Ch. 7.7 Special Senses Key Terms
1. 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.
10. Lacrimal Glands
Glands in the eye that produce tears, which constantly moisten and cleanse the eye.
18. Sclera
The outermost layer of the eye, made of tough connective tissue. It's often called the "white" of the eye and maintains the shape of the eye.
8. 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.
20. Tympanic Membrane
The eardrum. It separates the outer ear from the middle ear. It vibrates when sound waves hit it and transmits them to the middle ear's ossicles.
4. Choroid Coat
The middle layer of the eye, which is interlaced with many blood vessels that nourish the eyes.
11. Lens
A circular structure located behind the pupil that refracts (bends) light rays so the rays focus on the retina.
22. 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.
12. Organ of Corti
The receptor of sound waves, located inside the cochlea. It is composed of delicate, hairlike mechanoreceptor cells that transmit impulses to the auditory nerve.
21. Vestibule
The first section of the inner ear, separated from the middle ear by the oval window. It acts as the entrance to the cochlea and semicircular canals.
6. Conjunctiva
A mucous membrane that lines the eyelids and covers the front of the eye to provide additional protection and lubrication.
15. Pupil
The opening in the center of the iris; its size is controlled by the muscles of the iris to regulate light entry.
2. Auditory Canal
A canal or tube (external auditory meatus) that sound waves travel through from the pinna to the tympanic membrane (eardrum). It contains glands that produce cerumen (wax).
13. Ossicles
The three small bones in the middle ear: the malleus (hammer), incus (anvil), and stapes (stirrup). They connect and transmit sound waves from the tympanic membrane to the inner ear.
7. Cornea
A circular, transparent part of the front of the sclera. It allows light rays to enter the eye and helps to refract light.
16. Refracts
To bend light rays, a function performed by the cornea, aqueous humor, lens, and vitreous humor to focus the image on the retina.
3. Auricle
Also called the pinna, this is the visible, outer part of the ear made of elastic cartilage covered by skin. It collects sound waves.
14. Pinna
Also called the auricle, the visible, outer part of the ear that collects sound waves.
9. 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.
17. Retina
The innermost layer of the eye, made of many layers of nerve cells (including rods and cones) that transmit light impulses to the optic nerve. This is where the image focuses.
5. Cochlea
A structure in the inner ear, shaped like a snail's shell, that contains the organ of Corti (receptor of sound waves).
19. Semicircular Canals
Structures located in the inner ear that contain a liquid and hairlike cells. They send impulses to the cerebellum to help maintain our sense of balance and equilibrium.