Structural Organization Of Life The Discovery of Cell and Cell Theory Discovery of Cell In 1665, an English biologist Robert Hooke invented frst compound microscope and observed the sections o corks and leaves under this microscope. He noticed in them small bo like chambers o same si!e "hich he called #cells$. %ter this, biologists observed di&erent organisms under the microscope. 'he( ound that structure o cells "as comple.
Cell Theory In 1)th centur(, the compound microscope "as highl( advanced and biologists observed things *ust a micrometer apart. %ter this, a series o discoveries started, "hich provided basic inormation or cell theor(. 1. In 1+1 - , Robert ro"n discovered nucleus in cells o plants. /. In 1++, a 0erman botanist athias 2cheiden observed that all plants "ere made up o cells. . In 1+), 'heoclor 2ch"ann obsrved that the bodies o o animals "ere made up o cells "hich "ere similar to plant cells. 3. 'hus, 2chleiden and 2ch"ann ormulated the #4ell 'heor($. %ccording to this, all organisms are made up o cells. 5. In 1+3, . 7urkin*i gave the name #7rotoplasm$ to the things ound inside the cells. %t that time, cell "as considered as a bag o thick dense substance containing a nucleus. 8ater on, resolving po"er and 9ualit( o microscopes "ere highl( improved. 2ection cutting o tissues and cells and their staining became easier and better. It revealed that cell "as not a simple mass o granular substance: instead it contained man( sub cellular bodies called #;rganelles$. Each organelle has a defnite *ob in the cell. 6. Human is made up o about 6 trillion cells.
Salient Features of Cell Theory
1. %ll animals and plants are made up o cells and cell products. %mong these some organisms are unicellular and some are multicellular. /. 4ell is structural and unctional unit o living organisms. . >e" cells come rom the divisions o pre?eisting cell.
Electron Microscope
'his is the most advanced orm orm o microscope. microscope. Its resolving resolving po"er is /5 times or more that o a compound microscope. In this microscope, a beam o electrons under high voltage is passed through the ob*ect and its image is re@ected on to a screen through an electro magnetic lens to make a photograph. ABiagramC Dith the help o microscope, an( ob*ect an be magnifed up to /5, its original si!e.
Comparison of Light Microscope and Electron Microscope Light Microscope 'he radiation radiation source source is light so it is called light light microscope. microscope. Davelength o light is 3 - nm. aimum resolution is / nm. aimum useul magnifcation is F 15 "ith e(e. 8enses are used.
Electron Microscope 'he radiation radiation source source is beam o electrons, electrons, so it is called Electron icroscop icroscope. e. Davelength o beam o electrons is .5 nm. aimum resolution is .5 nm. aimum useul magnifcation is F. /5, on screen as image or photograph. Electromagnets are used.
Structure of Eukaryotic Cell 2tructure o 4ell 'here are are t"o t(pes o cellsG cellsG 1. 7rokar(otic cell /. Eukar(otic 4ell 7rokar(otic cell lacks a membrane bound nucleus and membraned organelles e.g. bacterial cell "hile eukar(otic cell has a membrane bound nucleus and membraned organelles e.g. cells o plants and animals. Dith the help o light microscope and electron microscope, a t(pical Eukar(otic cell sho"s the ollo"ing structural details. ABiagramC 1. 4ell Dall /. 4ell embrane . >ucleus 3. 4(toplasm 1. 4ell Dall It is the outer most boundar( o plant cells. It is rigid and non?living. It is chemicall( composed o 4ellulose. 'he cell "all o ungi is made up o 4hitin. 'he "alls o some cells are thick and "alls o some cells are thin.
It is a thin membrane "hich is also called 7lasma membrane. It is present in cells o all plants and animals. It is outer most boundar( o animal cell "hile in plant cells: it is present inner to cell "all. oth nucleus and c(toplasm are surrounded b( cell membrane. %ccording to @uid mosaic model, cell membrane is composed o t"o la(ers o lipids in "hich protein molecules are partiall( or completel( embedded.
ucleus It is most important and distinct part o the cell. It is present in center o the animal cell "hile in plant cell it is pushed on one side due to large central vacuole. It is also surrounded b( a membrane "hich is called membrane. nder microscope, it to be doubled and nuclear electron appears porous. 1. 'he number o chromosomes is fed or each species. 'his number is called diploid number A/nC. E.g human=s cell has 36 chromosomes, cell o Radish has 1+ chromosomes, and cell o union has 16 chromosomes. /. 4hromosomes are composed o protein and B>%. . In the nucleolus Aplural, >ucleoliC ribosomal R>% is ormed "hich helps in the ormation o ribosome. 3. 4(toplasm It is viscous opa9ue substance. It is present bet"een nuclear membrane and cell membrane. In a living cell, man( t(pes o organelle o di&erent si!es and shapes are ound. It contains man( insoluble granules o storage substances. 'here are also present organic compounds like carboh(drates, proteins, lipids AatsC, en!(mes and inorganic compounds like "ater and salts.
;rganelles in 4(toplasm
itochondria
'he( re oval or rod like in shape. 'heir membrane is doubled. ;uter membrane is smooth "hile inner membrane has enolding in the mitochondrial matri. 'hese enolding are called cristae. 'he cristae bear small rounded bodies "hich are called particles. 'here are about one million elementar( particles in one mitochondrian. 'he( are involved in oidative phosphor(lation. 'he( also have man( respirator( en!(mes. >umber o itochondria 'heir number is di&erent in di&erent cells o di&erent animals. In more active cells, their number is more than 1 e.g. liver cell.s 'he cells o ear lobes have a e" number o mitochondria.
It is also called granular endoplasmic reticulum because ribosomes are attached on it.
'hese are second t(pe o plastids. 'hese are o various colours other than green. In plants, colours other than green are due to chromoplasts. 'hese are present in the petals o the @o"ers and in the ripened ruit.
Bi&erence bet"een 7rokar(otic 4ell and Eukar(otic 4ell
7rokar(otic 4ell 'he organisms made o prokar(otic cells are called prokar(otes e.g. bacteria and c(anobacteria.
'hese cells lack a membrane bound nucleus. 'he hereditar( material AB>%C is ound in c(toplasm. 'hese cells lack membrane bound organelles. Ribosomes are o small si!e in and reel( scattered c(toplasm. 4ellulose is absent in cell "all, rather it is made up o peptido?gl(can or murein. 'hese cells are simple and o smaller si!e Aaverage diameter .5 - 1 nmC Eukar(otic 4ell 'he organisms mae o Eukar(otic cells are called Eukar(otes, e.g. animals, plants ungi and protists. 'hese cells have a membrane bound nucleus: and hereditar( material is ound inside the nucleus. 'hese cells have membrane bound organelles. Ribosomes are o large si!e and are present in endoplasmic reticulum ree in c(toplasm. 4ellulose is present in cell "all o plant cells. 'he cell "all o most o ungi is composed o chitin. 'hese cells are comple and o larger si!e A%verage diameter 1?1nmC itosis
It is that cell division in "hich the number o chromosomes in both daughter nuclei remains same as in parent nucleus. ABiagramC Events o itosis itosis has the ollo"ing phasesG 1. 7rophase /. etaphase . %naphase 3. 'elephase 5. 4(tokinesis
7rophase 1. In this phase, coiling o chromosomes starts and their length decreases but diameter increases. It means that chromosomes become shorter and thicker, this process is called condensation. /. icrotubules arrange to orm a structure called spindle. . In animal cell, there are also present centrioles on both poles o spindle. uclear membrane is broken do"n. >ucleolus disappears and chromosomes scatter over the spindle fber. 6. Each chromosome consists o t"o similar threads like structure called chromatids, these chromatids are united to each other b( means o centromere. etaphase 1. 'he chromosomes arrange themselves on e9uator o the spindle to orm an e9uatorial plate. In this condition, chromosomes become more visible. /. 'he chromosomes are attached at their centromere to one spindle fber rom each pole. %naphase 1. uclear membrane reorms and nucleolus appears too. 'hereore t"o nuclei are ormed. Each daughter nucleus has the same number o chromosomes as the parent cell.
4(tokinesis 'he division o c(toplasm is called c(tokinesis. It begins at the last stages o nuclear division. In plant cell, c(toplasm divides b( ormation o cell plate "hich is also called phragmoplast. It graduall( etends out"ard and fnall( t"o daughter cells are separated. In animals, c(toplasm divides b( urro"ing. Buring this, there occurs in"ard pinching o cell membrane resulting into t"o daughter cells. In mitosis, t"o daughter cells are ormed rom one parent cell "hich are identical to their parent cell. 2ignifcance o itosis 1. itosis occurs in all t(pes o somatic cells. /. Baughter cells ormed as a result o mitosis have same number o chromosomes as that o parent cell. In this "a(, all cells o bod( o an organism have same number o chromosomes. . J(gote divides b( mitosis to orm embr(o and ater hatching or birth, mitosis continues up to maturit( o an individual. 3. itosis also results in gro"th and repairing o damaged or "orn out tissues. 5. Healing o "ounds is also due to mitosis
eiosis
It is that t(pe o cell division in "hich c(toplasm and nucleus divides t"ice and as a result o this, our daughter cells are ormed and chromosome number is reduced to hal. It means that one diploid A/nC parent cell divides to orm our haploid AnC daughter cells. eiosis consists o t"o sub divisionsG 1. eiosis I /. eiosis II 1. eiosis I It has ollo"ing stagesG 7rophase I
1. It is length( than prophase o mitosis. It is ver( important phase. It is divided into fve stages during "hich there is continuous condensation o chromosomes. /. 'he important process o this phase is s(napsis in "hich homologous chromosomes pair "ith each other length "ise. . Each pair consists o our chromatids or t"o chromosomes. 3. %ter s(napsis, the process o crossing over takes place. In this, homologous chromosomes echange their chromatids parts at certain places. 5. %t end o this phase, nuclear membrane breaks up. >ucleolus disappears and chromosomes scatter over the spindle. 6. 8ike mitosis, mitotic apparatus is also ormed here. ABiagramC etaphase I 1. 'he chromosomes arrange on scatter o the spindle. /. Here, homologous bivalents arrange at e9uatorial plate o spindle. . ;nl( one spindle fber is attached to each chromosome. %naphase I 1. Homologous pairs o chromosomes are separated. /. 2pindle fbers contract. . 4hromosomes begin to move to"ards the opposite poles. 3. 'his phase is di&erent rom metaphase o mitosis because hal the number o chromosomes moves to"ards each pole and each chromosome still has t"o chromatids. 'elephase I 1. Hal the number o chromosomes reach at opposite poles. /. 4hromosomes again increase their length. . >ucleolus reappears. >uclear membrane is reormed and in this "a( t"o daughter nuclei are ormed. 3. >o" c(toplasm divides and t"o daughter cells are ormed. Each cell is haploid AnC.
/. eiosis II It is similar to mitosis. 'he haploid cells ormed in meiosis I pass through phases o meiosis II and ultimatel( our haploid AnC daughter cells are ormed. 'hese cells ater"ards change into spores Ain plants or gametes AanimalsC 2ignifcance o eiosis 1. eiosis takes place onl( in germ mother cells "hich orm gametes or spores. /. It maintains the chromosome number o a species constant generation ater generation. . I gametes had the same number o chromosomes as in somatic cells, the number o chromosomes "ould have doubled ater each generation in a species. 3. 'he number o chromosomes is constant or each species. Buring meiosis: gametes Aboth andC ormed are haploid. 5. 0ametes unite to orm a diploid !(gote. 6. Buring meiosis, pairing o chromosomes takes place "hich is called s(napsis. . Echange o genetic material occurs during meiosis. In this "a( variations are produced "hich are ra" material or evolution.
'issues
'issues % group o cells "hich perorm same unction is kno"n as tissue. 'he tissues are divided into di&erent t(pes on the basis o their orm and structure or unction. 7lant 'issues
i. eristematic or embr(onic tissues ii. 7ermanent 'issues i. eristematic 'issues 1. 4ells o this tissue have abilit( to divide. /. 4(toplasm is dense nd nucleus is big in these cells. . acuoles are smaller i present other "ise absent. 3. %ll cells are identical. 5. 'here are no intercellular spaces. 6. 'heir "alls are thin and nucleus is present in centre o cell. . 'hese tissues ound on ape o root or shoot are called apical meristems. 'he cells o these tissues divide: and redivide to add primar( tissue or elongation o setm or root. 'his t(pe o gro"th is called primar( gro"th. +. eristematic cells are also ound on the lateral sides o roots and stems as lateralAcambiumC or intercalar( meristem, and these add, secondar( tissues. In this "a(, thickness o stem or root is increased. 'his t(pe o gro"th is called secondar( gro"th. ii. 7ermanent 'issues 'he cells o this tissue lack the abilit( to divide and the( originate rom meristems. 'hese are given belo"G a. Epidermal 'issues b. 0round 'issues AaC Epidermal 'issues 1. 'he( are ound as the outermost covering o lea, stem or root. /. 'here are non intercellular spaces. . 4ells are rectangular in shape. 3. In the epidermal tissues o stem and leaves, there are small openings called stomata or gaseous echange. AbC 0round 'issues
1. ost o the portion o bod( o herbaceous plants consists o ground tissues i.e. parench(ma. /. 'he( are thin "alled. . 4ells are large in si!e. 3. 4ells sometimes ma( develop the abilit( to divide. 5. 'heir main unctions are to prepare and store ood and "ater. 2upporting or echanical 'issues 'hese provide strength @eibilit( to the plant. 'he( are o ollo"ing t"o t(pesG a. 4ollench(ma 'issues b. 2clerench(ma 'issues AaC 4ollench(ma 'issues 1. 'hese consist o living cells. /. 'heir "alls are not uniorml( thickened. . suall( "alls are thickened at angles. 3. 'hese are more @eible or elastic than sclerench(ma. 5. 'hese tissues are ound in stem, in midrib o leaves and in corte o petiole. AbC 2clerench(ma 'issues 1. 'hese consist o dead cells. /. 'heir "alls are highl( thickened due to deposition o lignin. . 8ignin provides hardness and strength to the cell. 3. 'hese cells are "ithout protoplasm. 5. 2clerench(ma cells are o t"o t(pes, 2tone cells having uniorml( thick cell "alls: ound in testa o seeds.
'hese are the tissues "hich consists o t"o or more than t"o t(pes o cells. ut all cells perorm a common unction. 'hese 'issues are o ollo"ing t(pesG F(lem 'issue 1. 'his vascular tissue transports "ater in the plants and provides strength to the plant. /. In this tissue, there are present (lem parench(ma and t"o t(pes o thick "alled dead cells. 8ong cells "hich are called vessel elements or cells. 'he( are *oined together to orm long pipe?lines. 'hese transport "ater rom roots to leaves. 2pindle shaped cells, "hich are called tracheicts. 'hese provide strength to root and shoot etc. . F(lem conducts "ater in one direction that is rom roots to"ards the stem and leaves. 7hloem 'issues 1. 'his vascular tissue transports ood in the plants. /. It helps in t"o directional conduction o ood material i.e. rom leaves to roots and vice?versa. . 'his tissue mostl( consists o living cells. 'here are three t(pes o cells AaC 7hloem 7arench(ma AbC 2ieve 'ube 4ells AcC 4ompanion 4ells AaC 7hloem 7arench(ma 'hese cells store surplus "ater and ood. 'he( can start to divide "hen needed. AbC 2ieve 'ube 4ells 'heir end "alls have small pores called sieve plates. 'hese cells *oin to orm long pipelines, "hich are called sieve tubes. 'here is no nucleus in these cells. 'heir main unction is to transport ood. AcC 4ompanion 4ells
In some plants, each sieve tube cell is accompanied b( a companion cell. 'he companion cell has a nucleus. 'he corn cell controls the movement o ood through sieve tubes. %nimal 'issues erve 'issues 1. Epithelial 'issues 1. these are ound as outer most la(ers o an organ or as lining o bod( invaginations. /. 'heir cells are long and @at. . 'hese ma( orm one or more la(ers o epithelial tissues o skin "hich is called s9uamous epithelial cells. 3. 29uamous Epithelium provides protection to skin. 5. 2ome cells are cubical in shape and kno"n as cuboidal epithelial cells. 6. 4uboidal epithelial cells rom the lining o glandular ducts and help in the production o cell secretions. . 2ome cells are small and elongated "hich are ound at certain places in the inner lining o di&erent organs and secret *uice. 'hese are called columnar epithelial cells e.g. cells o gastric glands in stomach "hich secrete the gastric *uice. +. 2ome columnar cells have cilia at their ree surace. 'hese are called ciliated columnar epithelial cells e.g. cells present in trachea. Bue to movement o these cilia, mucous and other materials are epelled. /. 4onnective 'issues 1. 'his tissue is made up o semi @uid matri. /. 'hese matries contain a variet( o cells and fbers. . 'hese tissues provide support to di&erent bod( parts and bind them together. 'hese also protect the organs rom germs and help in the production o blood cells.
3. 'hese are o t"o t(pesG 2ot connective tissues e.g. att( tissues and tendons. Hard connective tissues e.g. cartilage and bone. 5. lood is also a special connective tissue "ith cells suspended in the @uid medium. It transports materials in the bod(. /. uscular 'issues 1. 'his tissue is made up o special contractile cells or fbers. /. 'he cells are elongated and are called muscle fbers. . 'hese cells have the abilit( to contract and rela "hich results in movements o bod( and the organs. 3. ervous 'issues 1. 'hese are composed o nerve cells "hich are called neurons. /. Each neuron consists o a cell bod(, aon and dendrites. . 'hese productive nerve impulse to conduct messages. 3. ( this tissue, di&erent bod( parts have coordination "ith each other.
5. 'his tissue also orms brain and spinal cord
nicellular ;rganism A%moebaC
'he organisms consisting o onl( one cell are called unicellular organisms e.g. %moeba, 7aramecium etc. %moeba 1. It is mostl( ound in resh "ater pond or pool. /. In the ponds, it is ound moving about around the "eeds and stones. 2ome species are ound in the moist soil. . %moeba is a large protist. 3. It does not have the permanent shape. 5. Its si!e is about the end o pin or it measures about ./5mm. 'hereore it is observed under the microscope. 6. Its structure is ver( simple. . It consists o nucleus and c(toplasm, "hich are surrounded b( a cell membrane. +. 4ell membrane protects it. ). 4(toplasm is divided into t"o parts. ;uter clear and transparent part is called ectoplasm "hile the inner, viscous, translucent and granular part is called endplasm. 1. Endoplasm contains ood vacuoles o di&erent si!es. 'hese ood vacuoles help in the digestion o ood. 11. 'he ood o %moeba consists o microbes present in the "ater o pond. 1/. 4ontractile vacuole maintains the concentration o "ater in the bod(. It removes surplus "ater out o the cell. 1. In %moeba, the echange o gases and removal o "aste. 13. In %moeba, there are also present mitochondria, golgi bodies and ribosomes. 15. >ucleus changes its place "ith the movement o the organism. ABiagramC
ulticellular ;rganism Arassica 7lantC
ulticellular ;rganism 'he organisms consisting o man( cells are called multicellular organism. e.g. rassica 7lant, rog, man etc. diagramK rassica 7lant Austard 7lantC 1. 'his plant is so"n in "inter and at the end o season, it produces seeds and then dies. /. 'his is an annual plant. . %n oil is etracted rom seeds o this plant "hich is kno"n as mustard oil. 5. 'he scientifc name o this plant is rassica 4ampestris. ABiagramC >on?Reproductive 7arts or egetative 7arts 'hese parts do not directl( take part in seual reproduction e.g. root, stem, branches and leaves. Reproductive 7arts 'hese parts directl( take part in seual reproduction e.g. @o"er, ruit and seed. Root o rassica 'he root is that part plant "hich is present inside the soil. It is produced rom radical o seed. 'he frst ormed root is called 7rimar( root. Buring its gro"th, it gives o& secondar( and tertiar( root. Each root has a root cap at its tip or ape. ehind the root cap, root hairs are present "hich absorbs "ater and salts rom the soil. Roots also anchor the plant frml( in the soil. ABiagramC Internal 2tructure o Root o rassica Dhen transverse section o root o rassica is observed under the microscope, the ollo"ing parts are ver( prominent.
Epidermis It is outermost and protective la(er. It is single celled. 2ome cells gro" out"ard to orm root hair. 4orte It is present inner to epidermis. It is made up o several la(ers o thin "alled living cells Aparench(ma cellsC. 'here are present intercellular spaces. 'hese cells store ood. Endodermis it is the innermost la(er o corte. 'here are no intercellular spaces. 'here are thickenings o special materials around the cell "hich check di&usion o "ater rom (lem to corte. 7eric(cle 'he la(er present inner to endodermis is called peric(cle. 'here are also no intercellular spaces. %ll the branches o roots arise rom peric(cle. ascular undles F(lem is present in middle o root "hich etends to peric(cle in the orm o our ra(s and controls one "a( transport o "ater and salts. In bet"een the (lem ra(s, phloem bundles are present "hich transport ood in t"o directions. 2tem o rassica 'he stem is that part o the plant "hich gro"s above ground. It arises rom plumule o seed. It is herbaceous and branched. It bears leaves and @o"ers. 'he part o stem or its branch rom "here a lea arises is called node. 'he part bet"een t"o nodes is called internode. the important unction o stem is the conduction o prepared ood rom leaves to other parts and that o "ater absorbed rom roots to leaves. It supports leaves, @o"ers and ruits like a pillar. It keeps the leaves in such a position that the( can get light to prepare ood. ABiagramC Internal 2tructure o 2tem o rassica Dhen transverse section o stem o rassica is observed under the microscope, ollo"ing parts are visible. Epidermis
It is the outermost protective la(er o stem. ;uter to epidermis, there is la(er o cutin "hich reduces loss o "ater rom stem. 'he cells are compactl( arranged and there are no intercellular spaces. 4orte It is inner to epidermis. It is made up o man( la(ers o parench(ma and collench(ma tissues. 'he main unction o corte is storage o "ater and ood. Endodermis It is innermost la(er o corte. It is not prominent in stem. It allo"s suitable 9uantit( o "aer to enter corte rom (lem. 7eric(cle It is in the orm o bundles in bet"een the endodermis and vascular bundles. It is composed o sclerench(ma cells. It orms bundle cap. ascular undles In stem, vascular bundles are arranged in the orm o ring. ascular bundle consists o phloem and (lem. 7hloem is to"ards outside and (lem is to"ards inside.
5. In the middle o lea there is a thick midrib. 6.
oth t(pes o cells have chloroplasts containing chloroph(ll. 2o, photos(nthesis takes place here. 'he unction o mesoph(ll is to manuacture ood or the plant. ascular 'issue It consists o midrib and veins. 'he midrib is bundle. pper part o midrib is (lem and lo"er part is phloem. 7eric(cle and endodermis surround this bundle. esides this 8amina has other bundle "hich are called veins.
insects and are transerred rom one @o"er to the other. 'his process is called pollination. 0(noecium It is the inner most part o @o"er. It is emale reproductive part. It consists o t"o carpels, "hich are used. Each carpel has three parts. 'he basal s"ollen part is called ovar(. 'he stalk like part above the ovar( is called 2t(le. 'he top o st(le is some"hat s"ollen and it is called 2tigma. ;ver( contains man( ovules. ;vules are ripened to orm seeds "hile ovar( is ripened to orm ruit. 'he ruit o rassica is called 2ili9ua.
ear the vomerine teeth, internal nostrils are present on the roo o the buccal cavit(. 'hese open out"ards into eternal nostrils. ehind them,
t"o large bulges indicate the position o e(es. 'he tongue o rog is stick(. 'he tongue is attached at anterior end o buccal cavit(. 'he posterior end o tongue is ree and bifd. the rog eeds on di&erent insects. 'o capture its pre(, it suddenl( thro"s its tongue on to the pre(, "hich sticks to the tongue and is brought to the buccal cavit(, "hen the tongue is dra"n back. >ear the maillar( *oints, pair o opening o eustachian tubes are present. In male rog, there is also, present a pair o opening o vocal, sacs on the lateral side o @oor o the buccal cavit( "hich help the croaking. uccal cavit( narro"s, posteriorl( to orm phar(n. 'he digestive s(stem, respirator( s(stem and ears are linked to phar(n. In posterior part o phar(n, there is another opening called 0lottis. 'his leads to lungs through tachea. It closes at the time o digestion o ood but remains open "hen animal is respiring. ABiagramC ;esophagus, 2tomach and Intestine 7har(n leads into a small but "ider tube called oesophagus or gullet. 'he oesophagus opens into the stomach. 'he anterior end o stomach is called 4ardiac end "hile the posterior end is called 7(loric end. 'he "alls o stomach are muscular and glandular.
'he muscles o "alls o stomach contract and rela, b( "hich ood is broken do"n into tin( pieces. 'he secretions o stomach have di&erent en!(mes "hich help in chemical digestion. In stomach, digestion o protein o ood is started. %ter stomach, frst part o intestine begins "hich is called duodenum. 'he ducts rom liver and pancreas open into the duodenum. 'hese ducts bring *uices rom these glands. 'he second part o intestine is Ilium are called 2mall intestine. 'he secretion o pancreas is called 7ancreatic uice. 7ancreatic *uice enters the bile duct b( small duct. 'his *uice digests the ood and brings in such orm "hich can be absorbed b( the blood through intestine. Bigested ood is absorbed b( illium and surplus "ater is absorbed b( recturm. Remaining undigested ood is epelled though cloacal aperture. % membrane keeps the intestine intact at a place and prevents strangulation o small intestine. 'his membrane is called mesenter(. Respirator( 2(stem o
ABiagramC 7ulmonar( Respiration 'he echange o gases through lungs is called pulmonar( respiration. In this process, rog keeps its mouth closed. %ir reaches buccal cavit( through nostrils. >ostrils are closed @oor o buccal cavit( is raised: glottis opens, and air is pushed into the lungs. 'he intake o air is called inspiration. In rog, there is a pair o balloon shaped lungs. Each lung consists o small thin "alled chambers called alveoli "hich greatl( increase the surace area o the lungs. ;n each alveolus, there are man( blood capillaries. Dhen lungs are flled "ith air, then echange o gases occurs bet"een blood and air in lungs at the site o alveoli. Buring this, the echange o gases occurs bet"een blood and air present in buccal cavit(. %ter this air is removed rom the lungs.
Heart is conical organ. It is muscular. It has three chambers. It is present in the bod( cavit( bet"een the oesophagus and sternum. 8ike a pump, it contracts and is relaes. %s a result o this, blood continuousl( circulates in the bod(. 'he heart is surrounded b( a membrane "hich is called pericardial "hich protects the heart. A
%rterial 2(stem o
enous 2(stem 'he blood vessels "hich bring the blood rom di&erent bod( parts, back into the heart are called veins. 'he s(stem containing o veins is called enous s(stem. ear the liver a branch o abdominal vein combines "ith it. 'hen it enters the liver and divides and redivides to orm capillaries. 'he, blood entering the liver through hepatic portal veins goes to the post caval b( means o hepatic veins. 'he blood rom post caval goes to heart through sinus venosus. 'he blood coming back into the heart is o t"o t(pes.
;(genated blood "hich comes rom lungs b( pulmonar( veins. Beo(genated blood rom all parts o the bod( enters sinus venosus through precavals and post caval and then enters the right atrium. ABiagramC 8(mphatic 2(stem o
Reproductive 2(stem o ervous 2(stem o ervous 2(stem /. 7eripheral >ervous 2(stem . 2(mpathetic >ervous 2(stem 4entral >ervous 2(stem It consists o brain and spinal cord. ABiagramC rain rain is enclosed in protective la(ers and is located in cranium or brain case, "hich is ma*or part o skull. ABiagramC rain is divided into three partsG AaC
'his is central part o brain. 'his is associated "ith e(es and vision. AcC Hind rain 'his is the posterior part o brain. It controls and coordinates bod( movements and maintains balance o the bod(. It also controls respiration, circulation, taste and digestion. 2pinal 4ord 'he posterior part o the brain is continuous "ith spinal cord. It runs through the vertebral column. 'he spinal cord controls the movements o trunk region. 7eripheral >ervous 2(stem It consists o nerves. 'hese nerves connect the central nervous s(stem A4>2C "ith various parts o the bod(. 2ome nerves originate rom brain. 'hese are called cranial nerves other nerves originate rom spinal cord. 'hese are called spinal nerves. In rog, there are 1 pairs o cranial nerves and ) or 1 pairs o spinal nerves. 4ranial asicall(, nerves are o three t(pesG 2ensor( >erves 'hese take messages rom sensor( organs to 4>2. otor >erves 'hese take messages rom 4>2 to glands and muscles. ied >erves 'hese do both above mentioned unctions. 4ranial >erves In these nerves, frst, second and eight pairs are sensor( nerves "hich are associated "ith senses o smell, sight and hearing. 'hird, ourth and sith pairs are motor nerves "hich carr( message rom brain to the e(e. >ine and ten pairs are mied nerves, "hich are supplied to *a", ace, tongue and heart. 2pinal >erves 'hese are all mied nerves. 'hese control unctions o di&erent organs. Ear o
2tructure o Ear o
