C13 10-11

Question 1

Phasic receptors

Answer 1

Detect a new stimulus or change in prev stimulus, but over time, sensitivity decreases - can undergo adaptation.

Question 2

Tonic receptors

Answer 2

Continuously respond to stimuli at a constant rate. i.e. proprioceptors will report position constantly. Receptors related to well being.

Question 3

Pain receptor details

Answer 3

Specialized receptors that respond to pain (nociceptors.)
Structure: simplest nerves and receptors (free dendritic endings, unipolar)
First order sensory neuron.
Generate a generator potential - fires not far from dendrites.

Question 4

Pain receptors are stimulated by:

Answer 4

Bradykinin (most common), prostaglandins, histamine, K+, ATP. Also extreme temp and mechanical damage.

Question 5

Pain neurotransmitters?

Answer 5

Substance P, glutamate

Question 6

Reduction of pain?

Answer 6

Release of endorphins/enkephalins from limbic/hypothalamus/reticular formation. Bind to presynaptic membrane and prevent release of substance p.

Question 7

Fast vs. slow pain

Answer 7

Fast: Happens first, A fibers, bright/sharp, mechanoreceptors/nociceptors, phasic/adapt quickly, localized. Slow: Happens 2nd, C fiber, dull/aching, polymodal (temp, pressure, lots of things), Tonic, diffuse

Question 8

What carries pain sensations up the spine?

Answer 8

Lateral spinothalamic tract.

Question 9

Phantom limb?

Answer 9

Cell bodies of the sensory neurons that provided sensation to the limb remain alive. Example of hyperalgesia.

Question 10

Referred pain?

Answer 10

Localized incorrectly - neurons conduct visceral pain on same tracts as somatic. Pain felt on body surface instead of viscera.