Overview of the Senses -- SIGHT -- Retina

Question 1

-Contains epithelia, neurons, and nerve fibers for sight

Answer 1

Retina

Question 2

Made of epithelium filled with proteins called crystallines

Answer 2

Lens

Question 3

Mucous membrane that covers cornea and lines eyelids

Answer 3

Conjunctiva

Question 4

Clear gel-like substance that supports eye shape; Holds retina firmly against choroid

Answer 4

Vitreous humor

Question 5

Distance it takes for light rays to converge on the fovea after passing through the cornea. Typically 22 mm for average eye.

Answer 5

FOCAL DISTANCE:

Question 6

Any change in the _______ _______ results in blurry
vision

Answer 6

focal distance

Question 7

What are the 4 Focusing of Images on the Retina?

Answer 7

Light Refraction

Convergence-

Far Vision

Near Vision i

Question 8

Light rays are bent (refracted) as they enter the eye
which directs/aims them toward a small area of the retina called the fovea.

Answer 8

Light Refraction

Question 9

The cornea has more refractive power than the lens—making it most important in focusing

Answer 9

Light Refraction

Question 10

Light rays come together/merge (converge) into a point directly on the fovea.

Answer 10

Convergence-

Question 11

The fovea produces the sharpest image because it contains the largest number of cones

(photoreceptor neurons) in the retina.

Answer 11

Convergence-

Question 12

The fovea is surrounded by the

________ _________ (yellow spot).

Answer 12

macula
lutea

Question 13

Refraction & Conversion occur easily when focusing on a distant object.

Answer 13

Far Vision

Question 14

The eye is relaxed. The suspensory ligaments maintain pressure on the lens, keeping it relatively _______\_.

Answer 14

flat

Question 15

involves accommodation

Answer 15

Near Vision

Question 16

Two major structural problems alter focal
distance:

Answer 16

1. Eyeball length (too short /too long)
2. Abnormal cornea shape - too round or too flat

Question 17

Ciliary muscles contract, lens becomes more round (increased curvature), allowing better refraction & convergence of the light rays so that the image falls onto the fovea.

Answer 17

Near Vision

Question 18

The pupil also constricts.

Answer 18

Near Vision i

Question 19

If the cornea is perfect the focal didtance would be………

Answer 19

22 mm

Question 20

Near Vision involves accommodation it starts at about?

Answer 20

6m/20ft