Kin 131 exam

Question 1

What is neroplasticity and how and when does it happen?

Answer 1

Is the change in the brain
- Brain adapts over whole life
- Brain changes in response to everything

Question 2

Explain what phantom limb sensation is

Answer 2

-When people feel sensations on parts of their body that aren’t there anymore when stimulus is felt on different parts of the body.
- Because when a part of the body is gone, the area of the brain that was previously for that has been taken over by neurons for other parts of the body and the brain can misinterpret the stimulus as coming from the missing limb

Question 3

What are the 5 special senses?

Answer 3

Vision, Audition, Vestibular, Gustation, olfaction

Question 4

Explain the 3 layers of the eye

Answer 4

1. Sclera
   - Tough ouster layer of connective tissue
   - muscles that rotate eye attach here
   - Cornea: front outside layer of the sclera that protects it and allows light into the eye
2. Choroid
   - middle thin layer
   - Darkly coloured in order to pick up light rays at the back of the eye that arent absorbed by cones and rods

• Iris: Coloured part of the eye that controls the diameter of the pupil, therefore the amount of light entering the eye
• Zonular fibers: connect the cillary muscles to the lens.
• Cillary muscles: Change the shape of the lens, controlling far/close vision
  Lens: Clear structure that light passes through

3. Retina
   - Inner most layer
   - Considered extension of the CNS
   - Where the photoreceptors sit

• macula lutea: Area with little blood vessels that house the fovea centrais
• Fovia centralis: Area with high density of cone cells
• Optic discs: Area where the optic nerve leaves the eye that contains no photoreceptors. Photoreceptors create electric signals carried by neurons which converge to create the optic nerve which leaves the eye vis the optic disk (blind spot)

Question 5

Explain the inside of the eye

Answer 5

Aqueous humour: Fluid that fills the space between the iris and the conea

• Vitreus humor: Jelly like substance that sits between the lens and the retina. fills eyeball

Question 6

Explain the refraction of light in the eye

Answer 6

Lens bends light in order to hit the retina. Closer object = lens is more bent

Question 7

Explain how the Cillary muscle works

Answer 7

• When relaxed the the lense is pulled flat
• When contracted the tension is taken off of the zonular fibers, allowing the lens to bend
• Cillary muscles also attach to the iris, causing dilation or constriction of the iris

Question 8

explain far and near sightedness and what can cause it

Answer 8

Myopia:
- Near sightedness
- Typically have a extended eyeball, causing light to converge infant of the retina
- can be corrected with a concave lens

Hyperopia:
- Typically have a shortened eyeball causing light rays to converge behind the retina
- Can be corrected with a convex lens

-Age causes lens to lose elasticity causing myopia and hyperopia

Question 9

Is the retina considered part of the CNS or the PNS?

Answer 9

PNS because it has a high number of specialized cells

Question 10

What are the two types of photoreceptor cells? What do they do?

Answer 10

Rods and cones. Turn light to electrical signals for the brain to understand

• Are bipolar neurons
• Dendrites are ‘disks’ that respond to light

Question 11

Explain rods

Answer 11

• Contain rhodopsin which is extremely sensitive to light, even in the dark
• No roll in colour vision
• More inactive in bright environments, but active in dark environments
• take time to fire up when going from light to dark area

Question 12

Explain Cones

Answer 12

• Less sensitive to light
• Primary roll is colour vision
• 3 different types of cone cells that sense different colours (sense different wavelengths)
• Some people have a 4th type of cone and can see extra colours
• Cones are better for perceiving detail

Question 13

Explain the process of light being perceived by the brain

Answer 13

1. Light enters eye and gets picked up by rods and cones
2. Light that didn’t get picked up gets absorbed by the choroid at the back of the eye
3. light that hit rods and cones create a graded potential which heads down the rods and cones and interacts with bipolar cells
4. The signal is carried through the bipolar cells to a retinal ganglion cells, which take the signal and pass it to its long axons which converge creating the optic nerve
5. Signals going to brain can be excitatory or inhibitory, controlling what info goes to the brain in order to create a clear image for the brain

Question 14

What photoreceptor is more effective in bright light

Answer 14

cones, because their less sensitive to light

Question 15

Which way do the photoreceptors face in the eyeball?

Answer 15

Face to the back of the eye, facing the retina

Question 16

What do horizontal cells and amacrine cells do?

Answer 16

Coordinate info from adjacent receptor cells helping us understand shape and movement

Question 17

what do muller cells do?

Answer 17

Act as a funnel to let light travel to the back of the eye without being disrupted