Retina

Question 1

Retina

Answer 1

1. Pigmented later
2. Nervous layer:
   A.1. Photoreceptors
3. Rod cells
4. Cone cells
   B.1. Neural layer
5. Blind spot
6. Yellow spot

Question 2

Pigmented layer

Answer 2

Structure: this pigmented layer of cuboidal cells birders on the choroid
Function: the dark pigment these cells contain help absorb light

Question 3

Photoreceptors

Answer 3

There are two types: rods and cones
- they are modified neurons
- both sensitive to light
Photoreceptors convert light stimuli into nerve impulses

Question 4

Rod cells

Answer 4

Structure: They are about 140 mil of these think elongated cells per eye
- they are found mainly in the peripheral regions of the retina
Function:
1. Respond to low-intensity and provide night (black and white)
2. They provide peripheral vision

Question 5

Cone cells

Answer 5

Structure:
There are about 7 mil of these flatter cells per eye, found mainly in the yellow spot of the retina. Red, blue and green cones each respond to different wavelengths of light
Function:
1. The respond to bright-light intensity and enable colour to be scene
2. They provide sharp, clearer vision

Question 6

Neural layer

Answer 6

Structure:
Layer of photoreceptors synapses with two layers of neurons. The axons of the second layer form the optic nerve which leaves the eye
Functions:
1. These neurons carry impulses from the photoreceptors
2. The optic nerve conducts impulses to the occipital lobe of the cortex where they are interpreted as sight

Question 7

Blind spot

Answer 7

Structure:
- there are no rods or cones where the optic nerve leaves the eyeball
- blood vessels enter and leave the eye here
Functions:
This spot is not sensitive to light stimuli

Question 8

Yellow

Answer 8

Structure:
- near the centre of the retina, to the side of the blind spot, is an oval area, the yellowspot
- the yellow spot contains mainly cones
Functions:
The yellow spot is the region of highest vacuum acuity, i.e. where vision is sharpest