chapter 17 part3.5 p.578-581

Question 0

Around the edges of the lens, the elastic ________ of the lense intermingle with those of the ciliary zonule

Answer 0

capsular fibers

Question 1

what covers the entire lens?

Answer 1

dense fibrous capsule

Question 2

Cells in the interior of the lens are called

Answer 2

lens fibers

Question 3

lens fiber cells lost their nuclei + organelles - they are long+ slender and filled w/ transparent proteins called what

Answer 3

crystallins

Question 4

abnormality characterized by lens losing its transparency

Answer 4

cataract

Question 5

4 possible causes of cataract

Answer 5

1. injuries
2. radiation
3. reaction to drug
4. senile cataract

Question 6

in human eyes, greatest amount of refraction occurs when light passes into

Answer 6

cornea

Question 7

cornea has density close to

Answer 7

water

Question 8

Less significant but also a contributor to light refraction in human eyes is

Answer 8

lens from aqueous humor

Question 9

focal distance of lens

Answer 9

sitance between center of the lens and focal point of the lens

Question 10

2 factors that determine focal distance

Answer 10

1. distance of object from lens- closer the object, the greater the focal distance
2. shape of the lens- rounder lens show more refraction- very round lens- shorter focal distance

Question 11

automatic adjustment of eye to give clear vision

Answer 11

acommondation

Question 12

Lens is held in place by ______ that originates at ______

Answer 12

ciliary zonule, ciliary body

Question 13

smooth muscle fiber in the ciliary body act like ______ muscle

Answer 13

sphincter

Question 14

When the ciliary muscle contracts, the ciliary body moves________
what happens to the lens

Answer 14

toward the lens, reducing the tension in the ciliary zonule

The elastic capsule pulls the lens into rounder shape that increases its refraction power

Question 15

inner limit of clear vision called what + determined by

Answer 15

near point of vision, elasticity in the lens

Question 16

astigmatism

Answer 16

degree of curvature in the cornea or lens varies from one axis to another

Question 17

The image projected on the retina is

Answer 17

upside down, smaller and reversed left/right

Question 18

legally blind visual acuity

Answer 18

below 20/200

Question 19

scotoma

Answer 19

abnormal blind spot

Question 20

3 possible causes of scotoma

Answer 20

1. compression of optic nerve
2. damage to photoreceptors
3. central damage along visual pathway

Question 21

floaters + cause

Answer 21

small spots that drift across field of vision

blood cells, cellular debris in vitreous body