Receptors

Question 1

What receptor do we look at detects changes in mechanical pressure?

Answer 1

Pacinian Corpuscle

Question 2

Features of the Pacinian Corpuscle

Answer 2

Specific to a single stimulus - mechanical pressure
Produces a generator potential by acting as a transducer

Question 3

What is a transducer

Answer 3

Something that translates physical or chemical stimuli into electrical or chemical signals which can be processed by the organism

Question 4

Where is the pacinian corpuscle found?

Answer 4

Deep in the skin
Fingers
Sole of feet
External genetalia
Ligaments
Tendons

Question 5

From outside to inside, what is the structure of the Pacinian corpuslce?

Answer 5

Capsule
Blood capillary
Layers of connective tissue with viscous gel between
Neurone ending

Question 6

In what part of the Pacinian corpuscle are the stretch mediated sodium channels found?

Answer 6

In the sensory neurone ending

Question 7

Why are stretched mediated sodium channels called this?

Answer 7

Because their permeability to sodium changes when deformed

Question 8

How does the Pacinian Corpuscle work? (Process)

Answer 8

In resting state, stretch mediated sodium channels are closed and so has a resting potential
When pressure is applied to Pacinian Corpuscle, it is deformed and membrane around neurone is stretched
Stretching opens sodium channels in the membrane
Sodium ions diffuse into neurone
Influx of sodium ions depolarises the membrane, producing generator potential
Generator potential turns into action potential, passing along the neurone to other neurones and then to CNS

Question 9

What 2 receptors can be found in the eye?

Answer 9

Rod cells
Cone cells

Question 10

Other than receptors, what can the pacinian corpuscle, rod and cone cells be otherwise called?

Answer 10

Transducers

Question 11

What do rod and cone cells detect?

Answer 11

Light

Question 12

What can cone cells do that rod cells cannot do + why?

Answer 12

Distinguish different wavelengths of light
Because
3 types of cone cells, 1 type of rod cell

Question 13

What type of receptor is most abundant in the eye?

Answer 13

Rod cells

Question 14

How is a generator potential produced in rod cells?

Answer 14

The rhodopsin pigment is broken down in low intensity light, causing a generator potential.

Question 15

Why do rod cells give poor visual acuity?

Answer 15

Many rod cells are connected to one bipolar neurone.
This means only 1 impulse can be sent to the brain regardless of how many cells are stimulated
The brain therefore cannot distinguish the seperate sources of light

Question 16

Why can rod cells be stimulated in low intensity light?

Answer 16

Rod cells have retinal convergence
This means there is a greater chance of the threshold value being exceeded which leads to generator potential

Question 17

What is meant by retinal convergence

Answer 17

Multiple rod cells connected to one bipolar neurone

Question 18

Where are rod cells primarily found in the eye?

Answer 18

Periphery of the retina
Absent at fovea

Question 19

Where re cone cells primarily found in the eye?

Answer 19

Fovea
few in periphary

Question 20

Why is high light intensity required to stimulate cone cells?

Answer 20

Each cone cell has their own bipolar neurone
No retinal convergence
Greater stimulation required to exceed threshold and produce generator potential.

Question 21

How do cone cells produce a generator potential?

Answer 21

The pigment iodopsin is broken down by high intensity light, producing generator potential.

Question 22

Why do cone cells have a high visual acuity?

Answer 22

Each cone cell is connected to its own bipolar neurone
Each cone cell produces its own generator potential and impulse to the brain.
Brain therefore can distinguish separate sources of light