Chap 17, The Eye, Vocabulary

Question 1

accommodation

Answer 1

Normal adjustment of the eye to focus on objects from far to near. The ciliary body adjusts the lens (rounding it) and the pupil constricts. When the eye focuses from near to far, the ciliary body flattens the lens and the pupil dilates.

Question 2

anterior chamber

Answer 2

Area behind the cornea and in front of the lens and iris. It contains aqueous humor.

Question 3

aqueous humor

Answer 3

Fluid produced by the ciliary body and found in the anterior chamber. A humor is any body fluid, including blood and lymph.

Question 4

biconvex

Answer 4

Consisting of two surfaces that are rounded, elevated, and curved evenly, like part of a sphere. The lens of the eye is a biconvex body.

Question 5

choroid

Answer 5

Middle, vascular layer of the eye, between the retina and the sclera.

Question 6

ciliary body

Answer 6

Structure surrounding the lens that connects the choroid and iris. It contains ciliary muscles, which control the shape of the lens, and it secretes aqueous humor.

Question 7

cone

Answer 7

Photoreceptor cell in the retina that transforms light energy into a nerve impulse. Cones are responsible for color and central vision.

Question 8

conjunctiva

Answer 8

Delicate membrane lining the undersurface of the eyelids and covering the anterior eyeball.

Question 9

cornea

Answer 9

Fibrous transparent layer of clear tissue that extends over the anterior portion of the eyeball.

Question 10

fovea centralis

Answer 10

Tiny pit or depression in the retina that is the region of clearest vision.

Question 11

fundus of the eye

Answer 11

Large posterior, inner part of the eye that is visualized with an ophthalmoscope.

Question 12

iris

Answer 12

Pigmented (colored) layer that opens and closes to allow more or less light into the eye. The central opening of the iris is the pupil.

Question 13

lens

Answer 13

Transparent, biconvex body behind the pupil of the eye. It bends (refracts) light rays to ring them into focus on the retina.

Question 14

macula

Answer 14

Yellowish region on the retina lateral to and slightly below the optic disc; contains the fovea centralis, which is the area of clearest vision.

Question 15

optic chiasm

Answer 15

Point at which optic nerve fibers cross in the brain.

Question 16

optic disc

Answer 16

Region of the back of the eye where the optic nerve meets the retina. It is the blind spot of the eye because it contains only nerve fibers, no rods or cones, and is thus insensitive to light.

Question 17

optic nerve

Answer 17

Cranial nerve carrying impulses from the retina to the brain (cerebral cortex).

Question 18

pupil

Answer 18

Central opening of the eye, surrounded by the iris, through which light rays pass. It appears dark.

Question 19

refraction

Answer 19

Bending of light rays by the cornea, lens, and fluids of the eye to bring the rays into focus on the retina. Refract means to break (-fract) back (re-).

Question 20

retina

Answer 20

Light-sensitive nerve cell layer of the eye containing photoreceptor cells (rods and cones).

Question 21

rod

Answer 21

Photoreceptor cell of the retina essential for vision in dim light and for peripheral vision.

Question 22

sclera

Answer 22

Tough, white outer coat of the eyeball.

Question 23

thalamus

Answer 23

Relay center of the brain. Optic nerve fibers pass through the thalamus on their way to the cerebral cortex.

Question 24

vitreous humor

Answer 24

Soft, jelly-like material behind the lens in the vitreous chamber; helps maintain the shape of the eyeball.

Question 25

uvea

Answer 25

The choroid, iris and ciliary body are known as the uvea of the eye.