Somatosensation Flashcards
A lower threshold of separation of a two- point discrimination test corresponds to a lower/higher sensitivity.
Higher
Are Merkel disks are more sensitive for smaller or larger stimuli?
Smaller, due to surround inhibition.
Name the four types of mechanoreceptors.
Merkel cells (SA1), Meissner corpuscle (RA1), Raffini Ending (SA2), Pacinian Corpuscle (RA2)
On which skin type are each of the mechanoreceptors found?
Merkel cells- glabrous and hairy
Meissner corpuscles - glabrous
Raffini ending- glabrous and hairy
Pacinian corpuscle- glabrous and hairy
Which mechanoreceptor is sensitive to movement direction?
Raffini endings
What is Trpv1 activated by?
T>43 degrees celsius and ligands such as capsaicin.
What is Trpm8 activated by?
T
How is information about the temperature encoded?
The rate of action potential depends on temperature.
What is the function of nociceptors? Where are they found?
Respond to stimuli that are potentially dangerous through initiating pain. They are found everywhere but the brain.
What is hyperalgesia and why does it occur?
Hyperalgesia is the heightened sensitivity of the area surround the burnt area. The reason for it is inflammation due to histomines, mast cell, factors P, which affect other nociceptors.
Why does referred pain occur?
When multiple pain fibres converge onto a single ascending neuron, it is impossible to determine where the pain originated.
