The Eye

Question 1

Receptors

Answer 1

A cell or group of cells that detects a stimulus eg heat or light

Question 2

A sense organ

Answer 2

An assembly of specialised sensory receptors
Eg skin nose tongue eye and ear

Question 3

Conjunctiva

Answer 3

Function- protects against infection and moistens the eye

Question 4

Sclera (white of the eye)

Answer 4

Function- allows no light thru and keeps the shape of the eye

Question 5

Cornea

Answer 5

Function- bends light towards retina
Adaptation- curved and transparent

Question 6

Choroid (dark coloured layer)

Answer 6

Function- ensures there is no internal reflection of light inside the eye
-has blood vessels to nourish the eye

Question 7

Iris (coloured muscular part of the eye)

Answer 7

Function- controls the amount of light entering the eye by controlling the diameter of the pupil
-this is done by muscular contraction in response to light

Question 8

In bright light

Answer 8

Iris relaxes ( gets longer)
Pupil gets smaller , less light enters the eye

Question 9

In dim light

Answer 9

-iris contracts ( gets smaller )
-the pupil gets higher , more light enters the eye

Question 10

Pupil( opening in the iris)

Answer 10

Function- allows light into the back of the eye

Question 11

Lens

Answer 11

Function- to focus light onto the retina
Adaptation- curved , elastic and transparent

Question 12

Ciliary muscle

Answer 12

-surrounds the lens and causes the shape of the lens to change when we look at near or far objects
-the changing of shape of the lens is a reflex action known as accommodation

Question 13

Suspensory ligaments

Answer 13

-function- hold the lens in place
-attaches the ciliary muscles to the lens

Question 14

Retina

Answer 14

Function-converts light into nerve impulses
2 types of light receptor cells which convert the light into the retina
Rods and cones

Question 15

Rods

Answer 15

Detects balck and white vision and vision in dim lights - found all over retina

Question 16

Cones

Answer 16

Detects colour vision and vision in bright lights- found mostly at fovea

Question 17

Fovea

Answer 17

Function- most images are focused here
-also known as the yellow spot

Question 18

Blind spot

Answer 18

Where the optic never leaves the eye , no rods or cones here

Question 19

Optic nerve

Answer 19

Brings impulses from the retina to the brain

Question 20

Aqueous humour

Answer 20

Salt solutions that holds the front of the eye in shape

Question 21

Virtuous humour

Answer 21

Fluid that fills the rear of the eye
It gives shape to the eye and supoorts the lens

Question 22

External muscles

Answer 22

Pull on the eye causing it to change direction

Question 23

Why two eyes are better than one

Answer 23

-3D vision
Can judge distance of objects
-increases visual field