(a) Sense of touch is due to touch corpuscles in the skin.
(b) Sense of taste is due to taste buds in the papillae of the tongue. Tip of the tongue is most sensitive to sweet taste, and the back part is sensitive to bitter taste.
(c) Sense of sight: To see an object, its image must be formed on the retina. Convexity of the lens of the eye increases when the object is nearer and it decreases when the object is far away to get the image in each case on the retina. The property of the lens by which it is able to adjust its convexity to form distinct image of the object at various distances from it on the retina is called accommodation. When ciliary muscles do not work properly to bring about accommodation of the lens, the eye becomes defective.”
Image Source: upload.wikimedia.org
(i) Myopia (or short-sightedness):
ADVERTISEMENTS:
When a person can see nearer objects distinctly but not distant ones, he is said to be suffering from myopia. In this case the convexity of the lens of his eye cannot be sufficiently decreased to form the image of the distant object on the retina. It is remedied by the use of concave glasses.
(ii) Hypermetropia (or long-sightedness):
When a person can see distant objects clearly but not the nearer he is said to be suffering from hypermetropia. It is remedied by the use of convex glasses.
(iii) Astigmatism:
The person can see vertical lines clearly but not the horizontal ones, or vice versa. It is remedied by the use of cylindrical glasses.
(iv) Colour blindness:
ADVERTISEMENTS:
If a person cannot distinguish between different colours (especially between red and green), he is said to be suffering from this defect.
(d) Sense of smell:
This is due to the presence of smell perceiving cells present in the lining of the nasal chambers.”
(e) Sense of hearing:
It is due to the movement of ear drum by the sound waves.