Question

The basilar membrane of the cochlea
A. Is unaffected by movement of fluid in the scala vestibule
B. Covers the oval window and round window
C. Vibrates in a pattern determined by the form of the travelling wave in the fluids of the cochlea
D. Vibrates when body is subjected to linear acceleration

Answer 1

Hint: Most of the animal has organ system organization in which cells coordinate to form tissues and tissue coordinate further to form the organs. These organs are in coordination with each other to perform different functions of the body. This coordination and integration of the organs is required to maintain a physiological balance called Homeostasis.

Complete answer:
Ears play an important role in control and coordination of the body. Humans have one pair of ears. Along with the hearing functions it also maintains the equilibrium of the body.
Ear mainly consists of three parts:
External Ear: The external ear is further divided into the following parts:
> Auricle (Pinna): It comprises a thin plate of elastic cartilage covered by a layer of skin. It is made up of funnel-like curves that collect sound waves and transmit them to the middle ear. Adipose and fibrous tissues of lobule supplied with blood capillaries.
> External Auditory Meatus: It is a little curved canal supported by bone in its interior part and cartilage in the exterior part. The meatus is lined with stratified epithelium and wax glands.
> Tympanic Membrane: Help in the separation of the middle ear and the external ear. Also receives and amplifies the sound waves.

Middle Ear
The middle ear comprises the following parts:
> Tympanic Cavity: It is a narrow air-filled cavity separated from the external ear and from inner ear by tympanic membrane and the bony wall respectively. It has an auditory tube known as the Eustachian tube in its anterior wall.
> Eustachian Tube: Equalizes air pressure on either side of the tympanic membrane and a 4cm long tube also connects the tympanic cavity with the nasopharynx.
> Ear Ossicles: they perform the transmission of sound waves from the eardrum to the middle ear.

Inner Ear: It comprises two parts:
> Bony labyrinth: It comprises a vestibule, three semicircular canals, and spirally coiled cochlea. It is filled with perilymph.
> Membranous labyrinth: It is surrounded by bony labyrinths. It consists of sensory receptors responsible for balance and hearing. This is filled with endolymph and comprises 3 semicircular ducts, cochlear duct, saccule and utricle.
> Basilar membrane is present in the inner ear which also contains a vestibular apparatus that senses the linear acceleration of the body with the help of utricle and saccule. This leads to movement in cochlear fluid due to which basilar membrane vibrates. Basilar membranes also have sensitivity to sound waves due to sensory receptor hair cells.

Cochlea is a hollow, spiral-shaped bone found in the inner ear, playing an important role in the sense of hearing and participates in the process of auditory transduction. Sound waves are transduced into electrical impulses which can be interpreted by the brain as individual frequencies of sound. The spiral shape of cochlea allows differing frequencies to stimulate specific areas along it which results in a tonotopic map that enables people to perceive various frequencies of sound. Specific areas along the cochlea are stimulated by vibrations carried within a fluid known as endolymph that is found in the cochlear duct. The vibrations are then converted to electrical impulses within the cochlear duct through mechanical stimulation of hair cells within a special structure referred to as the organ of Corti. These nerve impulses are carried by the auditory nerve from the cochlea to the brain for interpretation.

So, the correct answer is D, vibrates when the body is subjected to linear acceleration.

Note: The hardest bone temporal bone is also present in the ear which helps in the protection of the ear. Ear also consist of the smallest bone of the body- stapes or stirrup bone. Ear produce wax as a natural protective agent.