World Through Our Sense

8/2/2019 World Through Our Sense

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Contents


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The Sensory ofThe Organ .


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The Sensory Organs !

The sensory organs > enable an organism to detect changes that occur in its

environment .

Five main sensory organs in humans and stimuli they respond to are shown in table

below >

Sensoryorgan Sense StimuliTouch Heat , pressure , pain ,

cold , touch

Smell Chemical subtances

Taste Chemical subtances

Sight Light

Hearing Sound

FunctionEnable us to feel and identify t

size , texture and shape of the

object

Detect various temperatureRemove waste substances in th

form of sweat

Detect various smell

Taste different flavoured prod

To see objects

Detects sound and help to bala

the body


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The pathway from stimulus to response >

Stimulus Receptors in sensory organs

Sensory nerves Motor nerves

Effectors Response


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Senseof

Touch


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Sense Of Touch !( skin)*the largest sensory organ in human body .*Very sensitive to touch .*The structure of the skin .*The skin consists of two main layers > epidermis & dermis .*Our body have different types of receptors >pain receptors

> touch receptors

> heat receptors

> cold receptors

> pressure receptors

*The receptors are connected to nerves .

*When a receptor is stimulated , an impulse is produced and sent through the nervous

system to the brain to be evualated .

*The sensitivity of skin > different parts of body have different degrees of sensitivity .

a) Thickness of the epidermis

> The thicker the epidermis , the lower the sensitivity of skin

>The thinner the epidermis , the more the sensitivity of skin .

b)The number of receptors

>The larger the number of receptors , the higher the sensitivity of skin .

> The smaller the number of receptors , the lower the sensitivity of skin .

c) Example : more sensitive >

: less sensitive >

Lips FingertipsNeck Back o

ha

toungue

ElbowSoles ofthe feet

LegsBack ofthe body


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* Advantages >

>

Reading Braille

> the blind use their fingertips to identify letters and

read Braille .

> this book used raised dots to represent numbers and

words .

The injection spot on the body

> doctors usually give injection at the forearm or the

hip .

> this area have few receptors and thicker epidermis .

> hence , less pain is felt by the patient .


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Sense oSmell


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Sense of Smell ! ( nose)# Smell > chemical present in the air

> chemical substances that give out air : food

: perfume

: flower

# Smell receptors > located at the roof of nasal cavity to allow the smell receptors have

the maximum exposure to the air current .

# Nervous pathway for detecting smell >

The brain interprets the impulses and the smell is

identified

Smell receptors are simulated

The smell receptors produce

nervous impulses

Chemical dissolve in the mucus

Chemical in the air enter the nasal cavity

Nervous impulses are sent to the brain


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# The Sensitivity of Smell > higher in animal :

Rat cat dog


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Sense oTaste


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Sense of Taste ( toungue )Sensory receptors . taste buds on the surface of tongue.Main types of taste . sour , salt , sweet and bitterTaste buds for detecting different types of taste are concentrated at different

parts of toungueGood taste of food > can only detected if the food is in the form of liquids or can

be dissolved by the salivaNervous pathway for detecting taste >

The brain interprets the impulses and the taste is identified .

Nervous impulses are sent to the brain .

Sensory cells produce nervous impulses .

Chemicals stimulate the sensory cells in taste buds .

Chemical dissolve in saliva .

food


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Sense of

Hearing


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Sense of Hearing ( ear)Sense of hearing > ability of the ear to detect the stimulus of sound .

Sense of balancing > ability to detect changes of the position of the body .Mechanism of hearing >

Pinna

Auditory canal

Eardrum

Cochlea

Ossicles

Oval window

Auditory nerve

Brain


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Senseof

Sight


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Sense of sight ( eyes)The human eyeball > spherical in shapenand lies in the eye socket .

The movements of the eyeball > controlled by three pairs of extrinsic muscles .

The mechanism of sight >

Light

Cornea

Aqueous humour

Vitreous humour

Optic nerve

Retina

Brain

Lens

pupil


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Christina Perri A Thousand YearsHeartbeats fastColors and promisesHow to be braveHow can I love when Im afraid to fallBut watching you stand alone

All of my doubt suddenly goes away somehowOne step closer

I have died everyday waiting for youDarling dont be afraid I have loved youFor a thousand yearsIll love you for a thousand more

Time stands still

Beauty in all she isI will be braveI will not let anything take awayWhats standing in front of meEvery breathEvery hour has come to thisOne step closer

I have died everyday waiting for youDarling dont be afraid I have loved youFor a thousand yearsIll love you for a thousand more

And all along I believed that I would find youTime has brought your heart to meI have loved you for a thousand yearsIll love you for a thousand more

One step closerOne step closer

I have died everyday waiting for youDarling dont be afraid I have loved youFor a thousand years

Ill love you for a thousand more

And all along I believed I would find youTime has brought your heart to meI have loved you for a thousand yearsIll love you for a thousand more


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Plug In stereo Oh Darlingyou seem quite nice for a girl with good looks

And Im the kinda fellow thatll make you feel better when your life gets shook

So give it a chance according to your plans

I bet I'm not number one on your list to kiss, but please understand

You seem quite shy, but youre oh so cute

And Im the kind of girl that would love to be yours if you'd asked me to

So just take a chance, try to hold my hand

I swear Id never let go

Just let me know if youd be my man

I really want to come out and tell you

Oh darling, I love you so

If youd ask me for my heart, theres no way that Ill say no

Oh darling, just take a chance pleaseSo we can stay together till hell starts to freeze

You seem quite right for a boy like me

And I wanna know would you treat me well

Would you treat me like a queen

Cause Id like to show you and make you see

That although were different types

We were meant to be

I really want to come out and tell you



Oh darling, just take a chance please

So we can stay together till hell starts to freeze

So I gotta ask you,

I cant be afraid

I gotta take a chance at love

So what do you say



Oh darling, just take a chance pleaseSo we can stay together till hell starts to freeze



Oh darling, just take a chance please

So we can stay together till hell starts to freeze


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Light And SightLight travels in straight lines.

When light falls on dull surface, part of the light is absorbed and part of it

reflected.

Rate of reflection depends on > the colour of the surface

>the condition of the surface

Reflection of light can be used in the following

a) Periscope > a device that can be used to see over or around opaque object .It can be also used in submarines.

b) Kaleidoscope > a device that is able to produce beautiful and colourful imageswhen small objects are put into it .


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World Through Our Sense