Siddiqui Tutor

 Sense  Organs 

 The world around us is very interesting. Allah Almighty has blessed us with five sense organs to enjoy the world. Sense organs are special parts of our body that tell us what is going on around us. Our eyes, ears, skin, nose, and tongue are our sense organs. All the sense organs are linked to the brain by nerves.

The Eye

We see with our eyes. Our eyes tell us about the colors, shapes, and movements of objects around us. The eye is an organ of sight. The human eye consists of an eyeball. The eye is covered with eyelids. Eyelashes on the eyelids keep away dust particles. Under the upper eyelids tear glands open.

The main parts of our eye are the cornea, iris, pupil, lens, retina, and optic nerve.

Cornea

In the front of eye, the transparent part is called cornea. Light rays enter the eye through the cornea.

Iris

Beneath the cornea the coloured portion of the eye is called iris. Have you ever observed brown, blue and hazel eyes of your friends?

There is a hole in the middle of the iris, known as pupil. This pupil contracts in bright daylight and expands in dim light.

Lens

Behind the pupil, a flexible lens is present. The lens helps the eye to focus light.

Retina

The light sensitive portion of the eyeball is called retina. Eye lens forms the image on the retina.

Optic nerve

When light hits the retina, its cells make nerve signals. These signals pass along the optic nerve to the brain.

The Ear

We hear sounds through our ears. Ear is an organ of hearing. Human ear consists of three parts; outer ear, middle ear and inner ear.

Outer Ear

The outer ear consists of a pinna and a long narrow tube called ear canal. The pinna collects sound waves from the air around. The sound waves then travel along the ear canal.

Middle Ear

The outer ear is connected to the middle ear by a thin membrane called the ear drum. The eardrum vibrates when sound waves strike it. On the other side of the ear drum is the middle ear which is filled with air. It has three small bones in the body, i.e. hammer, anvil and stirrup.

Inner Ear

The last part of the ear is the inner ear. The inner ear is filled with a liquid. This part of ear has a coiled structure called cochlea. The cochlea is the actual hearing organ. The cochlea sends signals to the brain through a special nerve called auditory nerve.

The Skin

The largest sense organ in our body is the skin. Skin is the organ of touch. Skin covers every part of our body. It protects the inner parts of our body. The skin contains several kinds of cells that detect pain, pressure, touch, heat and cold.

Our skin has an outer layer and an inner layer. The outer layer has colour pigment and protects the skin from harmful rays of the Sun. The inner layer has blood vessels, nerves, sweat glands and roots of hairs. This layer is the sensitive part of the skin. When we touch something, sensitive cells of the skin receive

messages and send them to the brain.

The Nose

Suppose there is a dead and decaying rat in one of your room's corners. How would you come to know about the dead rat? Of course, you would smell bad odour in the room. The sense organ for smelling is the nose.

Our nose is a hollow air passage. It has two openings called nostrils. In each side of the nose is an air chamber. The roof of the nose has lining of nerve cells to sense smell. When certain odour chemicals present in air enter our nose, they touch the nerve cells. Nerve cells pass the message to the brain through the olfactory nerve. Our brain tells whether the odour is pleasant or unpleasant.

The Tongue

Our tongue is the sense organ of taste. It helps to detect the flavour of food. We can detect sweet, salty, sour and bitter tastes with our tongue.

The upper surface of the tongue is covered with many pimple like lumps. Between these lumps, taste buds are present. Each taste bud has many nerve cells. When particles of a food touch the taste buds, nerves send signals of taste to the brain.

We feel sweet, salty, sour and bitter tastes on different parts of our tongue. The tip of the tongue has taste buds to detect sweet taste. The sides of the tongue are sensitive to salty and sour tastes. The back of the tongue has taste buds to detect bitter taste.