Physiology: The Retina

Question 1

what is the function of the photoreceptor layer of the retina

Answer 1

responsible for phototransduction, ie converting light into electrical signal

Question 2

describe the direct(vertical) pathway for signal transmission in the retina, from internal to external

Answer 2

photoreceptors => bipolar cells => ganglion cells => to the brain via optic nerve
(so light passes through other cell types to reach photoreceptors)

Question 3

what are the 2 different types of cells that form lateral connections that influence signal processing in the retina

Answer 3

horizontal cells and amacrine cells

many different types of each of these in different parts of retina

Question 4

describe the function of horizontal cells in the retina

Answer 4

receive input from photoreceptors and project to other photoreceptors and bipolar cells

Question 5

describe the function of amacrine cells in the retina

Answer 5

receive input from bipolar cells and project to ganglion cells, bipolar cells and other amacrine cells

Question 6

what are the 4 main regions of the structure of a photoreceptor

Answer 6

outer segment(containing the photopigment, ie cone or rod), inner segment, cell body and synaptic terminal

Question 7

what are the different types of photoreceptors

Answer 7

rods and cones

Question 8

describe the resting membrane potential of photoreceptors

Answer 8

depolarised resting membrane potential(Vm), more positive than other neurones at around -20mV

Question 9

what happens to the Vm of photoreceptors in response to light

Answer 9

hyperpolarises