S15 Somatosensory physiology.

Question 1

What are the four main classes of somatosensory receptors?

Answer 1

Tactile: merkel, ruffini, meissner, pacinian.
Proprioception: spindle and golgi.
Thermal: thermoreceptors.
Nociceptive: mechanical, thermal, polymodal.

Question 2

Which fibre types are mechanoreceptor afferent innervated by?

Answer 2

Aβ.

Question 3

Merkel cell receptor:

Adaptation speed, position and role.

Answer 3

Slow. Epidermal-dermal border. Pressure.

Question 4

Which mechanoreceptors encode braille inputs?

Answer 4

Merkel afferents.

Question 5

Which molecule is the basis of the burning sensation in the mouth after eating chilli? How does it work?

Answer 5

Capsaicin. Acts on thermal receptors expressing VRC1. Produce inwards Ca+ current. Also activated by heat.

Question 6

Describe the classification of sensory afferent nerves.

Answer 6

Aα : Group 1: largest + fastest.
Aβ : Group 2.
Aδ : Group 3.
C : Group 4: smallest and slowest.

Question 7

Advantages and disadvantages of overlapping dermatomes?

Answer 7

Damage doesn’t lose all sensation.

Harder to localise pain.

Question 8

What is asteroagnosia?

Answer 8

The inability to identify objects on the basis of touch alone.

Question 9

Meissner cell receptor:

Adaptation speed, position and role.

Answer 9

Rapid. Below epidermis. Flutter + motion.

Question 10

Ruffini ending:

Adaptation speed, position and role.

Answer 10

Slowly. Deep. Skin stretch.

Question 11

Pacinian corpuscle:

Adaptation speed, position and role.

Answer 11

Rapid. Deep. Vibration.

Question 12

Which types of neurones are associated with

proprioception?

Answer 12

Aα/Group 1.

Question 13

Which types of neurones are associated with nociceptors and thermoreceptors?

Answer 13

Aδ/Group 3.

C/Group 4.

Question 14

What is neglect syndrome?

Answer 14

Body part or visual field is disregarded.