Visual System

Question 1

What is the first order neurone in the visual system?

Answer 1

Bipolar cells

Question 2

Where is the second order neurone in the visual system?

Answer 2

ganglion cells - axon forms optic nerve

Question 3

what are the interneurones of the retina?

Answer 3

horizontal cells

amacrine cells

Question 4

Objects in one lateral half of the visual field form images on the …… half of the ipsilateral retina and the ….. half of the contralateral retina.

Answer 4

nasal

temporal

Question 5

At the chiasm, which part of the retinal field will decuss to the contralateral side?

Answer 5

Nasal side

Question 6

Where does the second order neurones of the visual system, i.e. the optic nerves terminate?

Answer 6

lateral geniculate nucleus of the thalamus

Question 7

A small number of fibres leave the optiv nerve before reaching the lateral geniculate, where do they do?

Answer 7

Pretectal area

superior colliculus

• mediation of the pupillary light reflex

Question 8

What happens in the visual association cortex?

Answer 8

interpretation of visual images, recognition, depth perception, and colour vision

Question 9

IMPORTANT NOTE about the visual field

Answer 9

objects in either half (left or right) of the visual field produce images upon the nasal hemiretina of the ipsilateral eye and the temporal hemiretina of the contralateral eye

Question 10

The combination of images from both eyes is necessary for …

Answer 10

stereoscopic vision (depth perception)

Question 11

Fibres representating the upper part of the visual field sweep into the temporal lobe, called the ……

Answer 11

Meyer’s loop

Question 12

upper left quadrant of the visual field is represented in the …… …….. quadrant of the visual cortex

Answer 12

lower right

Question 13

Diagram of the eye

Answer 13

Question 14

What is the consequence of raised intraocular pressure (glaucoma)?

Answer 14

problems with blood supply to the eye and blindness

Question 15

Ocular fluid is secreted by the……

Answer 15

ciliary body

Question 16

Which reflexes are initiated by hte nociceptive sensory axons of the corneal epithelium?

Answer 16

The corneal reflex, via the ophthalmic division of V (sensory)

closing the eye reflex - motor branch of VII to orbicularis oculi

Question 17

Where does the cornea get it’s nutrition

Answer 17

tears

Question 18

The retina is an extension of which part of the brain?

Answer 18

diencephalon

Question 19

What does each photoreceptor cell synapse with?

Answer 19

Two types of bipolar cell

an “on” bipolar activated in the light (but inhibited in the dark by glutamate), and an “off” bipolar activated in the dark.

Thus the visual pathway detects both light and the absence of light.

Question 20

Important action of the pigment epithelium, what is it?

Answer 20

Destroys worn out rod and cone membrane (this mechanism fails in retinitis pigmentosa, causing debris accumulation and blindness)

Question 21

What do horizontal cells do?

Answer 21

Form inhibitory surrounds to areas of maximum brightness, increasing image contrast

Question 22

What do amacrine cells do?

Answer 22

Further process the image, allowing detection of movement, adjusting brightness and other complex image features etc.

Question 23

Meyer’s loop is part of the ….

Answer 23

visual radiation

Question 24

Visual field defects

Answer 24

Question 25

What is this called?

Answer 25

Bitemporal hemianopia

Question 26

What’s the name of this?

Answer 26

Homonymous hemianopia