Receptors

Question 1

Rod cells

Answer 1

-Rod-shaped
-1 type
-Greater number
-More at peripheral, none at fovea
-poor visual acuity
-High sensitivity to low light

Question 2

Cone cells

Answer 2

-Cone shaped
-3 types
-Fewer numbers than rod
-Concentrated in the fovea, fewer at peripheral
-Good visual acuity
-Low sensitivity to low light

Question 3

How is a generator potential produced

Answer 3

Optical pigments absorb light, pigments are then broken down which results in the production of a generator potential.

Question 4

Distribution of rod & cone cells

Answer 4

-Uneven distribution
-Most cone cells located near the fovea
-Rod cells located farther away

Question 5

Pacinian corpuscles

Answer 5

Pressure receptors located deep in the skin, mainly in feet + fingers

Question 6

Resting potential of Pacinian corpuscles maintained by

Answer 6

1. Sodum pottasium pump
2. Na+ voltage-gated channels mostly closed
3. K+ voltage-gated channels mostly open

Question 7

Generator potential in a Pacinian Corpuscle

Answer 7

1. When pressure is applied, the capsule distorts
2. Deforming the nerve ending inside, opens the Na+ ions channels inside
3. Na+ ions diffuse into the cell through the stretch-mediated Na+ ion channels, down conc gradient
4. Membrane becomes depolarised
5. So, more Na+ ion channels open, therefore more Na+ ions diffuse in
6. Leads to a generator potential being established