MRSM PDRM
Name College no. Class
: : :
Muhammad Fikri bin Ahmad Fauzi 29082
Contents
Contents
Appreciation The world through our senses Sense organ ability The human nervous system
Page
1 2 3 4,5
Skin
6,7
Tongue
8,9
Nose
10.11
Ears
12,13
Eyes
14,15
I want to say thank you to my parents for supporting me on financial and moral. Because of that, I can finish my folio very well. Lastly, I want to say thank you to my friends that always help me and also share some information. Not forgotten for all parties that involved. Thank you very much.
The World Through Our Senses
Our senses detect stimuli and we respond. Human have receptors or sense organs such as:
SKIN - responds to touch, pressure, pain, heat and cold. TONGUE - responds to chemical in our food and drink. It gives us our sense of taste NOSE - responds to chemical in the air. It gives us our sense of smell. EARS - respond to sound vibrations and movements. They give us our sense of hearing and our balance. EYES - respond to light rays. They give us our sense of sight.
1
SENSE ORGANS’ ABILITY
Sensory organ (a) Skin
Stimuli detected Touch, pressure, pain, heat, cold
Main function Organ for touch
(b) Nose
Chemicals
Organ for smell
(c) Tongue
Chemicals
Organ for taste
(d) Ear
Sound
Organ for hearing
(e) Eye
Light
Organ for sight
2
The Human Nervous System
1.
The nervous system is responsible for detecting stimuli and changes in the environment and sending the information to the brain for interpretations.
2.
The brain then sends out instructions to the relevant parts of the body for action to be taken.
3.
The information and instructions are sent out in the form of nervous impulses along nerves.
4.
The nervous system consists of the brain, the spinal cord and the nerves.
5.
The brain and the spinal cord form the central nervous system.
6.
The nerves which send nervous impulses from the sensory organs or receptors to the brain are called the sensory nerves.
7.
The nerves which carry nervous system from the central nervous system to the muscle or glands for carrying out the responses are called the motor nerves.
3
Nervous system
Nervous System Central nervous system
Brain
Nerves
Spinal Cord
Sensory nerves
4
Skin
Motor Nerves
1.
The skin is made up of two layers- the epidermis and the dermis.
2.
The epidermis is a very thin layer of dead cells which protects the surface of the body.
3.
The dermis is a layer consisting of structures such as living cells, blood capillaries, sweat glands, nerves and nerve ending.
4.
The skin is a sense organ helping the body to know what is happening in its surrounding.
5.
The nerve endings or receptors in the skin detect stimuli.
6.
The sensitivity of the skin depends on two factors:
(a) The thickness of the epidermis - the thinner the epidermis, the more sensitive is the skin. (b) The concentration of the receptors – the more receptors in the skin, the more sensitive is the skin.
5
-Pain receptors are at the skin surface. They are branched and respond to intense stimuli.
-Some touch receptors are attached to the base of our hair. So you can feel it they are being pulled. -Pressure receptors are in the fatty layer. It is used to detect pressure exerted on the skin. -Heat receptors are located below the epidermis. It detects heat or any rise of temperature. -Cold receptors are also located below the epidermis. It detects a cold substances or any fall in temperature.
6
Tongue
1.
Your senses of taste and smell are closely linked. They are both chemical senses.
2.
What things can you taste? -You can only taste sweet, sour, bitter, and salty things. People think that they can taste other things but they are actually using their sense of smell.
3.
The sensors that give you your sense of taste are found in little grooves on your tongue. They are call taste buds. Each taste bud can only taste one taste.
4.
The different types of taste buds are found in particular areas on the tongue.
5.
The taste buds send nervous impulses along the nerves to the brain for its interpretation.
6.
When food is placed in the mouth, the saliva dissolves the food and the chemicals stimulate the taste buds.
7
Nervous pathway for detecting taste:
Food(stimuli) Saliva dissolves food
buds Taste buds send impulses to brain
Chemical in food stimulate taste
The brain interprets the
impulses
Diffe rent areas of the tongue are especially sensitive to different taste o
8
Nose
Our nose also senses chemical but it is thousands of time more sensitive than your sense of taste.
Smells are chemical in the air. The chemical dissolve in the moist lining of your nose. They stimulate sensors in your nose to send impulses to the brain. The brain interprets these impulses as different smells. The nasal cavities have glands which produce a sticky fluid called mucus. A person having a cold cannot smell well. This is because the sensory cells are covered with a lot mucus and not much chemicals can reach and stimulate the sensory cells.
The nervous pathway can be summarized as follows:
Chemical enter the nose Chemical dissolves in mucus stimulate the sensory cells
Chemical
The sensory cells produce nervous impulses
Nervous impulses are sent along the nerves to the brain The brain interprets the impulses as a certain smell 9
10
Ears
The air around us is full of sound waves. You ears work by converting these sound waves into nerve impulses. This show it happens:
•
The outer part of your ear funnels the sound waves into the ear canal
•
The sound waves travel along the ear canal to the eardrum.
•
The eardrum starts to vibrate when sound waves hit it
•
The vibrations are passed on to 3 little bones called the ossicles
•
The ossicles pass the vibrations on to the inner eardrum or oval window
•
When oval window vibrates it causes fluid in the cochlea to move
•
Inside the cochlea are lots of tiny, sensory hairs. Movement of the fluid sets these hairs vibrating. They send off nerve impulses to the brain
•
The brain interprets these impulses as sounds
11
12
Eye
►
The eye is a sensory organ for light. We see things with our eyes.
►
Each eyeball is situated in a socket within the skull.
►
Each eyeball is moved by three pairs of eye muscle.
►
The front of each eye is protected by an eye lid.
►
The eye is washed by tears produced by tear glands.
►
A duct drains the tears from the eye to the throat.
►
The pupil (hole) in the centre of the eye allows light to enter the eye.
►
The colored part of the eye called the iris is a continuation of the choroids
►
The white of the eye is a continuation of the sclerotic.
►
The eye is made up of many parts, and each part is designed to help the eye to see.
The nervous pathway is as follow:
Corneaaqueous humor pupileye lens vitreous Humor retinaoptic nerve brain
13
The structure of the eye
14
Defects of Vision
• • • • • •
Long-sightedness Short-sightedness Astigmatism Color blindness Optical illusion Blind spot
There are two kinds of vision:
• •
Stereoscopic vision Monocular vision
.
15
