Ch. 7.7 Special Senses Key Terms
1. Aqueous humor
A clear, watery fluid located between the cornea and iris; it maintains the forward curvature of the eyeball and refracts light rays.
Auditory canal
A canal or tube in the outer ear that carries sound waves inward; it contains glands that produce cerumen (earwax) to protect the ear.
Auricle (Pinna)
The visible, outer part of the ear made of elastic cartilage; it collects sound waves and directs them into the auditory canal.
Choroid coat
The middle layer of the eye, filled with blood vessels that nourish the eye.
Cochlea
A snail-shaped structure in the inner ear that contains the organ of Corti, which converts sound waves into nerve impulses.
Conjunctiva
A mucous membrane that lines the eyelids and covers the front of the eye, providing lubrication and protection.
Cornea
The transparent, curved front part of the sclera that allows light rays to enter the eye.
Eustachian tube
A tube connecting the middle ear to the throat; it equalizes air pressure on both sides of the tympanic membrane.
Iris
The colored part of the eye containing muscles that control the size of the pupil and regulate the amount of light entering the eye.
Lacrimal glands
Glands that produce tears to moisten and cleanse the eye; tears drain into the nasal cavity through the nasolacrimal duct.
. Lens
A circular structure behind the pupil that refracts (bends) light rays to focus them on the retina.
Organ of Corti
The receptor for sound in the cochlea; contains hairlike mechanoreceptor cells that convert sound waves into nerve impulses.
Ossicles
Three tiny bones in the middle ear—malleus, incus, stapes—that transmit sound waves from the eardrum to the inner ear.
Pinna
Same as auricle: the outer, visible part of the ear that funnels sound into the auditory canal.
Pupil
The black, round opening in the center of the iris where light enters the eye.
Refracts
Means to bend light rays so they focus properly on the retina.
Retina
The innermost layer of the eye containing rods and cones that convert light rays into nerve impulses sent to the optic nerve.
Sclera
The outer, tough white layer of the eye that maintains its shape and provides attachment for eye muscles.
Semicircular canals
Three fluid-filled structures in the inner ear that contain hair cells; they help maintain balance and equilibrium.
Tympanic membrane
The eardrum; it vibrates when sound waves strike it and transmits those vibrations to the ossicles.
Vestibule
The first section of the inner ear, located after the oval window; it serves as the entrance to the cochlea and semicircular canals and helps with balance.
Vitreous humor
A jellylike substance behind the lens that maintains the shape of the eyeball and refracts light rays.