Ch. 7.7 Key Terms
Aqueous Humor
A clear, watery fluid that fills the space between the cornea and the iris. It helps maintain the forward curvature of the eyeball and refracts light rays.
Auditory Canal
The canal, or tube, that leads inward from the pinna/auricle to the tympanic membrane.
Auricle
The visible, external part of the ear, also called the pinna.
Choroid Coat
The middle layer of the eye that is interlaced with many blood vessels that nourish the eyes.
Cochlea
: A spiral-shaped structure in the inner ear that contains the organ of Corti, the receptor of sound waves.
Cornea
: A circular, transparent part of the front of the sclera. It allows light rays to enter the eye.
Pupil
: The opening in the center of the iris through which light passes.
Vestibule
: The first section of the inner ear that acts as the entrance to the cochlea and semicircular canals.
Retina
: The innermost layer of the eye, made of many layers of nerve cells that transmit light impulses to the optic nerve.
Refracts
: The act of causing light rays to bend as they pass through parts of the eye (like the cornea, aqueous humor, lens, and vitreous humor) so they focus on the retina.
Sclera
: The outermost layer of the eye, a tough connective tissue frequently called the "white" of the eye. It maintains the shape of the eye.
Tympanic Membrane
: The eardrum. It separates the outer ear from the middle ear and vibrates when struck by sound waves.
Pinna
: The visible, external part of the ear, also called the auricle.
Lacrimal Glands
: Glands in the eye that produce tears, which constantly moisten and cleanse the eye.
Ossicles
Three small bones (malleus, incus, and stapes) in the middle ear that transmit sound waves from the tympanic membrane to the inner ear.
Iris
: The colored portion of the eye, located behind the cornea. It contains muscles that control the size of the pupil and regulate the amount of light entering the eye.
Lens
: A circular structure located behind the pupil. It refracts (bends) light rays so the rays focus on the retina.
Eustachian Tube
A tube that connects the middle ear to the pharynx (throat). It allows air to enter and helps equalize air pressure on both sides of the tympanic membrane.
Organ of Corti
: The specialized structure within the cochlea containing hairlike mechanoreceptor cells; it is the receptor of sound waves.
Semicircular Canals
: Canals located in the inner ear that contain liquid and hairlike cells. They help to maintain our sense of balance and equilibrium.
Vitreous Humor
: The jellylike substance that fills the area behind the lens. It helps maintain the shape of the eyeball and also refracts light rays.
Conjunctiva
A mucous membrane that lines the eyelids and covers the front of the eye to provide additional protection and lubrication.