MRSM PDRM

Name : Muhammad Fikri bin Ahmad FauziCollege no. : 29082Class :

Contents

Contents Page

Appreciation 1

The world through our senses 2

Sense organ ability 3

The human nervous system 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.

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SENSE ORGANS’ ABILITY

Sensory organ Stimuli detected Main function(a) Skin Touch, pressure, pain,

heat, coldOrgan 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.

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Nervous system

4

Skin

1. The skin is made up of two layers- the epidermis and the dermis.

Nervous System

Central nervous system Nerves

BrainSpinal Cord

Sensory nerves

Motor Nerves

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.

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-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.

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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.

7Nervous pathway for detecting taste:

Food(stimuli) Saliva dissolves food Chemical in food stimulate taste

buds Taste buds send impulses to brain The brain interprets the

impulses

o Different areas of the tongue are especially sensitive to different taste

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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 Chemical

stimulate the sensory cells 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

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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

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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 humorpupileye lens vitreous

Humorretinaoptic nervebrain

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The structure of the eye

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Defects of Vision

Long-sightedness Short-sightedness Astigmatism Color blindness Optical illusion Blind spot

There are two kinds of vision:

Stereoscopic vision Monocular vision

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