Question

The middle ear converts

(A) air pressure waves to fluid pressure waves.

(B) air pressure waves to nerve impulses.

(C) fluid pressure waves to nerve impulses.

(D) pressure waves to hair cell movements.

Short answer

1. The option “air pressure waves to fluid pressure waves” istrue.

2. The option “air pressure waves to nerve impulses” isfalse.

3. The option “fluid pressure waves to nerve impulses” is false.

4. The option “pressure waves to hair cell movements” is false.

Step-by-step solution

Ear

The structure of an ear consists of three parts: the outer, middle, and inner ear. The tympanic membrane separates the outer and middle ear. The middle ear transmits sound collected by the outer ear to the inner ear.

Explanation of option ‘(A)’

The middle ear consists of three ossicles- malleus (hammer), incus (anvil), and stapes (stirrup). As vibrations from the eardrum travel through the middle ear, the ossicles get set into motion. The stapes vibrate against the oval window, a membrane on the cochlea’s surface creating pressure waves in the cochlear fluid.

Thus, the stapes of the middle ear aids in the conversion of air pressure waves to fluid pressure waves.

Therefore, the given statement is true.

Explanation of option ‘(B)’

Perception of sound occurs as sound or pressure waves in the air get converted into a nerve signal. Air pressure waves undergo conversion to fluid pressure waves in the middle ear. Then conversion of fluid pressure into nerve impulses takes place in the inner ear.

Thus, direct conversion of air pressure waves to nerve impulses does not occur but via fluid pressure conversion.

Therefore, the given statement is false.

Explanation of option ‘(C)’

The vibrations in the fluid cause hair cell movements in cochlear fluid. The movement of hair cells produces nerve impulses. Therefore, the cochlea converts sound or fluid pressure waves into nerve impulses.

Thus, the conversion of fluid pressure waves to nerve impulses occurs in the cochlea, a part of the inner ear.

Therefore, the given statement is false.

Explanation of option ‘(D)’

Hair cells are mechanoreceptors attached to the tectorial membrane in the inner ear that detect motion. As sound waves travel, the basilar membrane in the inner ear vibrates. Such vibration causes movement and depolarization of hair cells.

Thus, the pressure waves causing hair cell movements occur in the inner ear.

Therefore, the given statement is false.