week 7

Question 1

What is vison

Answer 1

Our most dominant sense
Assists with locating objects, in collaboration with other senses

Question 2

What is Cornea

Answer 2

Clear; main lens of the eye

Question 3

What is aqueous humour

Answer 3

watery fluid in anterior chamber

Question 4

What is the iris

Answer 4

our eye colour

Question 5

Pupil

Answer 5

dark aperture in front of the lens

Question 6

What is lens

Answer 6

Adjustable lens to supplement cornea

Question 7

What is ciliary body

Answer 7

includes ciliary muscle, which controls shape of lens; manufactures aqueous humour

Question 8

What is vitreous humour

Answer 8

Jelly-like liquid between lens and retina

Question 9

What is Extraocular muscles

Answer 9

attached to sclera move the eye

Question 10

What is the path of light into the eye

Answer 10

Light enters directly through pupil, hitting light sensitive receptors at back of retina

Question 11

What is path of vison the cornea to the retina

Answer 11

As light enters, it’s bent by the cornea, travels through the pupil, and bent again by lens. Curvature of cornea is fixed, muscles adjust curvature of lens to focus on near/far objects, Creates an inverted, backwards image

Question 12

What does the lens do

Answer 12

emmetropic-normal vision
Vision problems occur when the focal point of light refraction is in front or behind the retina causes blurred vision

Question 13

Bad lenses

Answer 13

Hypermetropic eye-long-sighted vision this is called by Hyperopia. It is corrected with a converging lens

Myopic eye-short-sighted vision called Myopia. This is corrected with a diverging lens

Question 14

Effect of age on the eye

Answer 14

Presbyopic eye- sad, old people’s vision
Lens is no longer flexible enough to change shape can no longer focus on close and distant objects

Question 15

What is Retina

Answer 15

Composed of photoreceptors with layer of neurons connected on top
Light passes straight to the photoreceptors at the back of retina, Neurons and receptors translate light into action potentials

Question 16

What is Fovea

Answer 16

0.3 mm in diameter, centre of vison field
A small dimple in the retina denser receptors at centre
Sharpest vison, densest colour receptors
Makes reading possible

Question 17

What is the blind spot

Answer 17

small area of retina where the blood vessels enter and exit. It has no photoreceptors

Question 18

What is photoreceptors

Answer 18

Light triggers chemical reaction change membrane potential
two types: cones- tapered at end, 6-7 million
Rods- long cylindrical shape at one end, 120 million

Question 19

What is the structure of photoreceptors with colour

Answer 19

small, densely packed, distinguish colours in bright light

Question 20

What is the structure of receptors for colour (black and white)

Answer 20

Larger and more scattered, have 2 mile sensitivity to a single slight source

Question 21

What are rods

Answer 21

very sensitive to low luminescence
Works in broader spectrum of conditions: Night vision: slow dark adaptation, low acuity, starts at periphery
None in Fovea
has only one colour receptor rhodopsin

Question 22

What are cones

Answer 22

Don’t respond to dim light but very responsive to bright light
they detect colour and help us see fine detail: high acuity
Highly concentrated in fovea
Has 3 colour receptors red, green and blue

Question 23

What is colour

Answer 23

red , green, red (cones) and light (rod)
roughly equal red and green
less blue, so not as sensitive
colour is a mixture-> they aren’t separate

Question 24

Colour blind

Answer 24

Coded on X chromosome because of this men are more likely to be colour blind and women sometime s have more distinctive colour vision

Question 25

What are retinal neurons

Answer 25

4 types: bipolar, horizontal, amacrine and ganglion cells
Retinal ganglion cells have two categories in primates: magnocellular (M-cells) and parvocellular (P-cells) cells.

Question 26

What are M-cells

Answer 26

sensitive to light, not colour, and get information mostly from rods- project to magnocellular layer of lateral geniculate nucleus

Question 27

What is P-cells

Answer 27

smaller, and get information mostly from cones, so more sensitive to colour. Project to parvocellular layer of lateral geniculate nucleus

Question 28

What is visual pathway

Answer 28

Retinal cell ganglia form the optic nerve, Optic chiasm is where the pathways from each eye cross, Medial path of each retina crosses to opposite side, Lateral path goes straight back

Question 29

What is Geniculostriate system

Answer 29

All p ganglion and some m ganglion form this pathway- Goes from retina to lateral geniculate nucleus of thalamus and via optic radiations to layer 4 primary visual cortex in the occipital lobe- Visual cortex takes information about colour, form and motion

Question 30

What is Tectopulvinar system

Answer 30

Other path made up of remaining M ganglion cells-> sends axons to superior colliculus where sends connections to pulvinar region of the thalamus-> pulvinar sends information to parietal and temporal lobes