Practical 1

Question 1

What afferent fibres are present within the human skin?

Answer 1

Aβ, Aδ, and C fibers.

Question 2

What are A-beta afferent fibres?

Answer 2

Large and myelinated Aβ fibers are normally not involved in pain transmission but respond to light touch and convey tactile information.

Question 3

What are Aδ fibers?

Answer 3

Aδ fibers are thinly myelinated nerves transmitting stimuli to the central nervous system.
They respond to mechanical stimulation, especially pinching or pinprick.
In the skin, Aδ fibers are mainly specialized for detection of potentially dangerous mechanical and thermal stressors and for triggering a rapid response and protective reflexes.

Question 4

What are C fibers?

Answer 4

C fibers are thin and nonmyelinated nerves that transmit stimuli more slowly (less than 1 m/s) than A fibers.
They constitute most nociceptors.
They respond to strong mechanical, thermal, or chemical stimuli.
Moreover, there are “silent” sensory fibers that do not respond to high-intensity stimulation under normal conditions but are spontaneously activated and respond to innocuous stimuli under inflammatory conditions.

Question 5

What is Neuropathic pain?

Answer 5

Pain arising as a direct consequence of a lesion or disease affecting the somatosensory system.
Compromises the function of the nerves.

Question 6

What was the filament we used to touch the volunteer?

Answer 6

Von Frey filaments.

Question 7

What is cold stimulation mediated by?

Answer 7

Cold sensation and pain in humans are mediated by Aδ and C fibers.
It is assumed that Aδ fibers mediate cold sensations, and C fibers most likely mediate cold pain in humans.