Week 1 - I - Retina and vision (physiology 2)

Question 1

What are the two types of photoreceptors in the reitna of the eye?

Answer 1

There are rods and cones

Question 2

Which out of rods and cones respond for peripheral vision and which for central vision?

Answer 2

Rods are found on the circumference of the retina and are used in peripheral vision

Cones are used for central vision and are in very high density in the fovea of the eye

Question 3

What is phototransduction?

What carries this out in the eyes?

Answer 3

Converts electromagnetic radiation (the waves of photons) to neural signals

This is carried out by the photoreceptors found on the retina of the eye

Question 4

Direction of light travels from the front to the back of the eye where it hits the photoreceptors

What are the four segments of the photoreceptor?

Answer 4

Consisit of an outer segment, an inner segment, cell body and a synaptic terminal

Question 5

What acts to transmit the signal from the synaptic terminal of the photoreceptor to the ganglion cell?

Answer 5

The bipolar cells trasmits this signal

Question 6

In the outer segments of rods, there are membranous folds containing biological pigments that extremely sensitive to light

WHat re these pigments known as?

Answer 6

Rhodopsin

Question 7

Rhodopsin consists of a vitamin A derivative and a Gprotein coupled receptor

What are they known as?

Answer 7

Vitamin A derivative = retinal

GPCR - ospin

This is why vitamin A helps you see in the dark as it produces the pigments that help you see in the dark

Question 8

In the dark, the dark channels of the rod open releasing what neurotransmitter?

Answer 8

Releases more glutamate

Question 9

What do the ganglion cells join to form after recieving the axons from the bipolar cells?

Answer 9

Join to form the optic nerve which then travels to the primary visual areas in the occipital lobes

Question 10

Ability to distinguish two nearby points. Determined largely by photoreceptor spacing and refractive power
What is this?

Answer 10

Visual acuity - clarity of vision

Question 11

In the center of the fovea there is a huge increase in cones with a mass decrease in rods (no rods)

As moving more peripheral from the fovea the rods increase and cones decrease

Which is for seeing in daylight and which is for dim light?

Answer 11

Cones allow you to see in daylight

Rods allow you to see in dim light- cones are for fine detail as they are the center of vision