Question

Observe the illustration and answer the following questions.

(a) Identify the parts labelled as `X' and `Y'.
(b) What will be the effect of the rotational movement of head in `X'?
(c) Write the processes in `Y' that leads to hearing.

Hint:

Remember: Semicircular canals help in balance during movement, while cochlea converts sound vibrations into nerve impulses for hearing.

Answer 1

Step 1: Identify the labelled parts.
In the given figure of the inner ear, the part labelled `X' is the semicircular canals and the part labelled `Y' is the cochlea.
Step 2: Explain the function of `X'.
The semicircular canals are concerned with maintaining body balance, especially during rotational or angular movements of the head. They contain fluid and sensory hair cells that detect changes in the position and movement of the head.
Step 3: State the effect of rotational movement of head in `X'.
When the head rotates, the fluid inside the semicircular canals moves. This movement bends the sensory hair cells, generating nerve impulses which are sent to the brain. As a result, the brain gets information about the direction and speed of rotation, helping to maintain dynamic balance.
Step 4: Explain the role of `Y' in hearing.
The cochlea is the hearing part of the inner ear. Sound vibrations reaching the inner ear create waves in the fluid of the cochlea. These waves stimulate the sensory hair cells present in the organ of Corti.
Step 5: Describe the process leading to hearing.
The stimulated hair cells convert sound vibrations into electrical nerve impulses. These impulses are then carried by the auditory nerve to the brain, where they are interpreted as sound. Thus, the cochlea helps in the process of hearing.