Practice Questions - Week 5 - Somatosensory System

Question 1

Which of the following is/are features of warm receptors?

1. an increase in action potential frequency as the skin temperature decreases
2. small diameter myelinated axons
3. conduction velocities in the range of 12 - 30 m.sec-1

a) 1 only
b) None of these are features of warm receptors
c) 1 & 3 only
d) 1, 2 & 3
e) 2 & 3 only

Answer 1

b)

Question 2

Which of the following sensations is not part of the somatosensory system?

1. sensations that arise from smooth muscle
2. sensations that arise from joints
3. sensations that arise from the skin.
4. sensations that arise from the ear
5. sensations that arise from skeletal muscle

Answer 2

4.

Question 3

The axons of the second order neurones in the thermoreceptive pathway cross the midline at which of the following locations?

1. below the central canal of the spinal cord
2. in the ventrobasal complex of the thalamus
3. in the ventrolateral funiculus
4. in the dorsal columns
5. in the medulla oblongata

Answer 3

1.

Question 4

Which of the following classes of neurone is/are normally spontaneously active?

1. warm thermoreceptors

2.cold thermoreceptors

3. touch receptors

a) only 1 & 2

b) only 3

c) only 1

d) only 2

e) only 1 & 3

Answer 4

a)

Question 5

The differing proportions of mechanosensitive spots on the surface of the skin in different body regions are a consequence of which of the following?

1. innervation density
2. skin thickness
3. frequency encoding
4. receptor adaptation
5. receptor sensitivity

Answer 5

1.

Question 6

The difficulty that most subjects experience in locating the position of a light object placed on their forearm skin 10-15 seconds after it has been placed there is due to?

frequency encoding

innovation density

receptor adaptation

receptor sensitivity

innervation density

Answer 6

Receptor adaptation

Question 7

Pacinian corpuscles are associated with which of the following class of neurone?

a) rapidly adapting thermoreceptors

b) slowly adapting mechanoreceptors

c) rapidly adapting mechanoreceptors

d) very rapidly adapting mechanoreceptors

e) slowly adapting cutaneoreceptors

Answer 7

d)

Question 8

The area of somatosensory cortex that is dedicated to different parts of the homunculus is determined by which of the following?

a) the size of the body region

b) how often you use the area

c) the innervation density of the body region

d) the type of receptors which innervate the region

e) the number of sensory neurones which innervate the body region

Answer 8

c)

Question 9

Which of the following classes of neurone have axons that terminate in the thalamus?

1. touch receptors
2. polymodal nociceptors
3. thalamocortical neurones

1 only

none of them

1 & 2 only

1, 2 & 3

2 only

Answer 9

none of them

Question 10

The class of neurons that provides information about the rate of application of a low threshold mechanical stimulus would be an example of which of the following?

a) slowly adapting mechanoreceptor

b) very rapidly adapting mechanoreceptor

c) slowly adapting cutaneoreceptor

d) rapidly adapting thermoreceptor

e) rapidly adapting mechanoreceptor

Answer 10

e)

Question 11

In humans the homunculus is located in which of the following regions?

a) precentral gyrus of the parietal lobe

b) brain stem

c) ventrobasal complex

d) postcentral gyrus of the parietal lobe

e) postcentral gyrus of the frontal lobe

Answer 11

d)

Question 12

The cell bodies of the third order neurones in the mechanoreceptive pathway are located in which of the following structures?

a) below the central canal of the spinal cord

b) in the medulla oblongata

c) in the ventrobasal complex of the thalamus

d) in the dorsal columns

e) in the ventrolateral funiculus

Answer 12

c)

Question 13

The neurones that encode information about a sustained skin deformation (indentation) have which of the following features?

1. responds in a sustained fashion to skin indentation.
2. action potential frequency that is directly proportion to the size of the indentation.
3. little adaptation to a sustained response.
4. specialised receptors known as Ruffini’s endings.
5. specialised receptors known as Merkel’s corpuscles.

1, 2, 3, 4 & 5

1, 3 & 5 only

2, 3 & 5 only

1, 2, 3 & 4 only

2, 3 & 4 only

Answer 13

1, 2, 3, 4 & 5

Question 14

Which one of the following is NOT a feature of cold receptors?

a) decreased action potential frequency as the skin temperature decreases

b) small diameter myelinated axons

c) cells bodies in the dorsal (posterior) root ganglia

d) axons with conduction velocities in the range 12 - 30 m.sec-1

e) axon terminals in the dorsal (posterior) horn on the spinal cord

Answer 14

a)

Question 15

The term that describes the number of neurones that innervate a particular surface area of the skin is which of the following?

a) innervation area.

b) innovation density.

c) innervation density.

d) receptive field size.

e) homunculus.

Answer 15

c)

Question 16

Which of the following is/are a feature of transduction in the somatosensory system?

1. stretch-gated ion channels
2. ligand-gated ion channels
3. temperature-gated ion channels

1 & 2 only

1, 2 & 3

3 only

1 only

2 only

Answer 16

1, 2 & 3

Question 17

Which of the following sensations is/are NOT a type of mechanoreception?

1. sharp pain
2. touch
3. vibration
4. warmth

2 & 3 only

1 only

1, 3 & 4 only

4 only

1 & 4 only

Answer 17

1 & 4 only

Question 18

Why are Von Frey hairs useful tools in the study of the somatosensory system?

a) because they are named after a famous German physiologist

b) because they selectively activate very rapidly adapting low threshold mechanoreceptors

c) because they produce temporally appropriate mechanical stimuli

d) because they selectively activate rapidly adapting low threshold mechanoreceptors

e) because they produce consistent skin indentations from trial to trial

Answer 18

e)