in between the lower epidermal layer of the leaves.



Large in number (1000-10000/cm3).



Stomata helps in: Transpiration. Exchange of gases i.e. CO2 for photosynthesis and O 2 for respiration.



Stoma is surrounded by two specialized epidermal cells – Guard cells (Kidney / Dumb-bell shaped).



Guard cells control the opening and closing of stomata (Check transpiration).



Guard cells are turgor operated valves i.e. Opening and closing of stomata is regulated by turgidity of guard cells.



Stomatal transpiration is controlled by the plant, by adjusting the size of the stoma, where as it doesn’t happen in cuticular and lenticular transpiration.



More transpiration occurs from the underside of the leaf as more stomata are on the undersurface of the leaf.

REGULATION OF STOMATAL OPENING (diagram) 

Guard cells control the opening and closing of stomata.



Guard cells are highly specialized epidermal cells with chloroplasts which surround the stomata.



The walls of guard cells differentially thickened.



The inner wall facing the aperture (opening) is thick and inelastic; the outer wall on the opposite side is thin and elastic. (Diagram)



When the guard cells become turgid, the cells bugle outward due to thin and elastic outer wall where as the inner wall is pulled inward due to its thick and inelastic nature. This widens the opening (aperture) lying between them and the stoma is opened.



When the guard cells lose their turgidity, their inner wall straightensand stoma is closed.



Transpiration occurs as the stomata are open; it stops when they are closed.



Transpiration is controlled in stomatal transpiration by adjusting the size of the stomata.

THEORIES OF OPENING AND CLOSING OF STOMATA:



Sugar concentration theory (OLD)

Day time guard cells photosynthesize – glucose is produced. Higher glucose level in the guard cells increases their osmotic pressure Hypertonic. Leads to endosmosis (Draw water from the adjoining cells). The guard cells become more turgid. Turgid guard cells open stoma. Night time, Glucose production reduces. Osmotic pressure of guard cells decreases - Hypotonic Guard cells undergo exosmosis. Cells become flaccid (Lose turgidity) Losing turgidity of guard cells close stoma. 

+

K concentration Theory (NEW) 

Day time guard cells photosynthesize – ATP is produced.



ATP is used to uptake K+ ions from adjoining cells to guard cells.



Higher K+ ions level in the guard cells increases their osmotic pressure Hypertonic.



Leads to endosmosis (Draw water from the adjoining cells).



The guard cells become more turgid.



Turgid guard cells open stoma.



Night time, K+ ions leak out of guard cells.



Osmotic pressure of guard cells decreases - Hypotonic



Guard cells undergo exosmosis.



Cells become flaccid (Lose turgidity)



Losing turgidity of guard cells close stoma.

MECHANISM OF STOMATAL TRANSPIRATION (diagram)



Opening and closing mechanism of stomata (turgidity of guard cells) is regulated by the amount of water and solute present in the guard cells.



Root hairs xylem



Water escapes through stomata in the form of water vapors. The entire movement of water in the form of water vapour from the surface of the mesophyll cells into the outside atmosphere results in transpiration.



Cortical cells Mesophyll cells

Root xylem Stem xylem Leaf Intercellular space Atmosphere



In the leaves of plants most of the water travels along the cell wall by imbibitions.



Some amount of water travels through the cell (cell cytoplasm) by osmosis.



From the xylem vessels water moves to mesophyll cells by cell to cell osmosis.



In the leaves a large number of spongy mesophylls are present.



Spongy mesophylls are exposed to numerous intercellular spaces present between them.



Due to the turgidity, turgor pressure developed in the Spongy mesophyll cells



Due to the turgor pressure of the mesophyll cells, some of the water forms a thin film of water on the outer surface of the cells.



The water from this film evaporates into the intercellular space.



The water vapour then diffuses into other connecting intercellular spaces and finally reaches the substomatal spaces(Space exposed to stomata)



The water vapour from the substomatal space moves to outside through open stomata by diffusion. (Water potential of the air in the intercellular spaces of the leaf becomes higher than that of air present outside the leaf).



The loss of water from the leaves creates a suction force in the leaf cells which causes leaf xylem to pull water from stem xylem and root xylem in turn.



The suction force which is developed in the leaf cells due to transpiration is called transpiration pull.



Transpiration pull is one of the most important factor of Ascent of sap

MOVEMENT OF WATER THROUGH A LEAF DURING TRANSPIRATION: (diagram) LEAF XYLEM

Cell wall by imbibitions (Most of the water) Cytoplasm by osmosis (Some of the water) ADJOINING MESOPHYLL CELLS

Turgor pressure due to turgidity OUTER SURFACE OF MESOPHYLL CELLS

Evaporation INTERCELLULAR SPACES & OTHER CONNECTING SPACES

Diffusion SUBSTOMATAL SPACES

Diffusion ATMOSPHERE THROUGH OPEN STOMATA



Cuticle – The waxy layer on the outer surface of the epidermis of leaves.



Greater the thickness of the cuticle, the lesser is the evaporation.



Lenticels – Minute opening on the surface of older parts of stem.



Lenticels never close; they remain open all the time. No cells to guard them and control their size of the opening.



Stomatal transpiration is controlled by the plant, by adjusting the size of the stoma, where as it doesn’t happen in cuticular and lenticular transpiration.



Leaves of some plants wilt during midday and recover in the evening because the rate of transpiration exceeds the rate of absorption; so the cells of plant lose turgidity and get wilted.

FACTORS AFFECTING TRANSPIRATION:



Light intensity - High

Higher rate of transpiration 

Stomata are open. Cloudy days, stomata are partially closed, reduce transpiration.



Temperature – High

Higher rate of transpiration More evaporation 

Velocity of Wind – High

Higher rate of transpiration Water vapour will be swept away faster and does not get saturated outside the leaf. 

Humidity – Low

Higher rate of transpiration Higher the rate of outward diffusion of water vapours.

 



High humidity in the air reduces the rate of outward diffusion of water vapour , thus reduces the transpiration.

 CO2

concentration in the atmosphere– Low

 

Higher rate of transpiration Stomata are open



Higher conc. of CO2 in the atmosphere (over normal 0.03%) causes the closure of stomata, thus reduces the transpiration.



Atmospheric pressure – Low  



Higher rate of transpiration Higher diffusion of water vapour

Atmospheric pressure – High 

Lower rate of transpiration





Lower diffusion of water vapour Water content of leaf – High  



Higher rate of transpiration Stomata are open

Larger surface area of leaf - Higher rate of transpiration



Thick cuticle - Lower rate of transpiration



Less number of stomata - Lower rate of transpiration

ADAPTATIONS TO REDUCE EXCESSIVE TRANSPIRATION :



Sunken stomata - Nerium



Fewer stomata



Narrow leaves - Nerium



Reduced exposed surface – Rolling, twisting, curling, wavy, folded

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Loss of leaves - Changed into spines(Cacti), drooped

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Thick cuticle – Banyan



Stomata located on the lower surface - Dicot



Leaf modifications – Leaf spines(Cacti), phylloclade, Scaly leaves

SIGNIFICANCE OF TRANSPIRATION:



Transpiration helps in absorption of water.



Transpiration provides cooling effect to plant.



Transpiration helps in the distribution of water and mineral salts throughout the plant body.



Transpiration develops extensive root system.



Transpiration affects climate – Brings rain. (Transpiration increases the moisture in the atmosphere and brings rain).



Transpiration pull is responsible for ascent of sap.( Ascent of sap is the upward movement of water through the stem xylem).



The loss of water from the leaf cells develop a tension in these cells i.e. the osmotic pressure of the cells increase and they become hypertonic. This draws water from the cells at the lower levels in a sequential manner (mesophylls leaf xylem



stem xylem

root xylem) cause Ascent of sap.

Ascent of sap favours the absorption of water from the soil by the roots.

TRANSPIRATION IS A PRICE FOR PHOTOSYNTHESIS: 

As the stomata open for allowing CO2 to diffuse in for photosynthesis water vapour escapes. Hence transpiration is incidental to photosynthesis .

GUTTATION is

the loss of water in the form of water droplets through hydathodes of leaves. (Loss water directly in the form of liquid)

Hydathodes are special pore bearing structures located on the margins of the leaves. Hydathodes allow guttation or exudation. CAUSES OF GUTTATION:



Hydrostatic pressure develops inside the leaf due to the high rate of absorption and low rate of transpiration. This forces water moves out of the opening.

Guttation cannot be controlled as transpiration: 

Guttation occurs through hydathodes which are always open, hence cannot be controlled.

A humid environment hampers the transpiration, while the roots continue to absorb water and minerals. This decrease the rate of transpiration & increase the rate of absorption Rate of absorption exceeds the rate of transpiration – Guttation Rate of transpiration exceeds the rate of absorption – Wilting BLEEDING is the exudation of cell sap from the injured part of the plant (Root

pressure causes it) In GUTTATION and BLEEDING, a plant loses water in the Liquid form – water droplets. Transpiration is a necessary process to facilitate gaseous exchange for photosynthesis and respiration.

CHRIST SCHOOL (Affiliated to the Council for t he ICSE, New Delhi. Reg. No: KA260/2013) ChristSchoolRoad,DharmaramCollegeP.O.,Bangalore560029,Karnataka

CLASS – X PHOTOSYNTHESIS- KEYPOINTS

PHOTOSYNTHESIS is

a physiological process by which green plants prepare organic compound – Carbohydrate – using inorganic substances – CO2, H2O in the presence of chlorophyll and light energy. SIGNIFICANCE:  Provides food for all organisms.  Maintain O2 level. CONDITIONS REQUIRED:  Light energy  Chlorophyll pigments RAW MATERIALS REQUIRED:

 CO2  H2O LIGHT ENERGY

 Sun is the main source.  Red and blue lights are more absorbed and most effective for photosynthesis. CHLOROPHYLL PIGMENTS

 The vital plant pigment.  Located in the chloroplasts of plant cells.

STRUCTURE OF A LEAF

STRUCTURE OF CHLOROPLAST

 Oval shaped cell organelle  Bounded by double membrane  Colourless ,living ground substance (Fluid) enclosed by the double membrane

–

STROMA/MATRIX 

Flattened membranous sac like structure in the stroma - THYLAKOID



Pile of thylakoid – GRANUM(s)/GRANA(p)



Interconnection between thylakoids of grana – STROMA LAMELLA/ INTERGRANAL THYLAKOID / FRET

 Chlorophyll pigments are present in the walls of thylakoid.  Chlorophyll pigments are composed of Carbon, Hydrogen, Oxygen, Nitrogen and

Magnesium.  Chlorophyll are of 9 types.  Two most abundant Chlorophyll molecules are Chlorophyll a and Chlorophyll b.  Light is essential for the formation of new chlorophyll molecule.In the absence of

light, new chlorophyll does not form, old chlorophyll get disintegrated. Hence the leaves turn yellow.  Too much light destroys chlorophyll pigment.  The main element which is required for the formation of chlorophyll pigment is

magnesium.  The accessory pigments which help in the transference of light energy to

chlorophyll a are xanthophyll and carotene. CO2  CO2 from the atmosphere, through stomata, by diffusion.

H2O  H2O from soil by imbibition and osmosis. 

MECHANISM OF PHOTOSYNTHESIS  Site of photosynthesis

– Chloroplast of Mesophyll cells in Plant cells.

 TWO PHASES

Light dependent phase (Photochemical phase/Hill reaction) Light independent phase (Biosynthetic phase/ Calvin cycle)  LIGHT DEPENDENT PHASE (PHOTOCHEMICAL PHASE/HILL REACTION)

Site – Grana of the Chloroplast (Thylakoid) Take place only in the presence of light. Mainly occurs in two phases  Activation of chlorophyll  Splitting of water  ACTIVATION OF CHLOROPHYLL

– PROCESS INVOLVED:

Activation of chlorophyll molecules by absorbing light energy as photons(Smallest unit of light energy) The low energy molecules move to a high energy state and emit electron transport chain in chloroplast. The emitted energy is used to split water molecules H 2 and O2 PHOTOLYSIS Light Energy

H2O

H+

+ OH-

OH-

 OH * 4

2H 2O

+

O2

OH- oxidized to O2 and H 2O O2 released during photosynthesis comes from H 2O, not from CO2 . H+ produced by the splitting of H2O molecule is used to reduce NADP – Nicotinamide Adenine Dinucleotide Phosphate ( A low energy compound present in the cell) NADP + 2H+ + e-



NADPH (Reduced Nicotinamide Adenine

Dinucleotide Phosphate ) NADPH is the reducing power used in light independent phase.

The electron converts low energy compound ADP into high energy compound ATP by adding one inorganic phosphate group PHOTOPHOSPHORYLATION Light Energy

ADP + iP

ATP

PHOTOPHOSPHORYLATION is the production of high energy compound ATP

from low energy compound ADP using inorganic phosphate and light energy. End products of Light dependent phase of photosynthesis – NADPH, ATP, O2 NADPH – Reducing agent of Light independent phase ATP – Energy source for Light independent phase O2 – Utilized the cells for oxidation of glucose and released into the atmosphere as a by product  LIGHT INDEPENDENT PHASE (BIOSYNTHETIC PHASE/ CALVIN CYCLE)

Site – Stroma of the Chloroplast Take place without using light energy. Major event:  CO2 is reduced to Glucose by H+ of

NADPH using

energy from ATP(Fixation of CO2 – Glucose)  Enzyme catalysed reaction.  CO2 enters into a cycle of reaction with the help of a CO2 acceptor

RuBP (Ribulose biphosphate)  NADPH - NADP  ATP - ADP  RuBP - Regenerated after reaction.  End products of Light independent phase of photosynthesis -

GLUCOSE  End products of photosynthesis  Glucose, Oxygen and Water

–

 Fate of the products of photosynthesis  Glucose

– Readily soluble in water

 Utilized the cells for its oxidation to release energy.  Converted to starch for storage.(Conversion of several molecules of

glucose into one molecule of starch – POLYMERISATION)  Convert to sucrose for translocation.  Used to synthesize cellulose, fats and proteins.  ADAPTATIONS IN LEAF FOR PHOTOSYNTHESIS

Large surface area – maximum absorption of light Arrangement of leaves – At right angle to the source of light to obtain maximum light. Cuticle and upper epidermis – Transparent and water proof to allow light to enter freely. Numerous stomata – Rapid exchange of gases Thin leaves – Reduce distance between cells to facilitate rapid transport gases Chloroplast more on upper layer – To obtain light energy quickly Extensive vein system – rapid transport of water, minerals and food Loosely arranged spongy mesophyll – sufficient space for the exchange of gases  FACTORS AFFECTING PHOTOSYNTHESIS

Light intensity CO2 concentration

EXTERNAL

Temperature Water content Chlorophyll INTERNAL Protoplasm Structure of leaf  CARBON CYCLE – Leads to the formation of fossil fuels  CARBON CYCLE involves a series of chemical reactions in which Carbon in

CO2, from the atmosphere used by living organisms and finally returned to the air.



ABSORPTION BY ROOTS – Key points PLANT PHYSIOLOGY is the branch of biology which deals with the study of the life functions of plants.







ROLE OF WATER IN THE LIFE OF PLANTS: 

Water is the major constituent of plant body.



Water constitutes more than 80% of the cell cytoplasm and it is essential for the normal functioning of a cell.



As water is the universal solvent, many substances can dissolve in it.

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It is a medium of transportation of soluble inorganic salts and minerals.

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Plants need water to carry out photosynthesis.

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Plants need water to carry out transpiration.

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Water is essential for proving turgidity (stiffness) to plants – As a means of mechanical support.

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Water is essential for the germination of seeds.

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Water controls the opening and closing of stomata.

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It maintains the body temperature.

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Water is required for the absorption of mineral nutrients.



Water is very much essential for carrying out normal physiological activities of plants.



Soil is the basic source of water to plants.



Roots are the water absorbing organs of terrestrial plants.

The basic Functions of Root: 

Fix the plants in the soil.



Absorb water and minerals from the soil.



Conduction of absorbed water and minerals.





Storage of food.



Helps in vegetative propagation.

How are roots adapted for absorption of water? 

A great surface area provided by rootlets and root hairs.



Higher concentration of cell sap in the root hairs.



Thin walled root hairs.



Root hair is the microscopic root epidermal outgrowth or extension / Root hair is the extension of root epidermis.



The various processes or phenomena which result in the absorption and conduction of water in plants:







Imbibition



Diffusion



Osmosis



Active transport



Turgidity and



Flaccidity

IMBIBITION is the phenomenon by which the living or dead plant cells absorb water by surface attraction. EXAMPLE OF IMBIBITION  Swelling of dry seeds, grains.  Swelling of wooden doors.





DIFFUSION is the free movement of molecules of a substance from the region of their higher concentration to a region of their lower concentration when the two are in contact. EXAMPLE OF IMBIBITION  Spreading of perfume smell.  Dissolving sugar in water.  Coffee grains mix up with milk.

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

 

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OSMOSIS is the movement of water molecules from the region of their higher concentration to the region of their lower concentration across a semi-permeable membrane ACTIVE TRANSPORT is the movement of molecules from the region of their lower concentration to the region of their higher concentration using energy. OSMOTIC PRESSURE is the minimum pressure that must be exerted to prevent the passage of solvent into the solution when the two are separated by a semi permeable membrane. OR OSMOTIC PRESSURE is a measure of the tendency of a solution to take in water by osmosis. OSMOTIC PRESSURE  It is a mechanical pressure and it is exerted by the solute molecule in a solution.  The osmotic pressure is directly proportional to the concentration of the solution.  Greater the concentration of the solute, greater the osmotic pressure.  Osmosis from a region of lower osmotic pressure to a region of high osmotic pressure. Inward diffusion of water through a semi permeable membrane is called ENDOSMOSIS Outward diffusion of water through a semi permeable membrane is called EXOSMOSIS Relative concentration of a solution is called TONICITY. TONICITY determines the direction and extent of the diffusion of water molecule. Isotonic solution is a solution with relatively equal concentration of solute.

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Hypotonic solution is a solution with relatively lower concentration of solute. Hypertonic solution is a solution with relatively higher concentration of solute. A cell is Hypotonic solution – Osmotic pressure high -Cell loses water – Exosmosis - Flaccid A cell is Hypertonic solution – Osmotic pressure low - Cell gains water –

Endosmosis -Turgid A cell is placed in Hypotonic solution – Cell gains water - Endosmosis Turgid A cell is placed in Hypertonic solution – Cell loses water – ExosmosisFlaccid A cell is placed in Isotonic solution – No gain, No lose.



A cell which is fully distended and cannot accommodate any more water due to endosmosis is called TURGID and the condition is called TURGIDITY



The pressure exerted by the cell wall on the cell content is called WALL PRESSURE



The pressure exerted by the cell content on the cell wall is called TURGOR PRESSURE



Shrinkage of cell protoplasm due to the exosmosis is called Flaccid and the condition is called FLACCIDITY



The phenomenon in which the cell protoplasm shrinks and the cell membrane detaches from the cell wall due to the withdrawal of water due to exsomosis when placed in hypertonic solution is called PLASMOSIS



Flaccidity is the reverse of Turgidity.



The recovery or reversal of plasmolysis is called DEPLASMOLYSIS



When a plasmolysed cell is placed in water before it is dead, the protoplasm again swells up and pressing tight against the wall and the cell becomes deplasmolysed.







Plasmolysis is due to the continuous out flow of water where as deplasmolysis is the result of its reentry. Significance of TURGIDITY 

Movement of water from cell to cell.



Provides rigidity to soft tissues of plants.



Helps to localize cell organelles.



Build up root pressure.



Helps in stomatal movements.



Helps in plant movements.



Helps in scattering of seeds.

Significance of PLASMOLYSIS  





Kills weeds by sprinkling salt around their base. Pickling meat and vegetable by adding salt.

Salting meat kills bacteria by plasmolysis. Salting make the solution hypertonic. Bacteria are killed by plasmolysis of their cells. Excessive use of fertilizers without proper irrigation kills crops. Fertilizers make the soil water hypertonic and the root cells of crops loss water by exosmosis and get plasmolysed.

STAGES OF PLASMOLYSIS

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) ChristSchoolRoad,DharmaramCollegeP.O.,Bangalore560029,Ka

rnataka

Class X EXCRETION KEYPOINTS PART - 1 



The process of eliminating the nitrogenous waste from the body is called excretion. Excretory waste products in Humans: MAJOR WASTES

CHEMICAL PROCESS

SOURCE OF PRODUCTION OF WASTES

ELIMINATING ORGAN

MEANS OF ELIMINATION

CO2, water

Respiration

Body tissues

Lungs

Exhaled air

Urea, uric acid

Deamination

Liver

Kidney

Urine

Excess water

Lungs Skin kidney

Exhaled air Sweat Urine

Excess minerals &salts

Skin kidney

Sweat Urine

Large Intestine Kidney

Faeces Urine

Bile pigments (Bilirubin & Biliverdin)

Destruction of RBCs

Liver

Excretory organs in Humans: EXCRETORY ORGANS

MAJOR WASTES

Kidney Urea, uric acid, Excess water, CO , Excess minerals 2 (Primary &salts, Bile pigments excretory organ) Lungs

CO , water 2

Skin

Excess water, Excess minerals &salts(As part of body’s thermoregulation), Urea, uric acid,(Very small amount)

Liver

Toxic substances



Human excretory system mainly consists of:  A pair of kidneys  A pair of ureters  Urinary bladder  urethra

Kidneys

 Primary excretory organ.  Reddish brown in colour.  Bean-shaped organs.  About 10cm long and 6cm wide.  Located below the stomach, one on

either side of the vertebral column in the lower abdomen.  Protected by last two ribs.  The right kidney is positioned lower

than the left kidney because the right kidney is pushed downward by the liver. Kidney – External structure  Kidney shows two main regions: An outer region - Convex  An inner region 

– Concave

The notch present in the middle part of the inner concavity – HILUM



The expanded funnel shaped part inside the kidney from the hilum – RENAL SINUS/PELVIS

 Renal artery, renal vein nerve fibres, ureters etc. enter and leave the kidney

through the hilum. 

The thin sheet of white fibrous tissue which covers the kidney externally – CAPSULE



The structural and functional unit of each kidney – NEPHRONS/ URINIFEROUS TUBULE

Kidney – Internal structure  Outer CORTEX – Dotted appearance  Inner MEDULLA – Striated appearance  CORTEX has dotted appearance because

Nephrons are highly coiled in this region.  MEDULLA has striated appearance

because the nephrons run straight in this region.  A row of finely striped structures

arranged in the medulla – RENAL PYRAMIDS

 The apex of the pyramids – PAPILLA  Papilla projects into renal pelvis.  Pelvis extends downwards and comes

out of the kidney – URETER URETER

 A narrow tube running down from the inner concavity of the kidneys.  It joins with the urinary bladder at the lower part of the abdomen.  Carry urine produced in the kidneys to the urinary bladder

constantly.(FUNCTION)

URINARY BLADDER

 Located in the pelvic region (Lower

abdomen) 

Stores urine temporarily (FUNCTION)

URETHRA

 The opening of the urinary bladder

to the exterior.  A ring of muscles at the opening of

the urinary bladder into the urethra – SPHINCTER MUSCLE  The expulsion of urine from the urinary bladder to the exterior through

the urethra – MICTURITION (URINATION) [Caused due to the relaxation of sphincter muscle and contraction of urinary bladder]

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) Christ SchoolRo ad,Dhar maramColl egeP.O., Bangalor e560029,Kar nataka

Class X EXCRETION KEYPOINTS - 2

 Each kidney contains millions of microscopic filtering units called

Nephrons or Uriniferous tubules or Renal/Kidney tubules – Structural and functional unit of Kidney.  NEPHRONS

Each Nephron is a highly coiled tube like structure. It is blind at one end and open at the other end. It has main two parts:  Malpighian capsule  Renal tubule

 Malpighian / Renal capsule

Lies in the COTREX of the kidney It consists of BOWMAN’S CAPSULE and GLOMEULUS.

 BOWMAN’S CAPSULE

It is cup like structure formed by the invagination of the blind end of the nephron. It forms a double walled structure (Wall – Single cell)  GLOMERULUS

It is a knot of capillaries present in the cup of Bowman’s capsule. It is formed by the capillaries of incoming blood vessel ( Afferent arteriole) and outgoing blood vessel ( Efferent arteriole).  Renal tubule

The coiled tubular part continues from the Malpighian tubule. It has three parts:  Proximal convoluted tubule(PCT)  Loop of Henle  Distal convoluted tubule(DCT)

 PROXIMAL CONVOLUTED TUBULE (PCT)

Closer to Bowman’s capsule. Highly coiled. Lies in the cortex. Internally the cells of this part lined with microvilli structure to increase the surface area for absorption.

 LOOP OF HENLE

Middle part of the renal tubule. Lies in the medulla of the kidney. Consists of a descending limb, Hairpin loop and an ascending limb.  DISTAL CONVOLUTED TUBULE (DCT)

Last part of the renal tubule. Highly coiled. Lies in the cortex of the kidney. Opens into collecting duct.  COLLECTING TUBULE

Found in the medulla of the kidney Receives contents (URINE) from many nephrons. Opens into the pelvis.  BLOOD VESSELS OF KIDNEYS

Dorsal aorta

Renal artery

Afferent arteriole

Glomerulus

Efferent arteriole

Peritubular network (Secondary capillary network)

Venules

Renal vein

 PHYSIOLOGY OF URINE FORMATION

Major toxic waste materials produced – UREA Site of its production – LIVER Process which leads to its formation – DEAMINATION  STEPS OF URINE F ORMATION:

Ultrafilration Selective reabsorption Tubular secretion

 ULTRAFILRATION

Occurs in the Glomerulus of the Bowman’s capsule. The filtration of blood under great pressure. The efferent arteriole is narrower than afferent arteriole. This develops very high pressure in the glomerulus.(The blood proceeding from the efferent arteriole is relatively thick) Due to the high pressure, all that can pass through the capillary wall get filtered out. The filtration of blood in the glomerulus under extraordinary force is called ULTRAFILRATION. The liquid which filters out during ultra filtration is ULTRAFILTRATE / GLOMERULAR FILTRATE.



COMPONENTS OF ULTRAFILRATE

Water Glucose Amino acids Urea Uric acid Inorganic salts Pigments 

SUBSTANCES WHICH ARE RETAINED IN THE CAPILLRIES

Blood proteins Corpuscles(RBC and PATELETS) Fat (Carried forward through efferent arterioles)  Glomerular filtrate is received by BOWMAN’S CAPSULE  The blood proceeding from the efferent arteriole is relatively thick

and PLATELETS), blood proteins because it contains corpuscles RBCs ( and other large molecules.

 SELECTIVE REABSORPTION

The process of absorbing useful substances from glomerular filtrate into the blood in the secondary capillary network.  SUBTANCES WHICH ARE REABSORBED

Most of the Water by Osmosis Glucose Amino acids Inorganic salts of Na+ , K +, Cl - by Diffusion [Takes place in Proximal Convoluted Tubule, Loop of Henle (Water, Na+)]

 TUBULAR SECRETION

The process of secreting harmful substances from the blood in the peritubular network into the glomerular filtrate through the cells of renal tubule.  SUBTANCES WHICH ARE SECRETED

K+, H+, NH3, Uric acid, Hippuric acid, Creatinine, Chemicals like Drugs, antibiotics(Penicillin) by active transport and diffusion) [Takes place in the Distal Convoluted Tubule]  Selective reabsorption and Tubular secretion maintain the components of

blood and the PH (acid-base balance) of the blood 

The filtrate which drains into the collecting duct after Selective reabsorption and Tubular secretion is termed URINE

 Collecting duct

Pelvis

Ureters

Urinary bladder

urethra

 Urine passes into the collecting ducts to the pelvis and through the ureters

into the urinary bladder is due to ureteral peristalsis and gravity.  Urine is expelled from the urinary bladder through the urethra is due to

the relaxation of sphincter muscles located at the opening of the urinary bladder into the urethra. 

The expulsion of urine from the urinary bladder to the exterior through the urethra is called MICTURITION (URINATION). PARTS OF NEPHRON

ACTIVITY

Glomerulus

Ultrafiltration

Bowman’s Capsule

Receives glomerular filtrate

Proximal Convoluted Tubule

Reabsorption of most of the water, Glucose, Amino acids, + + Inorganic salts of Na , K , Cl

Loop of Henle

Reabsorption of water and Na+

Distal Convoluted Tubule

Tubular secretion - K , H , Chemicals like Drugs, antibiotics etc, absorption of small amount of water and ions.

Collecting Duct

Reabsorption of water, Collect and transport left over filtrate(URINE)

+

+

 CONCENTRATION AND REGULATION OF URINE OUTPUT

Controlled by Antidiuretic hormone (ADH). ADH is produced by the posterior lobe of Pituitary gland. High production of urine due to the insufficient secretion of ADH is called DIURESIS

Substances that increase the formation of urine are called DIURETICS (Liquid diet, Tea, Coffee, Al cohol etc.)  In summer – Less production of urine, more concentrated urine (thicker),

urinate fewer times: Most of the water is lost as sweat through perspiration Kidneys reabsorb water from glomerular filtrate making urine more concentrate  In Winter - Frequent urination, Dilute urine:

No sweating Excess water needs to be eliminated  Drinking enough water helps the kidneys to function properly.

More absorption of water – Diluted Urine, more amount of urine Less absorption of water – Concentrated Urine, Less amount of urine  FUNCTIONS OF KIDNEY 

Elimination of nitrogenous waste materials through urine.



Osmoregulation – The process of maintaining the salt-water balance of the body fluid (Blood) by regulating the composition of the blood.

CONSTITUENTS OF URINE (95% Water and 5% solid wastes) ORGANIC

INORGANIC

Urea (2.3)

NaCl (9.0)

Hormones

Uric acid (1.5)

KCl(2.5)

Certain drugs, Antibiotics

Creatinine (2.6)

NH (0.6)

Excess vitamins

3

OTHER SUBSTANCES (2.5)

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) ChristSc hoolRoa d,Dharmar amColleg eP.O.,Ba ngalore5 60029,K arnataka

CLASS - X NERVOUS SYSTEM - KEYPOINTS (1) 

 



Importance of Nervous System: 

Keeps us informed about the surrounding.



Helps to react to the environment.



Helps to think, remember and reason out.



Controls and co-ordinates various body activities.



Regulates the internal environment of the body.

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Controls and co-ordinates voluntary activities.

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Regulates involuntary activities.

The Nervous system consists of BRAIN, SPINAL CORD, SENSE RECEPTORSand NERVES. The basic structural and functional unit of Nervous system is NERVE CELLS / NEURON. NERVE CELLS / NEURON: 

Shows Irritability and Conductivity. (Properties)



Receive stimuli and conduct them in the form of nerve impulses( Function)



It has mainly three parts – Cell body, Dendrites and Axon.

Grade X Nervous System Key Points 1 Prepared by Ms. Anitha Joseph

Page Number: 1



Cell body or Cyton or Perikaryon 

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



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Contains a large, well defined nucleus and cytoplasm. Cytoplasm contains cell organelles but not centrosome (So cannot divide). Cytoplasm is granular – Nissl’s granules (Fragments of Endoplasmic Reticulum with Ribosomes, concerned with protein synthesis).

Dendrites 

The branched cytoplasmic extensions of the cell body.



Branches are short and many.



The finest branches help them to reach the tiniest part of the body.





It is the main part of the neuron.

Receive nerve impulses and carry it to the cell body(Afferent processes) – [Function]

Axon (Nerve Fibre)  

Single, long, unbranched cytoplasmic extension of the cell body. Highly specialized to conduct nerve impulses.



Carry nerve impulses away from the cell body(Efferent processes)

–

[Function]

Grade X Nervous System Key Points 1 Prepared by Ms. Anitha Joseph

Page Number: 2

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It varies in length from few mm (in the brain) to a metre or more (between spinal cord and toes). Axon is surrounded by multilayered insulation sheath called Myelin Sheath/ Medullary Sheath. The cylindrical cell which covers the myelin sheath is called Neurolemma / Schwann Cells– Produce myelin sheath. The gap between the myelin sheath or neurolemma is called Nodes of Ranvier (Impulse jump from one node to another)

Myelin Sheath/ Medullary Sheath– Functions: 

Greatly increase the speed of impulse along the axon.





Preventing the mixing up of impulses with adjacent neurons. The axon ending have bulb like swellings called synaptic lobes.



Synaptic lobes store certain chemicals called Neurotransmitters ACETYLCHOLINE.



The side branches of axon in some neurons are called Collaterals.

Grade X Nervous System Key Points 1 Prepared by Ms. Anitha Joseph

Page Number: 3



The narrow or microscopic gap between the axon ending of one neuron and the dendrites of adjacent neuron is called Synapse or Synaptic cleft.



Synapse is bridged by the neurotransmitter – Acetyl choline produced by the axon endings.



Synaptic cleft / synapse helps to control and receive many information from different parts of the body at different times.



Conduction of nerve impulse: Impulse is a wave of electrical disturbances (irritability) that sweeps over the nerve cell.

Nerve impulses travel along the axon in the form of electrical impulses. Nerve impulses travel across the synaptic cleft in the form of chemical impulses (due to the neurotransmitter – acetylcholine).

Grade X Nervous System Key Points 1 Prepared by Ms. Anitha Joseph

Page Number: 4

Mechanism of generation and conduction of nerve impulse: 

Normally the outer surface of the axon membrane carries positive charge. This state is called polarized state. It is due to more concentration of Na+ ions outside the axon membrane (while K+ ions are more concentrated inside the membrane). + + + + + + + + + + + + + + + + + + + _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

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+ + + + + + + + + + + + + + + + + + + + POLARISED STATE 

On being stimulated, the axon membrane at that spot becomes more permeable to Na+ ions. Hence the interior of the neuron (axon membrane) becomes positively charged while outer surface become negatively charged. This state is called depolarized state and the region is known as excited region. _ +

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DEPOLARISED STATE 



This point of depolarization becomes a stimulus for the next neighbouring area of the membrane, which in turn becomes depolarized. The previous area becomes repolarized due to the active transport of Na+ again to the outside. This balance is maintained by the active transport of ions to reset the membrane known as Sodium pump. +

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REPOLARISED STATE Grade X Nervous System Key Points 1 Prepared by Ms. Anitha Joseph

Page Number: 5



Changed polarity of membrane results in propagation of the nerve impulse along the membrane.



Conduction of nerve impulse is a wave of depolarization followed by repolarization.



TYPES OF NEURONS 1. Sensory neurons (Afferent neurons)

The nerve cells that transmit impulses from the sense organs (Receptors) to brain or spinal cord (CNS) are called Sensory neuron /Afferent neuron. (Have long dendrites, short axon and cell body is centrally located) 2. Motor neurons (Efferent neurons)

The nerve cells that transmit impulses from the brain or spinal cord (CNS) to sense organs (Receptors) are called Motor neuron / Efferent neuron. (Have short dendrites, long axon and cell body is terminal) 3. Association neurons (Intermediate / Relay neurons)

The nerve cells that are located in theneuron brain or and connect Sensory neurons and Motor arespinal calledcord Association neuron / Intermediate / Relay neurons.



The nerve cell dendrites which respond to stimuli and convert them to sensory impulses are called Receptors. Grade X Nervous System Key Points 1 Prepared by Ms. Anitha Joseph

Page Number: 6

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) ChristSc hoolRoa d,Dharmar amColleg eP.O. ,Bangalo re560029, Karnataka

CLASS - X NERVOUS SYSTEM - KEYPOINTS (2)

 NERVE

A bundle of nerve fibres (axon) of neurons enclosed in a tubular sheath is called a nerve. They are white thread like structures emerging from Brain and Spinal cord. The bundle / aggregate of cell bodies of the nerve cell are called Ganglion(S) / Ganglia (P).  KINDS OF NERVE CELL

1. Sensory Nerves

The nerves which contain only sensory fibres, bringing impulses from the sense organs (Receptors) to brain or spinal cord(CNS) are called Sensory nerves. E.g. Optic Nerve 2. Motor Nerves

The nerves which contain only motor fibres, carrying impulses from brain or spinal cord (CNS) to the effector organs (muscles or glands) are called Motor nerves. E.g. A nerve from the brain to the muscles of the eyeball 3. Mixed Nerves

The nerves which contain both sensory and motor nerve fibres are called mixed nerves. E.g. All spinal nerves

SENSORY NERVES

MOTOR NERVES

NERVOUS SYSTEM Key points – 2; Prepared by Ms. Anitha Joseph Page Number: 1

DIVISIONS OF NERVOUS SYSTEM

Nervous System – Includes Central Nervous System and Peripheral Nervous System Central Nervous System (CNS) – Includes Brain and Spinal cord Peripheral Nervous System (PNS) – Includes Somatic Nervous System and Autonomic Nervous System Autonomic Nervous System (ANS) Parasympathetic nervous system

–

Includes Sympathetic and

Somatic Nervous System (SNS) – Includes Cranial nerves and Spinal nerves Three regions of the brain – Fore brain, Mid brain, Hind brain. Fore brain consists of Cerebrum and Diencephalon. Diencephalon consists of Thalamus and Hypothalamus. Hind brain consists of Cerebellum, Pons varolii and Medulla oblongata.

(PNS)

Cranial Nerves

(CNS)

Connection

Spinal nerves

Cerebellum Diencephalon

Cerebrum Pons varolii

Thalamus

Hypothalamus

Medulla oblongata

BRAIN

A protective skeletal structure of brain – Cranium of the skull A protective membraneous covering of brain – Meninges Meninges - Surrounds the Brain (Location) Protects the brain from shocks and jerks (Function). NERVOUS SYSTEM Key points – 2; Prepared by Ms. Anitha Joseph Page Number: 2

Meninges is three membraneous – 

DURA MATER (Outer, tough)



ARCHNOID (Middle, thin and

delicate) 

PIA MATER (Inner, highly

vascular) The space between the membraneous coverings of the brain is filled with a watery fluid called cerebrospinal fluid. Cerebrospinal fluid protects the brain from shocks and jerks by acting as a cushion or shock absorber (Function). Three regions of the brain – Fore brain, Mid brain, Hind brain. Fore brain consists of Cerebrum and Diencephalon



CEREBRUM

The largest portion of the brain. Divided into two cerebral hemisphere – Right and Left

NERVOUS SYSTEM Key points – 2; Prepared by Ms. Anitha Joseph Page Number: 3

The two cerebral hemispheres are connected by a sheet of nerve fibres – Corpus Callosum. Corpus Callosum transfers information from one cerebral hemisphere to another (Function). Outer part of the cerebrum is called Cerebral cortex and inner part of the brain is called Cerebral medulla. Cerebral cortex consists of cell bodies of neurons and shows grayish in colour. Hence the outer cortex forms grey matter. Cerebral medulla consists of nerve fibres (axons) of neurons and shows whitish in colour. Hence the inner medulla forms white matter.

Cerebral cortex is highly convoluted with a lot of ridges or grooves –To increase the surface area to accommodate more neurons. The ridges are called GYRI and the grooves are called SULCI.

NERVOUS SYSTEM Key points – 2; Prepared by Ms. Anitha Joseph Page Number: 4

Cerebrum shows four lobes 

FRONTAL –



PERIETAL –



TEMPORAL

Reasoning, thinking, speech, memory (Intellectual activities) Movement, Sensation like touch, taste, pressure, pain, heat, cold etc.

– Hearing,

Processing language, meaning of words. 

OCCIPITAL

– Vision

Main functions of cerebrum: 

Seat of intelligence, think, reason out, invent, plan, memorise, consciousness, will power etc.



Controls voluntary actions.



Sensations

Past experiences may be recalled cerebrum hypnotized and skillfully questioned. 

Diencephalon consists of Thalamus and Hypothalamus. THALAMUS acts

as a relay centre for sensory impulses going to the

cerebrum. controls body temperature, water balance, sleep and wake up pattern, hunger, thirst, blood pressure etc. and also controls pituitary gland. HYPOTHALAMUS(Major Homeostatic centre),

NERVOUS SYSTEM Key points – 2; Prepared by Ms. Anitha Joseph Page Number: 5

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) ChristSc hoolRoa d,Dharmar amColleg eP.O.,Ba ngalore5 60029,K arnataka

CLASS - X NERVOUS SYSTEM - KEYPOINTS (3)



Hind brain consists of Cerebellum, Pons varolii and Medulla oblongata.

 CEREBELLUM

Cerebellum is located below the cerebrum above medulla oblongata and behind the pons varolii. It has no convolutions, but has numerous furrows. Outer cortex forms grey matter and inner medulla forms white matter. Helps to maintain body balance and posture. Controls and co-ordinates muscular activities of the body. An alcoholic person when drunk generally walks clumsily because cerebellum is influenced by alcohol. Due to the effect of alcohol, cerebellum is unable to co-ordinate muscular movements properly.  MEDULLA OBLONGATA

Medulla oblongata is located at the base of the brain extensions of the pons varolii. It controls the involuntary activities of the internal organs breathing, heartbeat, peristalsis etc. Damage to Medulla oblongata causes sudden death. PONS VAROLII

Pons varolii is located in the centre of the brain below the cerebellum.

NERVOUS SYSTEM Key points – 3; Prepared by Ms. Anitha Joseph Page Number: 1

It carries impulses between the two cerebellar hemisphere and coordinate muscular movements on both sides. Carries impulses from medulla oblongata to forebrain. 

Thalamus / Hypothalamus lies between the cerebrum and midbrain.



STRUCTURE OF THE BRAIN



SPINAL CORD

Spinal cord extends from the medulla to the lumbar region of the vertebral column. Spinal cord is located within the neural canal of the vertebral column. Unlike the brain, the white matter surrounds the grey matter – the grey matter containing the cell bodies of motor neuron and association neuron is inside and the white matter containing axons running longitudinally to and from the brain and even crossing from one side to the other is outside. The grey matter forms an H shaped area. In the centre is a small central canal along the entire length and contains cerebrospinal fluid.

NERVOUS SYSTEM Key points – 3; Prepared by Ms. Anitha Joseph Page Number: 2

Meninges continue over the spinal cord from the brain and protect the spinal cord from the mechanical shocks and jerks. Hollow cavity at the centre of the spinal cord which is filled with cerebrospinal fluid is called central canal. Function

Conduct sensory impulses from the skin and muscles to the brain. Conduct motor responses from the brain to muscles of the trunk and limbs. Controls reflexes (involuntary) below the neck.

Spinal nerve srcinates from the spinal cord by means of two roots —a dorsal root & a ventral root. Every spinal nerve is mixed nerve having both sensory and motor nerve fibre (axon). The sensory nerve fibres take up the dorsal root. The motor nerve fibre takes up the ventral root. In the grey matter, the dorsal and ventral roots enter and relay/inter neuron connects the sensory nerve and motor nerve. The dorsal root has dorsal root ganglion which contains the cell bodies (cyton) of sensory neurons only. The grey matter of spinal cord contains the cell bodies of relay neurons and motor neurons. PERIPHERAL NERVOUS SYSTEM (PNS)

All the nerves which connect the various parts of the body with CNS.

Cranial nerves Spinal nerves

NERVOUS SYSTEM Key points – 3; Prepared by Ms. Anitha Joseph Page Number: 3

CARNIAL NERVES

SPINAL NERVES

Originating from Spinal cord brain 12 pairs in number 31 pairs Sensory, motor or Only mixed type mixed types

AUTOMATIC NERVOUS SYSTEM (ANS)

Consists of a pair of chains of nerves and Ganglia on either side of the backbone. Consist of a group of nerves, working along with Medulla Oblongata - Nerves connected with internal organ.

Sympathetic Parasympathetic

SYMPATHETIC

PARASYMPATHETIC

Stimulatory in function

Inhibitory in function

Accelerates body activities

Restore body activities

Nerves between neck and Nerves above neck and below waist sacrum ANS carrying out the orders of Medulla oblongata and assisting in controlling the involuntary activities of internal organs. Sympathetic nervous system (ANS) is stimulated by the hormone Adrenalin secreted by adrenal gland. Sympathetic nervous system prepares the body for violent actions during emergency by speeds up the activities of the internal organs. NERVOUS SYSTEM Key points – 3; Prepared by Ms. Anitha Joseph Page Number: 4

Parasympathetic nervous system helps in re establishing the normal conditions by slow down the activities (giving a break). The balance between the Sympathetic nervous system and Parasympathetic nervous system maintaining the normal involuntary action of internal organs. ANS is strongly under the influence of emotions like anger, fear, grief etc The effect of the two parts of ANS on various organs. SYMPATHETIC N S

PARASYMPATHETIC N S

Heart

Heart beat accelerates

Retards

Blood vessel (except coronary)

Dilated

Constricted

Urinary bladder

Sphincter relaxed muscle contract

Sphincter contract muscled relaxed

Pupil of eye

Dilation

Constriction

Sal. glands

Inhibits secretion

Stimulate secretion

Lacrimal glands

Stimulate secretion

Inhibits secretion

Body (as a whole)

Ready for action

Relaxation

Intestine

Decreased peristalsis

Increased peristalsis

Lungs

Dilates

Constricts

ACTIONS

Involuntary Actions Voluntary Actions REFLEXES (Involuntary actions)

An inborn, rapid, automatic response to a given stimulus without involvement of brain. Two types

Simple reflexes/Unconditioned/Natural Conditioned reflexes/Acquired Simple reflexes/Unconditioned/Natural

Inborn reflex with no previous experience or learning Inherited from parents NERVOUS SYSTEM Key points – 3; Prepared by Ms. Anitha Joseph Page Number: 5

Protective and provide functional efficiency Simple reflexes involves two or three neurons only ie., Sensory Neuron, Motor Neuron and Relay Neuron. The nervous pathway of simple reflex is Reflex arc. Reflex arc is the shortest route that can be taken by an impulse

from a receptor to an effector. Examples: Blinking, Coughing, Sneezing, Salivation (while chewing food), Swallowing, Peristalsis, Knee-jerk, Withdrawal of hand when suddenly pricked, Sudden closure of eyelids on exposed to strong beam of light. Reflex arc: Stimulus Receptor (sense organ) neuron (spinal cord) Motor neuron

Sensory neuron Association Effector Response

is a muscle or gland that produces a response or reaction to motor nerve impulse. Effector

Response is a change or a reaction to a stimulus. Conditioned reflex/Acquired reflex 

Acquired during life time due to experience or learning.



Conditioned reflexes are not inborn and are not inherited or cannot be inherited.

Examples: Salivation on sight of food(smell), stand up when teacher comes to class, tie shoe lace without seeing, playing musical instrument, applying breaks while driving, using key of a computer keyboard etc.. NERVOUS SYSTEM Key points – 3; Prepared by Ms. Anitha Joseph Page Number: 6

All reflexes are involuntary, but all involuntary actions are not reflexes. Certain voluntary actions become involuntary by consciously repeating them with specific stimuli and such actions are called conditioned reflexes.

NATURAL REFLEXES

ACQUIRED REFLEXES

Inborn

Acquired during life time

Inheritable

Cannot be inherited

No previous experience required

Developed by experience or learning

Directly related to stimulus Similar in all humans / Similar among all individuals of any one species. Voluntary action

Brought about by a condition totally different from direct initial stimulus Differs in different individuals – subject to learning experience Involuntary action

Initiated by willing thought

Initiated by stimulus

Fulfill a desired goal

Self protective

Commands srcinate in brain Involves only muscles

In spinal cord and ANS Involves muscles and gland

NERVOUS SYSTEM Key points – 3; Prepared by Ms. Anitha Joseph Page Number: 7

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) Chris tSchoolR oad,Dhar maramColl egeP.O., Bangalore 560029,Kar nataka

GRADE X SENSE ORGANS - EYE Key points  Location – In front of the head, in the orbits or sockets in the skull.  Function - Provide the sense of vision.  Eye ball is connected to the orbits by muscles. Muscles help the eye ball to

move up and down and sides

 Accessory Structures – For protection.

Eyelid – Protect the eye from dust particles, excessive light, helps to spread tears over eyeball. Eyelashes – Protect the eye by preventing larger particles fall into the eyes. Eyebrows – Protect the eye from raindrops or sweat trickling into it. Lacrimal glands (Tear glands) Location – Upper, outer end of the eye ball beneath the eyelid. Function – Produce tears.  Functions of Tear  Washes out dust particles (Clean the eye).  Moistens and lubricates the eye.  Contains

enzyme lysozyme (antibacterial) protects the eye by destroying bacteria.

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 1

which

STRUCTURE OF EYE  3 Distinct layers

Outer – Fibrous sclerotic (sclera) Middle – Vascular choroid Inner – Nervous retina  SCLERA

Completed layer of eye Forms the white part Thick, white, tough, fibrous, non elastic, opaque (expect the front …) Functions  Gives shape to the eye ball  Protects the inner parts of the eye

Cornea – The part of Sclera which is transparent and slightly bulged out in front of the eye. Conjunctiva – The entire front part of the eye (only) is covered by a thin transparent membrane which continues with the eyelids (not a

part of eyeball)  Functions – Protect the eye in front part.

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 2

 CHOROID

Incomplete layer Dark brown, highly supplied with blood vessels Pigment melanin present A part of it can be seen through transparent cornea. (iris) Functions –  Preventing reflection and scattering of light inside the eye by absorbing them.  Also nourishes the cells of retina

Iris  A circular disc of choroid which can be seen through the

transparent cornea, with an opening at the centre.  Eye colour refers to the colour of iris  Functions – Helps to control the size of the pupil.

Pupil –  The circular opening at the center of iris  Function – Helps to regulate the amount of light enter into the eye

Iris has two sets to muscles which are antagonistic to each other in their function - Radial muscle and Circular muscle.

Dim light

Bright light

Radial muscle

Contracts (R C)

Relax (R R)

Circular muscle

Relax( C R)

Contract( C C)

Dilates

Constricts

Pupil

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 3

The adjustment of the size of pupil regulates the amount of light entering the eye. Difficulty in viewing objects while moving:  From bright light – dim light

-- Dark adaptation

 From dim light – bright light

-- Light adaptation

Reasons of Dark adaptation. (From bright light – dim light) 

Regeneration of visual purple(rhodopsin)

 Dilation of pupil, allowing more light to enter the eyes.

Reasons of Light adaptation. (From dim light – bright light)  Degeneration of visual purple(rhodopsin)  Constriction of pupil, reduce the amount of light entering the eyes.

Ciliary body – The expanded portion of choroid at the junction of choroid and iris, which is very thick. EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 4

Ciliary body has ciliary muscles, which on contraction and relaxation change the shape of the lens. Suspensory ligaments – Fibers arising from the ciliary body, holding the eye lens in its position. Eye lens – Transparent elastic biconvex crystalline body located just behind the pupil, held by suspensory ligaments from both sides.

Power of accommodation – Ability of the eye to view objects at different distances by changing the curvature of the eye lens. Ciliary muscles, which on contraction and relaxation helps to change the curvature of eye lens. Focal length is changed by making the lens thinner or thicker. Focal length – The distance at which something in focus/ The distance of focus from optic centre of the lens. Accommodation apparatus which includes Ciliary muscles, suspensory ligaments, elasticity of eye lens

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 5

Distant Object (Normal view)

Near Object (Closer)

Ciliary muscles

Relaxed

Contract

Susp.ligaments

Pulled tight

Slacken or loosen (Tension relaxed)

Eye lens

Less convex (long, thin)

More convex (thick, short)

 RETINA

Incomplete layer Most sensitive layer Contains photosensitive receptor cells – Rods, Cones. Function – Provide surface for image formation Rods

Cones

Pigment

Rhodopsin(visual purple)

Iodopsin

Location

At the periphery of retina (mostly)

In the centre of the retina (mostly)

Sensitive

To dim light

To bright light

Vision

Black and white

Colour

Types

Only one type

3 types

Regeneration

Rapid

Slow

Yellow spot/ Forea centralis/ Macula lutea  Lie almost at the centre on the horizontal axis of the eyeball.  Contain maximum number of cone cells.  Region of best/brightest vision of normal eye. (also colour vision)

We move our eyes from word to word as we read a line through a printed page. This is because the best vision is possible on the yellow spot. EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 6

Blind spot  Lateral to the yellow spot on the nasal side.  Contain no sensory cells.  The optic nerve leaves the eye ball at this point. (The nerve fibres

from all the photo sensitive cells of the retina converge and bundle together to form optic nerve)

Chambers of the eye  Anterior chamber – Aqueous chamber  Posterior chamber – Vitreous chamber

Aqueous chamber small Anterior –

Vitreous chamber Posterior

Between cornea and lens Filled with clear aqueous humour

watery

– large Behind the lens

fluid

Functions Keeps the lens moist

Protects lens from physical shocks

– Filled with jelly like thick fluid – vitreous humour

Helps in maintaining the shape of eye ball Protects retina and its nerve endings

Refracts light

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 7

 WORKING OF EYE

Object (light trays) Conjuctiva  Cornea  aqueous humour  Pupil  Lens  Vitreous humour  Yellow spot of retina Optic nerve Occipital lobe (cerebrum) Structure of eye which converge the light rays Cornea, Aqueous humour, Lens Site of image formation Yellow spot of retina Image formed on the yellow spot Real, inverted and small Visual centre of brain Occipital lobe of cerebrum Stereoscopic vision / Binocular vision

Stereoscopic vision is a three dimensional effect of the image in which man can perceive relative distance or depth of the object. This is due to the simultaneous focusing of an object in both the eyes from different angles. (The two images which are formed get overlapped in the brain and give a 3D effect) Advantages of having two eyes: Gets 3D effect of the object can be perceived i.e., able to perceive depth, height and relative distance of the object  Donation of eye – cornea of eye  Visual centres of cerebrum is affected by alcohol – Double vision

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 8

Common eye defects

(Diagrams – REFER TEXT BOOK) Defect

Cause

1. Myopia (short sightedness) (Diffculty to view

Correction

Concave lens Eyeball lengthened from (Diverging lens) front – back

far ojects)

Lens is too curved (short, thick) Images of distant objects form in front of the retina 2. Hyeropia (long sightedness) (difficulty to view near objects)

Shortening of eyeball from front – back Lens becomes too flat (thin, long)

Convex lens (Converging lens)

Images from near objects falls behind the retina 3. Astigmatism (Some parts of the

Uneven curvature of cornea

objects are seen in focus while others are blurred) 4. Presbyopia (in old age) -- Diffculty in viewing near objects. (A kind of long sightedness 5. Cataract (Partial or Total Blindness)

(eyelens)

Cylindrical lens

Lens loses it flexibility

Convex lens

Lens turn opaque

Surgical removal of eye lens and using spectacles which is highly convex lens

6. Night blindness (difficulty in viewing dim light)

Non formation of Supplement of Vit A food in diet visual purple of the rod due to the deficiency Vit A in the diet Vit A is essential for the production of rhodopsin pigment which are essential for viewing objects in dim light

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 9

7. Colour blindness (cannot discriminate between certain colours such as red and green) 8. Glaucoma – Sees flashes of light and coloured rings around the object

Due to the presence of a defective recessive allele on the ‘X’ chrom Due to increased intra occular

Drain excess fluid by operation and restore

pressure hardeningand of eye ball

normal pressureintra occular

EYE KEYPOINTS PREPARED BY ANITHA JOSEPH; PAGE No. 10

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) ChristSchoolRoad,DharmaramCollegeP.O.,Bangalore560029,Karnataka

ENDOCRINE SYSTEM - Keypoints  Endocrine glands  Exocrine

are duct less gland which secrete hormones. glands are ducted glands which produce various secretions like saliva,

tear tc.  

Purely endocrine glands are called Holocrine which produce hormones only. Partly endocrine and partly exocrine are called Heterocrine.



Hormones – characteristics:

Chemical messengers Secreted by endocrine glands directly into the blood (by endocrine gland) and transported by it Produced in small quantity Specific in their function Protein, peptide , steroid in nature Secreted in response to specific stimuli Acts on particular target organ Helps to maintain Homeostasis Hormonal control

Nervous control

Work slowly

Fast, Quick

Transmitted chemically

Electrically, chemically

Conducted through blood

Nerves

Target organ can be any body parts

Specific muscles and glands

Short term or long term effect(mostly)

Short term

Affect growth

Does not affect growth

Cannot be modified

Can be modified by learning experience

Regulate metabolism

Cannot regulate metabolism

Can bring about specific chemical Does not influence chemical changes changes

ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 1

ADRENAL GLAND 

Also called super gland as they are placed on the top of each kidney.



Structure – Two small cream coloured cap like structure



Location – On top of each kidney



Adrenal gland consists of two parts: Adrenal cortex Adrenal medulla



Hormones of adrenal cortex

Gluco corticoids Mineralo corticoids Sex corticoids Gluco corticoids Eg: Corticosterone Functions Regulates metabolism of carbohydrates, fats, proteins. Control salt water balance of the body. Mineralo corticoids Eg: Aldosterone Functions Regulate mineral metabolism. Control Na and K ratio in the body. + (Increase reaborsption of Na in the renal tubules) Sex corticoids Eg: Androgen Functions Stimulate the development of sexual characters in male and female.

ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 2



Effect of hypo secretion of adrenal cortex hormones

Addison’s disease Symptoms Hypoglycemia (low blood sugar) High concentration of K

+

Pigmentation of skin 

Effect of hyper secretion of adrenal cortex hormones

Cushing’s syndrome Symptoms Hyperglycemia Moonshaped face Hypertension, obesity THYROID GLAND 

Structure : Brownish red butterfly shaped, bilobed gland



Location : Infront of the neck, below the larynx



Hormones of Thyroid gland Thyroxine Calcitonin



Functions (An Iron containing hormone) Regulate the basal metabolic rate Control oxidation of glucose and energy production in cells and tissues Helps to maintain the body temperature

(Helps to regulate the general growth and development of the body by controlling the metabolic activities and oxidation process in cells and tissues) 

Hypo secretion of thyroxine Cretinism (Infancy) Myxoedema(Adulthood) Simple goiter (Iron deficiency) ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 3

Cretinism

Due to thyroxine deficiency in infancy(improper functioning of thyroid gland) Symptoms Stunt physical growth(short stature of miniature forms) Mental retardation Pot belly, pigeon chest General weakness and low resistance Myxoedema(Gull’s disease)

Due to throxine deficiency in adults Symptoms Swollen face and hands(oedema) (Oedema is the thickness or swelling of skin due to the accumulation of fluid in the subcutaneous tissue) Physical and mental dullness Sluggishness and laziness Low body temperature and slow heart beat Simple Goitre

Due to the lack of Iron in the diet leads to enlargement to thyroid gland—Hypertrophy (Inorder to absorb more I2) Symptoms Enlargement of thyroid gland as a swelling in the neck region Rectification Addition of iodized salt in the diet Simple goiter is commonly observed in people live in hilly areas and is seldom observed in people live in coastal areas. Why? In hilly areas most of iodine in soil is washed away by running water. So water and food produced in this area are devoid of iodine – leading to goiter (endemic disease) In coastal region people depend largely of seafoods which are rich in iodine. So seldom occur ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 4



Hyper thyroidism – Exophthalmic goiter (Grave’s disease) Due to hyperactivity of thyroid gland Symptoms Protruded eyes Increased metabolic rate, increased heart beat, increased breathing rate Nervousness, irritability

Rectification Surgical removal of a part of thyroid gland PANCREAS -- Heterocrine gland (Partly endocrine, Partly exocrine) 

Structure Flattened triangular shaped structure





Location Just below (posterior) to the stomach attached to the duodenal loop in the abdominal cavity. Endocrine part Islet of langerhans—produces hormones.



Exocrine part Accini—produce digestive juice.



Hormones of Pancreas cells(Alpha) –Glucagon cells(Beta)—Insulin cells(Delta)—Somatostanin

INSULIN—Antidiabetic hormone

Helps to lower the blood glucose level: by promoting body cells to increase glucose oxidation by initiating the conversion of glucose—glycogen and store in liver cells and muscle cells GLUCAGON

Helps to raise the blood glucose level by stimulating the breaking down of glycogen to glucose ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 5

Insulin and Glucagon – helps to maintain the blood glucose level 

Hypo secretion of Insulin – DIABETES MELLITUS Symptoms Hyperglycemia (high conc.of blood glucose) Urine is loaded with glucose Loss of weight and weakness(Fatigueness) Thirst Frequent urge of urination Failure of conversion of glucose – glycogen

Body cells cannot utilize glucose though the glucose level in the blood is very high because hypo secretion of insulin retards glucose oxidation in tissues and conversion glucose to glycogen. So glucose gets concentrated in blood (Hyperglycemia) and goes waste along with urine. Remedy Cut down carbohydrate rich food in the diet Regular injection of insulin

Overdose of insulin to a diabetic patient leads to insulin shock (Unconciousness) due to sudden fall of glucose than the required level. A bite of candy/sweet biscuit or drinking sugar solution is advisable. 

Hypersecretion of insulin – State of unconsciousness/Coma Symptoms Hypoglycemia (drastic lowering) Slip into a state of unconsciousness and into coma

Too less glucose in the blood fails to supply sufficient glucose to brain cells for their energy production. (Brain cells need continuous supply of oxygen and glucose)

ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 6

PITUITARY GLAND—THE MASTER GLAND  

Secretions of pituitary gland control and regulate the secretions of other endocrine gland Structure Pea shaped







Small structure Location Base of the brain attached to hypothalamus Forms a link between Nervous System and Endocrine System. Consists of three lobes: Anterior lobe Intermediate lobe Posterior lobe



Hormones of anterior lobe of Pituitary 1. Growth Hormone (Somato tropic hormone)

Stimulate the growth of bones and muscles (soft tissues of the body) Hypo secretion of Growth Hormone Dwarfism—Under secretion in early age of life Short stature of body (Body is fully developed but retains the size of a child)

Hyper secretion of Growth Hormone Gigantism—Over secretion in childhood Abnormal height with long bones (Height is not proportionate to the age group)

Acromegaly—Over secretion in adolescence or adulthood Disproportionate growth of bones and body gets a giant structure

2. Thyroid stimulating Hormone TSH Stimulate thyroid gland to secrete thyroxine

ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 7

3. Adreno cortico tropic Hormone ACTH

Promotes and maintains the growth and development of adrenal cortex and stimulate it to stimulate its hormones. 4. Follicle stimulating Hormone FSH

Stimulate the development of seminiferous tubule and helps in the production of sperms. Stimulate the development of ovarian follicle and help in the production of ovum. 5. Luteinizing Hormone LH

Stimulate ovulation Helps in the formation of corpus luteum Stimulate corpus luteum to secrete progesteron 6. Interstitial cell stimulating Hormone ICSH Stimulate the development of interstitial cells and its secretion i.e., testosterone 7. Luteotropic Hormone or Prolactin Enlargement of breasts during pregnancy Controls secretion of milk after delivery

FSH, LH, ICSH—Gonadotropic Hormones - Control gonads and their secretion. Except growth hormones all other Hormones by anterior pituitary are Tropic Hormones - Hormones which control the secretion of other endocrine glands 

Hormones of posterior pituitary 1. Antidiuretic Hormones or Vasopressin(Water retaining Hormone)

Promotes reabsorption of water by the kidney tubules(collecting ducts of nephrons) Helps the body to maintain water balance and controls the secretion of urine.

ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 8

Hyposecretion of ADH Diabetes insipidus Frequent copious urination(A great amount of water is lost as urine) No glucose is lost in the urine(dil.urine) Severe dehydration (may lead to even death) 2. Oxytocin –(Birth Hormone) Causes contraction of uterus during child birth Ejection (secretion) of milk during lactation FEED BACK MECHANISM Hormones work on the principle of Feedback mechanism—Secretion of a hormone is inhibited or stimulated by the end product of its activity. If stimulated positive feed back If inhibited negative feed back EXAMPLE ↑Blood glucosestimulate βcellsinsulin↑glucose↓ cells inhibit production –ve  insulin↓falling glucose

cell stimulate +veglycogen↑

Feed back control mechanism enables to maintain homeostasis by hormones. Their secretions are to be regulated in co-ordinated manner so that the right hormome is secreted at the right time in the right quantity. Adrenalin by Adrenal medulla(link between N.S & E.S) - (Epinephrin)

Adrenalin cts on organs supplied by sympathetic nerve fibre of autonomic nervous system. It is produced when the body is in stress like anger, fear, grief etc. It helps the body to face physical stress like muscular exertions, emotional stress etc … So it is called emergency hormone.

The various effects of adrenalin on internal organs (increased heart beat, increased blood supply to muscles, release more glucose to blood, increased blood pressure, increased breathing rate etc…) allow the body to operate with extra speed, awareness and efficiency. ENDOCRINE SYSTEM – Keypoints Prepared by Ms.Anitha Joseph pg. 9

CHRIST SCHOOL (Affiliated to the Council for the ICSE, New Delhi. Reg. No: KA260/2013) Chris tSchoolR oad,Dhar maramColl egeP.O., Bangalore 560029,Kar nataka

REPRODUCTION - KEYPOINTS

1. REPRODUCTION is

2.

the process of producing young ones of its own kind by

an organism. Significance of reproduction: Helps in the continuity of species Helps in the existence of life on earth Asexual reproduction Offspring produced from a single parent Gametes are not formed (no fusion of gametes) Offsprings will be exactly like the parent

3.

Sexual reproduction Offspring produced from two parents, male and female Gametes are formed (fusion of gametes) Offsprings show difference

Puberty —The age at which the reproductive system begins to function.

Boys—between 13-17yrs Girls—between 11-16yrs 4.

Secondary sexual characters—The outwardly differentiation features shown by males and females called secondary sexual characters  Male

Growing hair on face (beard, moustache), armpits, chest, pubic region etc… Broadening of shoulders Deepening of voice with the enlargement of larynx Body become muscular Penis, scrotum enlarges  Female

Growing hair in armpit and pubic Widening of hips (Pelvic region broadens) Enlargement of breasts Menstruation begins Reproductive structure enlarges REPRODUCTION Key points Prepared by Ms.Anitha Joseph 1

5. SEXUAL REPRODUCTION IN HUMANS: 

The organs of the human reproductive system are divided into two:The primary reproductive parts(Include the gonads which produce the gametes). The accessory reproductive parts(all those structures which help in the transfer and meeting of gametes leading to the fertilization and growth and development of the zygote).

6.

Male Reproductive System:  The male reproductive system consists of:

A pair of Testes(p) A duct system Accessory glands A penis Urethra

 Testes (Testicles) — Primary sex organ.

Function Produce sperms Produce sex hormone testosterone Location Outside the abdomen in the scrotal sacs just behind the penis(extra abdominal)

Why extra abdominal? To keep the testes at a temperature 2-3 0C lower than the body temperature, because the production and maturation of sperms is feasible at lower temperature than normal body temperature.  Testes are descended into scrotal sacs through inguinal canal just before

birth Inguinal canal

Helps the testes to descend into scrotum just before birth Passage of nerves, blood vessels, vas deferens etc…  The process of formation of sperms from germ cells is called

spermatogenesis. REPRODUCTION Key points Prepared by Ms.Anitha Joseph 2

 Seminiferous tubules (sperm producing structure)

Location—Testis Function—Produce sperm  Leydigcells or Intestitial cells or Tunical albugenia —The packaging tissue

(connective tissue) present between coils of seminiferous tubules. Location—Between the coils of seminiferous tubules in testis Function—Produce testosterone

Pathway of sperm

Seminiferous tubules E fferent ducts (vasa efferentia) deferens (vasa deferentia / sperm duct) Urethra

E pididymis

Vas

 Epididymis -- A tubular knot on the upper posterior of the testis.

Function—Storage and maturation of sperms.  Vas deferens – Partially coiled tube ascended into abdomen through

inguinal canal from the testes. Function—Carry sperms from testes to urethra. Accessory glands (Male)  Seminal vesicle

Location – Between the posterior surface of urinary bladder and rectum Function—Secrets alkaline fluid which acts as a medium for the transportation of sperms

REPRODUCTION Key points Prepared by Ms.Anitha Joseph 3

 Prostate gland

Location — Surrounds the urethra close to its srcin from the urinary bladder. Function — Secretes an alkaline fluid which increases the mobility and viability of Sperms.  Cowpers gland Location—opens into urethra just before it enters into the penis. Function—Secrets a lubricating fluid and lubricates penis during copulation. Semen

An alkaline milky fluid which contains secretions of seminal vesicles, prostate gland, cowpers gland and a large number of sperms.  Penis

Function Copulatory organ of male, serves as a passage for both semen and urine. Helps to transfer sperms into the female genitalia during copulation Location—In front of the testicles Duct system A pair of epididymis A pair of vas deferns A pair of ejaculatory ducts (from seminal vesicles) Urethra 7.

Female reproductive System  The female reproductive system consists of :

A pair of Ovaries A pair of oviducts Uterus Vagina and Vulva

REPRODUCTION Key points Prepared by Ms.Anitha Joseph 4

 Ovary

Location — On the lower part of abdominal cavity one on each side of body attached to uterus. Function Produce ovum Produce female sex hormone Oestrogen, Progesterone  The process of production of ovum from

the germ cells is called Oogenesis  The fluid filled cellular sac in which egg

cell (ovum) mature is called

Graafion

follicle  The process of releasing mature ovum

by the rupturing of graafion follicle is called ovulation  An

yellow mass formed from the remnant of graafion follicle after ovulation is called corpus luteum

 Corpuslutem — produce progesterone

(progesterone — pregnancy supporting hormone)

Pathway of ovum

Ovary(graafianfollicle) Vagina Vulva

F imbriae

Ostium

Oviduct

REPRODUCTION Key points Prepared by Ms.Anitha Joseph 5

Uterus

 Fallopian tube (oviduct)

Function - Site of fertilization Movement of ovum — Peristaltic movement of the muscular wall of oviduct By the lashing of cilia, located in the inner wall of oviduct.  Uterus

Location - In the lower abdomen (pelvic cavity) between the urinary bladder and rectum. Function - Harbor, protect and nourish the growing embryo.  The lower narrow neck region of uterus – cervix  The internal mucus membrane lining of uterus – Endometrium  Vagina

Receives semen (sperms) during copulation. Acts as a passage for menstruation (uterine secretion). Birth canal(passage for child birth).  Vulva

External female genital organ. Receives openings from vagina & urethra. Has two folds skin on side (labia majora, labia minora).

Parts of female reproductive system homologue of male reproductive system Testes Vas deferens Scrotum Penis

— Ovaries — Fallopian tube — Labia majora — Clitoris

Clitoris is a small rod like structure located in front of urethral opening.

REPRODUCTION Key points Prepared by Ms.Anitha Joseph 6

 The onset of puberty in female is marked by menstruation  Menstruation is the discharge of blood due to the rupturing of endometrium

along with unfertilized egg and ruptured tissue through the vagina  Commencement of menstruation is called Menarche  Stoppage of menstruation is called Menopause  Reproduction life of female (around)32years  Approximate no.of eggs reach maturity—416 eggs  The recurrence of ovarian cycle about 28 days in the reproductive life of a

female is called menstrual cycle

I.

Menstrual phase (3—5 days)

Uterus — Discharge of blood due to rupturing of endometrium. Ovary — Degeneration of corpus luteum. Formation of new ovum in the follicle. II.

Follicular phase(5—12days)

Uterus — Regeneration of uterine wall with thickening of blood vessels. Ovary—Maturation of ovum in the graafian follicle. oestregen FSH REPRODUCTION Key points Prepared by Ms.Anitha Joseph 7

III.

th

th

Ovulatory phase (13 or 14 day)

At the midst of menstrual cycle oestregen, lutenizing H Uterus—Thickening of endometrium with blood vessels Ovary—Ovalution LH IV.

Luteal phase(15-28 days)

Uterus—Uterine wall keeps thickening Ovary—Formation of corpus luteum LH

H ormones involved FSH

 Spermatogenesis (seminiferous tubule)  Oogenesis (graafian follicle)

LH

Ovulation Maintenance of corpus luteum

Secretion of progesterone CSH Secretion of testosterone 8.

FERTILIZATION  Process of fusion of nuclei of male and female gametes(sperm, ovum)  Sperm (motile)

Acrosome Location -- at the top of head of human sperm Function — Produce enzyme sperm lysine (hyaluronidase) which facilitate the entry of sperm into the egg by dissolving the cell membrane of egg Nucleus – Haploid – 23 chrom. – 22 atuosome + X or Y Middle piece Mitochondria—provide energy for the activity of sperm to swim Tail Helps in lashing movement for propulsion REPRODUCTION Key points Prepared by Ms.Anitha Joseph 8

 A chemical barrier prevents the entry of more than one sperm nucleus

into the egg. 

F ertilization Restore the chromosome number to diploid Helps to fertilize the egg

 Fertilized egg—Zygote  The repeated mitotic division of zygote — Cleavage  The mass of cells (ball) formed by the cleavage of zygote — Blastocyst  The process of attachment of blastocyst(fertilized egg) to the uterine wall

is Implantation (a week after the fertilization)  Implantation produces the state of Pregnancy 

Zygote Morula Blastula(Blastocyst)

 The outer most layer of blastocyst —Trophoblast  Trophoblast develops into two membranes.

Amnion (inner) Chorion (outer)  Extra embryonic membrane

Chorion, amnion, allantois, yolk sac Chorion—helps in the formation of placenta Amion—protective membrane cover Allantois &yolksac—provide nourishment and stores waste materials. REPRODUCTION Key points Prepared by Ms.Anitha Joseph 9

 Placenta

An intimate connection established between the mother and the foetus by the interlocking of chorionic villi and uterine villi Functions—Placenta acts as: Nutritive organ—supply nutrients Respiratory organ—exchange of respiratory gases Excretory organ—removes waste material like urea Endocrine gland—produce oestrogen, progesterone Protective—prevent the passage of germs

Why Placenta?

The high blood pressure of mother ’s blood may seriously damage the soft and delicate tissues of the foetus, so direct blood supply, only through placenta.  Placenta is permeable to nutrients, respiratory gases, antibodies, urea,

certain viruses like HIV  The placenta is connected to the foetus by a cluster of blood vessels —

Umbilical cord.  Umbilical cord – blood vessels —Umbilical artery, Umbilical vein  Umbilical artery—Deoxygenated blood, urea from foetus to placenta  Umbilical vein—Oxygenated blood, nutrients from placenta —foetus  The blood of foetus and mother never mixes up.  Exchange of matters take place at placenta by diffusion.

REPRODUCTION Key points Prepared by Ms.Anitha Joseph 10

Amnion Protects the embryo Produce amniotic fluid Function of amniotic fluid Acts as a shock absorber and protect the embryo from mechanical shock and jerks Keeps an even pressure all around the embryo Allows the foetus some restricted movements Prevents the sticking of the foetus to the amnion  Gestation—The full term of the development of an embryo in the uterus  Gestation period 280 days  Parturition—The expulsion of fully developed foetus from the uterus

through the vagina is parturition.  Hormone—Oxytocin  After birth—The placenta which comes out after parturition

If fertilization does not occur Corpus luteum degenerate Progesterone stops producing Disintegration of the uterine wall(Degeneration) Menstruation occurs If fertilization occur Corpus luteum persists Progesterone continues to thicken Uterine wall continue to thicken Menstrual cycle stops temporarily 9.

Twins

Identical (monozygotic) Produced from one fertilized egg Both are of same sex Identical to each other

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Fraternal (Dizygotic) Produced from two different fertilized egg Either a boy and a girl or both boys or both girls Non identical 10.

Important definitions:

Reproduction—The process of producing young ones of its own kind by an

organism Puberty—The period during which the reproductive system begins to function/The age at which the boy and girls attain sexual maturity Spermatogenesis—The process of formation of spermatozoa (sperm) from germ cells Oogenesis—The process of formation of ovum from germ cells Ovulation—The process of releasing mature ovum by the rupturing of graffian follicle is ovulation Menarche—Commencement of menstruation Menopause—stoppage of menstruation Fertilization—Process of fusion of the nuclei of male and female gametes Implantation—The process of attachment of blastocyst(embryo) to the uterine wall Placenta—is an intimate connection established between the mother and the foetus by uterine villi and chorionic villi Gestation—The full term of the development of an embryo in the uterus Parturition—The expulsion of fully developed foetus out of the uterus due to powerful contraction Contraception—Methods to prevent pregnancy Vasectomy—Surgical method of contraception in male by cutting and ligating sperm duet REPRODUCTION Key points Prepared by Ms.Anitha Joseph 12

Tubectomy—surgical method of contraception in female by cutting and ligating fallopian tube Demography—Statistical study of human population Population density—The number of individuals per square kilometer at any given time Natality—The number of live births per 1000 people of population per year Mortality—The number of deaths per 1000 people of population per year Growth rate of population—The difference between the birth rate and death rate Differences: 

Sexual and asexual reproduction  Spermatogenesis and Oogenesis  Sperm duct and fallopian tube  Sperm and ovum

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