Sensory Reception: Hearing & Vision

A collection of Q&A flashcards covering auditory and visual sensory reception, including ear anatomy, cochlear function, phototransduction, and pupil regulation.

What is the function of the pinna of the ear?

It acts as a funnel to direct sound waves into the auditory (ear) canal.

Which structure separates the external ear from the middle ear and vibrates in response to sound?

The tympanic membrane (eardrum).

Name the three auditory ossicles in order from the tympanic membrane to the inner ear.

Malleus, Incus, Stapes.

Onto which membrane does the stapes press to transmit vibrations into the cochlea?

The oval window.

Which fluid-filled chamber of the cochlea receives the initial pressure wave after the oval window is struck?

Scala vestibuli (filled with perilymph).

What is the fluid inside the scala media (cochlear duct) called, and which ion is it rich in?

Endolymph, rich in potassium (K⁺).

Which specialized sensory structure within the cochlear duct converts mechanical waves to electrical signals?

The organ of Corti.

How does bending of stereocilia depolarize hair cells in the cochlea?

Mechanically gated K⁺ channels open, letting potassium flow into the hair cells down its electrochemical gradient.

Through which cranial nerve is auditory information carried to the brain?

The vestibulocochlear nerve (Cranial Nerve VIII).

Define the term "endocochlear potential."

The large voltage difference (~–150 mV) between endolymph and hair-cell interior that makes the cells highly sensitive to sound.

What are the five special senses?

Taste, Hearing, Vision, Equilibrium, and Olfaction (smell).

Which two muscles control pupil diameter, and which division of the autonomic nervous system activates dilation?

Radial dilator muscle and circular sphincter (constrictor) muscle; sympathetic activation causes dilation.

Why do pupils constrict when a bright light is shone into the eye?

Contraction of the pupillary sphincter muscle limits light entry to protect retinal cells and optimize vision.

In what order do light rays encounter retinal cells on their way to the brain?

Ganglion cell → Bipolar cell → Photoreceptor (rods or cones).

What neurotransmitter is released by photoreceptors in the dark, and what effect does it have on bipolar cells?

Glutamate; it inhibits (hyperpolarizes) bipolar cells.

What happens to glutamate release from photoreceptors when they are exposed to light?

Glutamate release stops, relieving inhibition and allowing bipolar cells to depolarize.

Which cells generate action potentials that travel along the optic nerve?

Ganglion cells.

To which lobe of the brain does the optic nerve project visual information?

The occipital lobe.