Lecture 9 (pain)

Question 1

A-delta-fibers?

Answer 1

Medium diameter myelinated afferents that mediate acute, well-localized “first” or fast pain.

Question 2

Type 1 A-delta-fibers?

Answer 2

respond to both mechanical and chemical stimuli but have relatively high heat threshold (>50C).

Question 3

Type 2 A-delta-fibers?

Answer 3

much lower heat threshold, but a very high mechanical threshold.

Question 4

C-fibers?

Answer 4

Small diameter unmyelinated “C” fibers that convey poorly localized, “second” or slow pain. Both heat and mechanically sensitive.

Question 5

The four steps in the nociceptive process?

Answer 5

Transduction
Transmission
Perception
Modulation

Question 6

Transduction?

Answer 6

an activation of the action potential which sends it down through the nociceptor.

Question 7

Transmission?

Answer 7

primary afferent nerve fibers project to the dorsal horn of the spinal cord, which is organized into anatomically and electrophysiological distinct laminae.

Question 8

Perception?

Answer 8

Conscious experience of pain.

Question 9

Modulation?

Answer 9

Gate-control-theory or diffuse noxious inhibitory control.

Question 10

Gate-control-theory (dansk)?

Answer 10

Det input, der kommer ind fra de nociceptive og inden de rammer baghornene, kan de blive påvirket af interneuronet. Det vil hæmme, at det kommer til at gøre mindre ondt, fordi smerten/potentialet bliver svækket/mindsket.

Question 11

Diffuse noxious inhibitory control?

Answer 11

if you stimulate one point of the body, then it can decrease the pain in the actual place.

Question 12

Peripheral sensitization?

Answer 12

more commonly results from inflammation-associated changes in the chemical environment of the nerve fiber. It is what we call the primary inflammation. Prostaglandins are important. Takes place in the periphery nerve system.

Question 13

Central sensitization?

Answer 13

refers to the process through which a state of hyperexcitability is established in the central nervous system, leading to enhanced processing of nociceptive (pain) messages.

Question 14

The difference between peripheral and central sensitization

Answer 14

o Primary hyperalgesia is contributed to by sensitization of peripheral nerve endings (peripheral sensitization), whereas secondary hyperalgesia is due to changes in the spinal cord and higher brain areas (central sensitization).

Question 15

Neuropathic pain?

Answer 15

the pain seems to be due to inappropriate signaling of pain by neurons (rather than to tissue damage).

Question 16

What happens after peripheral nerve injury when pain is still felt?

Answer 16

Microglial cells surround the synapses between pain fibers and neurons in the dorsal horn of the spinal cord. These microglial cells release chemicals that make the dorsal horn neurons hyperexcitable. Nearby astrocytes also boost the effectiveness of the synapses between pain fibers and spinal cells. Thus, the dorsal horn neurons become chronically active, flooding the thalamus with action potentials signaling pain.

Question 17

What is the first key point in Moseley (2007)?

Answer 17

Pain does not provide a measure of the state of the tissues.

Question 18

What is the second key point in Moseley (2007)?

Answer 18

Pain is modulated by many factors from across somatic, psychological and social domains.

Question 19

What is the third key point in Moseley (2007)?

Answer 19

The relationship between pain and the state of the tissues becomes less predictable as pain persists.

Question 20

What is the fourth key point in Moseley (2007)?

Answer 20

Pain can be conceptualized as a conscious correlate of the implicit perception that tissue is in danger.

Question 21

Complex regional pain syndrome (CRPS)?

Answer 21

a chronic pain condition in which high levels of nerve impulses are sent to an affected site. Experts believe that CRPS occurs as a result of dysfunction in the central or peripheral nervous systems.

a debilitating condition that can occur after minor trauma, and sometimes without peripheral trauma, for example, post-stroke.

Question 22

Persistent or chronic pain syndromes can be initiated or maintained at?

Answer 22

peripheral and/or central loci.

Question 23

What happens with acute pain?

Answer 23

• The primary afferent nerve fiber detects environmental stimuli and transduces this information into the language of the nervous system, namely electrical current.

Question 24

When are voltage-gated sodium or potassium channels used in acute pain?

Answer 24

critical to the generation of action potentials that convey nociceptor signals to synapses in the dorsal horn - such as analgesic drugs.

Question 25

When are voltage-gated calcium channels used in acute pain?

Answer 25

play a key role in neurotransmitter release from central or peripheral nociceptor terminals to generate pain or neurogenic inflammation.

Question 26

What does peripheral sensitization more commonly result from?

Answer 26

inflammation-associated changes in the chemical environment of the nerve fiber.

Question 27

Common approach to reducing inflammatory pain?

Answer 27

Inhibiting the synthesis or accumulation of components of the inflammatory soup.

Question 28

Adequate stimuli?

Answer 28

the type of stimulus for which a given sensory organ is particularly adapted.

Question 29

Why does the brain recognize the different kinds of sensation as seperate and distinct?

Answer 29

because each modality sends its action potentials along separate nerve tracts.

Question 30

Receptor potentials?

Answer 30

the steps between the arrival of energy at a receptor cell and the initiation of action potentials in a nerve fiber involve local changes of membrane potential.

Question 31

The six aspects of sensory processing?

Answer 31

Coding
Adaption
Suppresion
Pathways
Receptive fields
Attention

Question 32

Which part of the brain is involved in attention?

Answer 32

Cingulate cortex

Question 33

Tonic receptors?

Answer 33

show little or no decrease in the frequency of action potentials as stimulation is maintained (little adaption).

Question 34

Phasic receptors?

Answer 34

display adaption, rapidly decreasing the frequency of action potentials when the stimulus is maintained.

Question 35

What detect stretching of the skin?

Answer 35

Ruffini’s endings

Question 36

What make us able to perceive the form of an object we touch?

Answer 36

The fast adapting Meissner’s corpuscles (blodlegemer) and the slow-adapting oval Merkel’s discs

Question 37

What is the dorsal column system?

Answer 37

the touch receptors send their axons to the spinal cord, where they enter the dorsal horn and turn upward, traveling to the brain along the spinal cord’s dorsal column of white matter.

Question 38

Which receptors in the body normally detect noxious heat?

Answer 38

TRPV1 (transient receptor potential vanilloid type 1)

Question 39

TRPM3 (transient receptor potential type M3) detects?

Answer 39

even higher temperatures than TRPV1.

Question 40

What does CMR1 (cold-menthol receptor 1) respond to and where is it found?

Answer 40

responds to cool temperatures and is found on small C fibers.

Question 41

Neuropathic pain?

Answer 41

for example, phantom limb pain. The pain seems to be due to inappropriate signaling of pain by neurons.

Question 42

What is a nociceptor?

Answer 42

A nociceptor is a sensory neuron that responds to damaging or potentially damaging stimuli by sending signals to the spinal cord and the brain.