Ch. 7.7 Special Senses Key Terms
1. Aqueous humor
A watery fluid that fills the space between the cornea and the lens. It helps maintain the shape of the eyeball and also refracts light rays.
10. Lacrimal glands
Located above the outer corner of the eye. They produce tears which constantly moisten and cleanse the eye.
Sclera
The outermost layer of the eye; a tough connective tissue often referred to as the "white" of the eye. It helps maintain the shape of the eye.
Eustachian tube
A tube that connects the middle ear to the pharynx. This tube allows air to enter the middle ear and helps equalize air pressure on both sides of the tympanic membrane.
Tympanic membrane
The membrane that separates the external auditory canal from the middle ear. It is commonly called the eardrum. It vibrates when sound waves hit it and transmits the sound wave to the middle ear.
4. Choroid coat
The middle layer of the eye, located beneath the sclera. It is interlaced with many blood vessels that nourish the eye.
Pupil
An opening in the center of the iris whose size is controlled by the iris muscles to regulate light entry.
Vitreous humor
A jellylike substance that fills the area behind the lens. It helps maintain the shape of the eyeball and also refracts light rays.
Organ of Corti
The structure located in the cochlea that contains the hairlike receptor cells for hearing.
Vestibule
The entrance to the two other parts of the inner ear (cochlea and semicircular canals), located between the middle ear and the inner ear.
6. Conjunctiva
A mucous membrane that lines the inner surfaces of the eyelids and covers the front of the eyeball.
Lens
A circular structure located behind the pupil and suspended in position by ligaments. It refracts (bends) light rays so the rays focus on the retina.
Auditory canal
A canal that extends from the pinna to the tympanic membrane. Sound waves travel through it. Also called the external auditory meatus.
Ossicles
Three small bones in the middle ear (the malleus, the incus, and the stapes) that connect to and transmit sound waves from the tympanic membrane to the inner ear.
Refracts
The action of the cornea, aqueous humor, lens, and vitreous humor as they bend light rays to focus the image on the retina.
Cornea
A circular, transparent part of the front of the sclera. It allows light rays to enter the eye.
Refracts
The action of the cornea, aqueous humor, lens, and vitreous humor as they bend light rays to focus the image on the retina.
Auricle
Another term for the pinna (the visible part of the ear).
Pinna
The visible part of the ear, which is made of cartilage. It is also called the auricle.
Lens
A circular structure located behind the pupil and suspended in position by ligaments. It refracts (bends) light rays so the rays focus on the retina.
Iris
The colored portion of the eye, located behind the cornea in front of the choroid coat. It contains two muscles, which control the size of the pupil and regulate the amount of light entering the eye.
Retina
The innermost layer of the eye, located on the back surface of the eyeball. It contains the light receptor cells: rods (for dim light and peripheral vision) and cones (for color and central vision).
Cochlea
A snail-shaped, shell-like structure in the inner ear. It contains the organ of Corti and is where sound waves are converted into nerve impulses.
Semicircular canals
Three small canals located in the inner ear. They contain liquid and hairlike cells that bend when the liquid moves, and their impulses travel to the cerebellum to help maintain the sense of balance and equilibrium.
Vitreous humor
A jellylike substance that fills the area behind the lens. It helps maintain the shape of the eyeball and also refracts light rays.