sense organ

Question 1

names some receptors

Answer 1

• photoreceptors
• chemoreceptors
• thermoreceptors
• mechanoreceptors
• exteroceptors
• interceptors

Question 2

function of the eyelids?

Answer 2

control the amount of light entering the eye

Question 3

function of the eyelashes?

Answer 3

protection form entering dust particles

Question 4

what is the conjuctiva?

Answer 4

• thin transparent membrane covering the exposed part of the eye
• lubricated by tears

Question 5

what happens to extra tears?

Answer 5

• drains down into the nasolacrimal duct

Question 6

where is the eyeball locates?

Answer 6

in a socket (orbit) present in the skull held by 6 extrinsic muscles

Question 7

what are the layers that make up the walls of the eye?

Answer 7

-sclera
- choroid
- retina

Question 8

what is the sclera?

Answer 8

• tough, fibrous, white layer
• forms a transparent bulge at the front of the eye called the cornea
• denser medium than air causing light rays to refract upon entering

Question 9

what is the choroid?

Answer 9

-network of blood capillaries
- pigmented black (no internal reflection)
- froms ciliary body and iris

Question 10

what is the ciliary body?

Answer 10

contains ciliary muscles which alters the thickness of the lens

Question 10

what is the retina?

Answer 10

• photoreceptors
• images formed on the retina
• nerve ending to the optic nerve sending impulses to the brain
• two types of photoreceptors

Question 11

what is the iris?

Answer 11

disc shaped structure with a round hole (pupil) in the center

Question 12

what are the types of photoreceptors in the eye?

Answer 12

rods and cones

Question 13

what is the function of the optic nerve?

Answer 13

sending impulses to the brain once photoreceptors are stimulated

Question 14

amount of rods in the retina?

Answer 14

120 million

Question 15

what are the rods used for?

Answer 15

night/scotopic vision

Question 16

name of the pigment used for night vision?

Answer 16

vision purple

Question 17

where is vision purple located?

Answer 17

in the rods

Question 18

what happens to vision purple when it comes in contact with light?

Answer 18

it gets bleached

Question 19

function of the cones?

Answer 19

responsible for light vision (color vision)

Question 20

what are the types of cones?

Answer 20

red, blue and green

Question 21

amount of cones in the retina?

Answer 21

5 million

Question 22

what is the fovea?

Answer 22

point in the retina where visual activity is the highest

Question 23

how many cones are present in the fovea?

Answer 23

2000

Question 24

how does light enter the eye?

Answer 24

through the pupil

Question 25

what is the role of the ciliary body?

Answer 25

focusing and accommodation

Question 26

what is the function of the lens?

Answer 26

transmit light, focusing it on the retina

Question 27

what are the chambers of the eyeball?

Answer 27

2 chambers
- small one known as aqueous humor filled with a watery liquid
- large one has a jelly like fluid called vitreous humor
keep the eyeball firm

Question 28

describe the lens

Answer 28

transparent, biconvex and crystalline

Question 29

which vitamin assists in the formation of vision purple?

Answer 29

vitamin A

Question 30

what does the deficiency of vitamin A cause?

Answer 30

night blindness

Question 31

which photoreceptor absorbs light of diff wavelenghts?

Answer 31

cones, which enables us to see diff colours and a complete spectrum

Question 32

what is the yellow spot (fovea centralis)?

Answer 32

a shallow, yellow depression located in line with or on the optical axis of the lens

Question 33

what is the blind spot?

Answer 33

over the optic nerve where it enters the eye/ no photoreceptors found here

Question 34

what is the position of the ciliary body when seeing a distant object?

Answer 34

ciliary muscles relaxed
suspensory ligaments tightened
lens pulled thin

Question 35

what is the position of the ciliary body when seeing a close object?

Answer 35

ciliary muscles tightened
suspensory ligaments slackened
lens allowed to bulge