Pain

Question 1

Nociceptors have fibers in the ____ and ____ range.

Answer 1

• Aδ
• C

Question 2

The conduction velocity of an Aδ fiber is __-__m/s.

Answer 2

5-30 m/s

Question 3

The conduction velocity of a C fiber is __-__m/s.

Answer 3

0.5-2 m/s

Question 4

Aδ(type III) fibers are sensitive to ____________ and __________.

Answer 4

• Fast pain (Acute, sharp, or pricking pain)
• Cold

Question 5

C(type IV) fibers are sensitive to _____________ and __________.

Answer 5

• Slow pain (Chronic, burning, or aching pain)
• Warmth

Question 6

________ is an unpleasant emotional response to either real or perceived tissue damage.

Answer 6

Pain

Question 7

(Chronic/Acute) pain can be described as sharp, discrete, and short lasting. It is carried by Aδ fibers.

Answer 7

Acute

Question 8

(Chronic/Acute) pain can be described as burning and difficult to localize. It is carried by C fibers.

Answer 8

Chronic

Question 9

_____________ are free nerve endings that are sensitive to mechanical, chemical, and thermal stimuli.

Answer 9

Nociceptors

Question 10

Most unmyelinated nociceptors respond to mechanical, thermal, and chemical stimuli. Since they respond to multiple stimuli, they are referred to as ___________ receptors.

Answer 10

Polymodal

Question 11

___________ is the initial sharp pain, or “the twinge”, that is carried by Aδ fibers.

Answer 11

First pain

Question 12

___________ is the chronic pain occurring later, or “the throb”, that is carried by C fibers.

Answer 12

Second pain

Question 13

What are the two types of congenital insensitivity to pain?

Answer 13

• Indifference
• Insensitive

Question 14

(Indifference/Insensitive) is a type of congenital insensitivity to pain in which the person can perceive the stimulus, but lacks the appropriate response (ex. Pulling away or withdrawal).

Answer 14

Indifference

Question 15

(Indifference/Insensitive) is a type of congenital insensitivity to pain in which the stimulus is not perceived and the patient is unable to describe the intensity of type of pain.

Answer 15

Insensitive

Question 16

A skin injury is often followed by the triple response (pain triad) which entails:

Answer 16

• Local reddening
• Red flare
• Formation of a wheal on the skin

Question 17

Following an injury, chemical substances are released at the site of a wound that sensitize nociceptive afferent endings to have a lower threshold for activation and an increased firing frequency. What chemicals could be released at the site of an injury?

Answer 17

• Histamine
• Prostaglandins
• Serotonin
• K⁺
• Acids
• Acetylcholine
• Bradykinin
• Proteolytic enzymes

Question 18

The condition in which nociceptive fibers around a wound site are very sensitive, even to non-noxious stimuli, following a wound is referred to as ______________.

Answer 18

Primary hyperalgesia

Question 19

A phenomenon in which increased afferent input onto pain system neurons activates intracellular signaling pathways such that action potentials elicit larger synaptic potentials is known as ______________. For example, increased numbers of chemical receptors at synapses to make synaptic potentials larger and/or altered receptor dynamics such that their ion channels remain open longer.

Answer 19

Secondary hyperalgesia

Question 20

Nociceptive activation that persists may result in reorganization of the spinal cord dorsal horn. This reorganization involves increasing or decreasing levels of neurotransmitter. As a result, receptors of non-noxious stimuli, such as mechanoreceptors, may become capable of activating neurons in the spinal cord that carry pain information. This is referred to as ______________.

Answer 20

Allodynia (pain caused by stimulus that is normally not painful)

Question 21

The primary regulators of neurogenic inflammation following tissue injury are _____________ and ______________.

Answer 21

• Substance P
• Calcitonin-Gene Related Peptide (CGRP)

Question 22

(Substance P/CGRP) acts on mast cells causing degranulation and release of histamine.

Answer 22

Substance P

Question 23

(Substance P/CGRP) produces vasodilation of peripheral blood vessels.

Answer 23

Calcitonin-Gene Related Peptide (CGRP)

Question 24

Axons from the spinothalamic tract terminate in the (VPL/VPM) of the thalamus.

Answer 24

VPL

Question 25

Axons from the trigeminothalamic tract terminate in the (VPL/VPM) of the thalamus.

Answer 25

VPM

Question 26

(T/F) The periaqueductal tract is essential for pain modulation and control.

Answer 26

True.

Question 27

The periaqueductal gray tract originates in the ________ nucleus and descends in the spinal cord to terminate in the (ventral/dorsal) horn.

Answer 27

• Raphe nucleus
• Dorsal horn

Question 28

Raphe nuclei neurons may be activated by ___________ and ___________.

Answer 28

• Endogenous opioids (beta-endorphin, enkephalin, dynorphin)
• Opiate drugs

Question 29

What is gate control theory and how does it relate to pain modulation, such as shaking your hand after striking your thumb?

Answer 29

1. Smaller diameter fibers (Aδ and C) are activated during pain transmission. These smaller diameter fibers inhibit interneurons that would otherwise inhibit pain transmission.
2. Activation of larger diameter fibers, such as Aβ that conduct pressure and vibration, will excite the inhibitory interneurons. This causes a dulling of the pain sensation perceived. Hence, you shake your hand to activate Aβ fibers to relieve pain.

Question 30

Inhibitory neurotransmitters released from the dorsal horn in the spinal cord include:

Answer 30

• GABA
• Glycine
• Endogenous Opioids

Question 31

Inhibitory neurotransmitters released by pathways descending from the brain include:

Answer 31

• Serotonin
• Norepinephrine
• Endogenous Opioids

Question 32

(Substance P/CGRP/Histamine) produces plasma extravasation and edema (the wheal).

Answer 32

Histamine