Question

Give the function of the following structures:
(i) Ear pinna
(ii) External auditory meatus
(iii) Cochlea
(iv) Semicircular canals
(v) Lachrymal gland
(vi) Eyelids
(vii) Retina
(viii) Eye lens
(ix) Pupil
(x) Olfactory lobe
(xi) Optic lobe
(xii) Medulla oblongata

Answer 1

(i) The function of the ear ​pinna is to collect sound waves and pass them on to an S-shaped tube called the external auditory canal.

(ii) The external auditory meatus is the canal in the ear that serves as a passageway from the outer ear to the ear drum.

(iii) The cochlea is a spiral canal 35 mm long and is a part of the inner ear. Here, sound waves are converted into electrical impulses. These electric impulses are then carried on to the brain, which helps us to hear sounds.

(iv) The main function of the semi-circular canals is to maintain the balance of the body.

(v) The lachrymal gland secretes tears onto the surface of the eyeball. Tears moisten, lubricate and clean the surface of the eye.

(vi) The eyelid covers and protects the eye from dust and other foreign objects.

(vii) The retina is the 'film' of the eye, if we compare the eye to a camera. The retina is the light-sensing part of the eye. It converts the incident light into electrical signals and sends them to the brain.

(viii) The eye lens focusses light rays on the light-sensitive screen called the retina.

(ix) The pupil controls the amount of light entering our eyes.

(x) The olfactory lobe helps us to get the sense of smell.

(xi) The optic lobe helps in visual perception and colour recognition.

(xii) The major function of the medulla oblongata is to control autonomic functions (that are not in human control), such as breathing, respiration and heartbeat. It is also involved in body secretions, reflexes and the actions of swallowing, coughing and sneezing.