Pain and Inflammation

Question 1

What is the definition of a transducer? Name a physiological example.

Answer 1

Something that translates energy from the environment into an action potential. Examples are mechanoreceptors, chemoreceptors, thermoreceptors, etc.

Question 2

In a mechanoreceptor, deformation of the cell membrane opens ___ channels. This change in membrane potential is known as the ________ ________, aka ________ _______.

Answer 2

Na+ channels open, cause a generator potential aka receptor potential.

Question 3

As stimuli intensity increases, generator potentials increase in a ________ relationship.

Answer 3

logarithmic

Question 4

How do increasingly large generator potentials affect the action potentials in the coding region of the nerve?

Answer 4

Frequency of the APs increases.

Question 5

What does the “graded response” refer to?

Answer 5

The fact that various stimuli intensity results in variations of intensity of the corresponding generator potential.

Question 6

What is the region of the nerve called that lies between the receptor region and the coding region?

Answer 6

The spike-generating region.

Question 7

Define the following regarding adaptation:
Tonic
Phasic
Accomodation

Answer 7

Tonic: no adaptation; no change in AP frequency.
Phasic: generator potential adapts by decreasing in intensity, so the AP frequency decreases.
Accomodation: coding region membrane threshold slowly increases as a result of repetitive depolarizations and inactivation of Na+ channels. Generator potential does not adapt, though!

Question 8

Which results in a larger increase in action potential frequency:
1. Light touching on the face vs. a poke in the cheek
or
2. A medium whack with a hammer to the nose vs. a hard whack with a hammer to the nose.

Answer 8

Scenario 1 would result in a larger increase in AP frequency - the relationship is inversely logarithmic.

Question 9

What are the three sources of pain signals?

Answer 9

Superficial (body surfaces), deep (muscles, joints, connective tissue), visceral (organs)

Question 10

What is the fancy word for pain receptor?

Answer 10

Nociceptor

Question 11

Do nociceptors have a higher threshold than other sensory receptors?

Answer 11

Yeah

Question 12

What are the two nerve fibers involved in conducting superficial pain signals?

Answer 12

A-delta fibers quickly conduct initial pain signals, and the C fibers (slow conducting) mediate delayed pain signals.

-biphasic

Question 13

Are C fibers myelinated?

Answer 13

Nope

Question 14

What is hyperalgesia? What is the difference between primary and secondary hyperalgesia?

Answer 14

It is the tendency for inflamed tissues to have a reduced threshold for pain. Primary is local, damaged tissues that are sensitive to pain. Secondary is when the surrounding tissues also become sensitive.

Question 15

Damaged tissues release inflammatory chemicals like bradykinin, prostaglandins, and substance P. Can these substances stimulate nociceptors?

Answer 15

Yeah

Question 16

By what mechanism does a gentle massage help reduce superficial pain?

Answer 16

The massage stimulates an inhibitory interneuron to “gate” the transmission of the nociceptive info to the CNS.

Question 17

How can the higher centers in the brain “gate” pain signals?

Answer 17

Higher centers may send an efferent signal to interrupt the afferent pain signal at the spinal level.

Question 18

Endorophins, often released during exercise, can bind to ______ receptors in the brain.

Answer 18

opioid

Question 19

Why are certain visceral pain signals sometimes referred to other parts of the body? What is this phenomena called (fancy term)?

Answer 19

Nociceptive fibers converge with common secondary afferent neurons at the spinal level, so signals from the secondary neuron may be interpreted as originating from a different part of the body - the dermatone. This is called visceral somatic convergence.

Question 20

When does ectopic nerve disharge occur?

Answer 20

It happens when a nerve is injured (cut).