14.4 Receptord

Question 1

What do pacinian copuscles respond to

Answer 1

Mechanical pressure

Question 2

What are sensory responses specific to

Answer 2

A single type of stimulus. It will not respond to any other stimulus

Question 3

How do sensory responses produce a generator potential

Answer 3

By acting as a transducer

Question 4

What is the role of the transducer

Answer 4

To convert the change in form of energy by the stimulus into a form, namely nerve impulses, that can be understood by the body

Question 5

What do receptors in the nervous system convert the energy of the stimulus into

Answer 5

A nervous impulse known as a generator potential

Question 6

What does the sensory neurone at the centre of the pacinian corpuscle have

Answer 6

A special type of sodium channel in its plasma membrane

Question 7

What is the special type of sodium channel the sensory neurone at the centre of the pacinian corpuscle called

Answer 7

A stretch-mediated sodium channel

Question 8

Why are stretch-mediated sodium channels called stretch-mediated

Answer 8

Because their permeability to sodium changes when they are deformed - e.g. when stretched

Question 9

How do pacinian corpuscles function

Answer 9

1. In its normal unstretched resting state, the SM-sodium channels of the membrane around the neurone are too narrow to allow sodium ions to pass along them. At this state, the neurone has a resting potential
2. When pressure is applied to the pacinian corpuscle, it is deformed and the membrane around its neurone becomes stretched
3. The stretching widens the sodium channels and sodium ions diffuse into the neurone
4. The influx of sodium ions changes the potential of the membrane, thereby producing a generator potential
5. The generator potential in turn creates an action potential (nerve impulse) that passes along the neurone ans then, via other neurones, to the CNS

Question 10

What are the two types of light receptor cells found on the retina

Answer 10

1. Rod cells

2. Cone cells

Question 11

How do both rod and cone cells act as transducers

Answer 11

By conserving light energy into electrical energy of a nerve impulse

Question 12

Describe the differences between Rod and Cone cells

Answer 12

1. Rod cells are rod shaped, cone cells are cone shaped
2. There are greater numbers of rod cells than cone cells
3. There are more rod cells at the periphery of the retina than cone cells, and there are more cone cells at the fovea than rod cells.
4. Rod cells give poor visual acuity, Cone cells give good visual acuity
5. Rod cells are sensitive to low intensity light, Cone cells are sensitive to high intensity light
6. There is 1 type of rod cell, but multiple types of cone cells each corresponding to different wavelengths