lecture 4

Question 1

name the steps in the visual pathway

Answer 1

eye optic nerve optic chiasm optic tract LGN optic radiation visual cortex.

Question 2

what provides oxygen to the cornea

Answer 2

tear film

Question 3

what is the cornea made of mostly how are they arranges and why

Answer 3

mostly collagen fibres in parallel to improve trasnsparacy

Question 4

what is myopia caused by

Answer 4

a long eye (short sighted )

Question 5

what is hypermetropia caused by

Answer 5

a long eye (long sighted)

Question 6

what are the structures seen in the iris

Answer 6

pigmented epithelial layer- blocks out light
stroll layer -eye colour

Question 7

what do midractics do?

Answer 7

dilate the eye

Question 8

what is the mechsm of action for atropine

Answer 8

Ach antagmoist, so blocks parhasypatic control

Question 9

what is the aqueous humour formed by

Answer 9

cilliary processes on the edged of the cilliary muscle

Question 10

what does the aqueous humour drain through?

Answer 10

the trabecular meshwork into the schemes canal

Question 11

what is glaucoma?

Answer 11

a problem of drainage off aqueous humour, leading to pressure build up in the eye damaging axons and leading to vision loss

Question 12

how do we treat glaucoma

Answer 12

beta blockers to reduce the formation of aqueous humour

Question 13

what is the sclera

Answer 13

the protective white outer part of the eye comprised of elastin and collagen

Question 14

why do humans have more sclera then other species

Answer 14

so we can use eye movements for communication

Question 15

what is the choroid

Answer 15

a vascular layer that roves oxygen to outer retina especially the fovea

Question 16

how is the feova related to age related macular degeneration?

Answer 16

abnormal blood vessels grow out of the choroid

Question 17

what is the retinal pigment epithelium?

Answer 17

pigmented layer for light absorption

Question 18

what is the purpose of the retinal pigment epithelium?

Answer 18

to reduce oxidative stress form the bbb and phasgotise photoreceptor discs

Question 19

what are horizontal cells?

Answer 19

interneurons that connect photoreceptors latterly

Question 20

what do horizontal cells do

Answer 20

allow for forming inhibitory compost of visual feild in order for contrast detection

Question 21

what do bipolar cells do?

Answer 21

connect photoreceptors to retinal ganglion cells, facilitate sensory processing through horizontal and amacrine cells

Question 22

how do bipolar cells communicate?

Answer 22

via graded potentials

Question 23

what do amacrine cells do?

Answer 23

connect bipolar cells laterally, and sense movement to enable motion dectection in the retina

Question 24

what are retinal ganglion cells?

Answer 24

output cells from the retina

Question 25

how is the central retina specified for have spatial vision?

Answer 25

long narrow cone outer segments allow for high density packing, obliquely run hence fibres -the axons of cones forms the foveal pit
and ganglion cells heaped up around the fovea

Question 26

how do photoreceptors work?

Answer 26

depolarised in the dark
disks contain photopigments such as rhodpsin
when these are exposed to light then Na+ channels close
hyperporises the cell
reduced glutamate release