Chapter 9 - The eye Flashcards
1
Q
What wavelengths of light can the human eye see?
A
400-700 nm
2
Q
What are the pupil, the iris, the cornea, the sclera, and extraocular muscles?
A
- Pupil: Opening that allows light to enter the eye, black due to light-absorbing pigments in the retina
- Iris: Surrounding the iris, contains two muscles that vary the size of the pupil
- Cornea: Glassy transparent external sufrace of the eye; covers pupil+iris
- Sclera: “White of the eye”, tough wall of the eyeball
3
Q
What are extraocular muscles, the conjunctiva, and the optic nerve?
A
- Extraocular muscles: In the sclera, three pairs of muscles that move the eyeball in the orbit
- Conjunctiva: A membrane that folds back from the inside of the eyelids and attaches to the sclera
- Optic nerve: Carrying axons from the retina, exits the back of the eye, passes through the orbit, and reaches the base of the brain near the pituitary gland
4
Q
What are the optic disk, the macula, and the fovea?
A
- Optic disk: Blind spot, where the retinal blood vessels originate. No sensation of light; no photoreceptors.
- Macula: Part of the retina for central vision. No large blood vessels; improved quality of central vision.
- Fovea: Dark spot about 2mm in diameter, retina is thinner here than elsewhere.
5
Q
What are the aqueous humor, the lens, the ciliary muscle, and vitreous humor?
A
- Aqueous humor: Fluid behind the cornea that nourishes it.
- Lens: Transparent section located behind the iris.
- Ciliary muscle: Muscle that forms a ring inside the eye; lens suspended by ligaments attached to this.
- Vitreous humor: Viscous, jelly-like humor that lies between the lens and the retina; serves to keep the eyeball spherical.
6
Q
How does the eye form images?
A
By collecting light rays emitted by or reflected off objects in the environment, and focusing them onto the retina to form images.
The cornea is the site of most of the refractive power of the eyes; light reaches the eye from air and the cornea is mostly made of water.
