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