Human Senses. Touch. Fingerprint. Vidhya Peetham i-school. The skin in our fingers is very sensitive. The skin in our back is not very sensitive.

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1 Vidhya Peetham i-schl Human Senses Humans have five senses. They are hearing, sight, smell, taste and tuch. Often, we use mre than ne sense at the same time. All the five senses wrk with the brain and help us knw abut the wrld arund us. Tuch Skin helps us feel the sense f tuch. It helps us feel pain, temperature and tuch. Skin is the largest rgan in the bdy. Sme parts f the bdy are mre sensitive than the thers. The skin in ur fingers is very sensitive. The skin in ur back is nt very sensitive. When the skin tuches smething, it sends a message t the brain thrugh the nerve. The brain helps us knw the sensatin. Fingerprint The skin n ur fingers frms patterns. These patterns are called fingerprints. Each persn s fingerprints are unique (it is different fr each persn). Even twins have different fingerprints. Types f fingerprint Fingerprints may have ne f these patterns. Page1

2 Sight Vidhya Peetham i-schl The eyes help us see. The fllwing are the parts f the eye. Pupil it is the black hle in the middle f the eye; light enters the eye thrugh the pupil Iris it is the clred part f the eye; it cntrls the pening f the pupil Eyelid prtects the eye Eyelash prtects the eye frm dust Eyebrw stps sweat frm entering the eye Hw We See Read the picture carefully t understand hw we see. Page2

3 Vidhya Peetham i-schl Optical Illusins Optical mean sight. Illusin means nt real. See the picture n the right. It seems t shake. Optical illusins happen because they send wrng infrmatin t the brain. Smell The nse helps us smell. Read the picture carefully t understand hw we smell. Page3

4 Vidhya Peetham i-schl Surce f Smell If the surce f smell is clse, we will get the smell fast. If the surce f smell is far, we will get the smell slwly. Strng Smell Sme things like perfumes have many small particles. These particles can travel far. That is why perfumes have a strng smell. Sme things d nt smell unless they are cut, rubbed r grund. Example: nin Hw Smelling Saves Us Smelling smke when smething is burning can save us frm fire. Bad smell f rtten fd stps us frm eating it. Page4

5 Vidhya Peetham i-schl Harmful Smells Sme materials cntain harmful chemicals. Example: petrl, paint etc. When we smell these materials, tiny particles frm them can enter the nse and lungs. This can make us sick. What Happens When We Breathe Air enters the nse. In the nse the dust in the air is remved by tiny nasal hairs and mucus (the sticky thing in the nse). Frm here the air enters the lungs. Taste The tngue helps us taste. It can identify five tastes. They are bitter, salty, sur, sweet and umami tastes. Different parts f the tngue identify different tastes. When we eat The chemicals in the fd trigger the sensrs in the taste buds. The taste buds send message thrugh nerves t the brain. The brain recgnizes the taste. Page5

6 Vidhya Peetham i-schl Saliva, Smell and Sight Help Us Taste Saliva is a wet liquid that is prduced in the muth. When we eat, chemicals in the fd mix with the saliva. Only when these tw mix, taste buds sense the fd. S, nly if the tngue is wet, we can taste well. If the tngue is dry, we cannt taste well. Difference Between Taste and Flavur The five tastes are bitter, salty, sur, sweet and umami tastes. Only the taste buds in the tngue are respnsible fr this. Fr flavur, the ther senses like smelling and seeing are needed. Sur Green Apple, Strawberry and Blue Raspberry are the flavurs f the pickles. Smell and flavur. When we eat, the smell chemicals in the fd drift t the smell sensrs in the nse. Frm there, messages g t the brain and flavur is recgnised. S, if the nse is clsed, we cannt get the flavur well. Sight and flavur. When we see the fd we eat, we can the flavur better. Page6

7 Hearing Vidhya Peetham i-schl The speaker prduces sund waves. These sund waves reach the uter ear. Then, they pass thrugh the ear canal. Here, the sund waves hit the ear drum and make it vibrate. These vibratins make the small bnes in the middle ear vibrate. These vibratins make the sensr hairs in the inner ear vibrate. Frm here, nerves take the message t the brain. The brain recgnizes the sund. Why We May Lse Our Hearing As we grw ld, the sensr hairs in the inner ear may get damaged. New sensr hairs d nt grw. S, many ld peple lse their hearing. Very lud nise can damage hearing. S, we must stay away frm lud nise. We can prtect ur ears by wearing ear muffs. The ears f children are mre sensitive t nise than adults. This is because children have shrter ear canals. Page7

8 Vidhya Peetham i-schl Tls t Imprve Hearing Sme peple cannt hear well. They wear hearing aids t hear better. They amplify (make luder) sunds. Befre hearing aids were invented, peple used ear trumpets t amplify sunds. The ear trumpets are bigger than the ears. S, mre sund waves are cllected and sent t the sensr hairs in the inner ear. Surce f Sund Anything that makes sund is a surce f sund. Sund will be lud if we are clse t the surce f sund. Sund will be sft if we are far frm the surce f sund. Page8