Sub-Module for Coordination and Control: Sense Organs (the eyes)

Question 1

list the 9 parts of the external structure of the eye

Answer 1

1. eyelashes
2. eyelids
3. eyebrows
4. tear duct
5. sclera
6. conjunctiva
7. iris
8. pupil
9. tear gland

Question 2

state the functions of the eyelashes, eyelids, and eyebrows

Answer 2

• eyelashes: prevents dust from entering the eye
• eyelids: protects the eyes from damage and the retina from bright light
• eyebrows: prevents sweat from entering the eye

Question 3

state the functions of the tear ducts and tear glands.

Answer 3

• tear ducts: drains excess tears from your eye into your nasal cavity
• tear glands: secretes tears to cleanse and lubricate the eye

Question 4

state the functions of the sclera and conjunctiva

Answer 4

• sclera: it is a protective tough white layer of the eye that protects the structure of the eye
• conjunctiva: the thin transparent layer that present dusts from entering the eye

Question 5

state the functions of the iris and pupil

Answer 5

• iris: it has coloured muscles that control the amount of light entering the eye
• pupil: it works along with the iris to regulate the amount of light entering the eye

Question 6

list the 8 parts of the internal structure of the eye

Answer 6

1. cornea
2. retina
3. lens
4. choroid
5. fova/yellow spot
6. blind spot
7. optic nerve
8. cillary muscles

Question 7

state the functions of the cornea and the lens

Answer 7

• cornea: this is transparent, protects the eye from foreign particles, and allows light to pass through it by refracting the light rays.
• lens: it focuses the images to allow you to see and send this information to the retina

Question 8

state the 2 sense receptors present in the retina and their function

Answer 8

• rods: allows you to see black and white
• cones: allows you to see colour

Question 9

what is the function of the retina

Answer 9

contains nerve cells (rods and cones) that detect and transfer this mssage to the optic nerve

Question 10

function of the optic nerve

Answer 10

carries signals from the retina to the brain

Question 11

function of the choroid

Answer 11

ensures the light isn’t further refracted in the eye

Question 12

what is the blind spot

Answer 12

where no rods or cones are present

Question 13

what is the fova/yellow spot

Answer 13

part of the eye that contains a high concentration of rods

Question 14

function of the cillary muscles

Answer 14

pulls the lens (to make them tighter) and allows them to relax (to make them thicker) it does this to focus an image on the retina.

Question 15

what is accomodation as it pertains to the eye

Answer 15

it refers to the adjustment of the lens of the eyeballs so that clear images of objects at different distances are formed on the retina.

Question 16

explain the 3 parts of the process that allows images to be formed

Answer 16

1. the cornea refracts the light to go through the pupil and to the lens.
2. the lens bend and focus the image on the retina (upside down) and then interpreted by the brain.
3. once the nerve cells in the retina send this image/message to the brain, to allow you to see the image right-side-up (how it should be).

Question 17

what happens to the lens in the eye when we look at images up close

Answer 17

the lens gets bulged/flattened. this is created when the ligaments relax and the muscles contract and hence a convex lens is made.