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Flashcards in Pain and Temperature Deck (91)
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1
Q

Define Pain

A
  • An unpleasant sensory and emotional experience

- Associated with actual or potential tissue damage.

2
Q

Specificity Theory

A
  • Low and high threshold receptors in specific pathway for pain that is independent of other senses
  • Intensity of pain related to amount of tissue damage
3
Q

Patterning Theory

A
  • Somatic receptors of variable sensitivity

- Different sense organs have different levels of responsiveness to stimuli

4
Q

Gate Control Theory

A
  • Pain modulated by gate in substantia gelatinosa
  • Large myelinated A-delta fibers and small un-myelinated C-fibers respond to painful stimuli like mechanical, thermal, and chemical signals that open the “gate”.
  • Stimuli from nociceptive transmissions, such as touching vibration are larger A-Beta fibers that close the gate.
5
Q

Neuromatrix Theory

A
  • Sensory inputs to the brain produce patterns of pain
  • Illustrates Plasticity - the adaptable change in structure and function of the brain networks over time.
  • Explains phantom limb pain
6
Q

3 types of Opioid receptors? What are there endogenous ligands?

A

1) Mu (μ) – Contributes most of the signs of opioid administration - Endorphins
2) Delta (δ) - Enkephalins
3) Kappa (K) - Dynorphins

7
Q

Since each Opioid receptor is a G-protein linked receptor, explain what happens when an agonist binds the receptor?

A
  • Binding to an Opioid receptor
  • G-protein (Gi) inactivates adenylate cyclase
  • Decrease in cAMP and neuronal function.
8
Q

3 locations of Opioid Receptors?

A

1) Brain
2) Spinal Cord
3) Peripheral

9
Q

What are the effects when the following opioid sub-receptors are banded:

1) Mu-1
2) Mu-2
3) Mu-3

A

1) Mu-1 - Bradycardia and analgesia (spinal and supraspinal)
2) Mu-2 - Analgesia (spinal only), respiratory depression, constipation, physical dependence
3) Mu-3 - Immune suppression

10
Q

Edinger-Westphal Nucleus?

A

Opioid stimulation causes this nucleus to constrict the pupils (miosis).

11
Q

Organize the following opioids from most potent to least potent:

1) Sufentanil
2) Fentanyl
3) Dilaudud
4) Morphine
5) Meperidine
6) Remifentanil
7) Alfentanil

A

Sufentanil > Fentanyl > Remifentanil > Alfentanil > Hydromorphone > Morphine > Meperidine

12
Q

(T/F?) Although all the opioids cause miosis (pupil constriction) Meperidine will not cause this?

A

True (Meperidine causes mydriasis and increased HR)

13
Q

Toxidrome symptoms?

A

CPR-3H

1) Coma
2) Pinpoint Pupils
3) Respiratory Depression
4) Hypotension
5) Hypothermia
6) Hyporeflexia

14
Q

PTs with who develop tolerance to the effects of opioids will never develop tolerance to which 2 opioid effects?

A

Miosis and constipation

15
Q

What are the early and late symptoms of opioid withdrawal?

A

1) Early Symptoms - Diaphoresis, insomnia and restlessness

2) Late Symptoms - Abd cramping, nausea and vomitting

16
Q

What are the onset, peak and duration of the following opioids’ withdrawal:

1) Fentanyl and Meperidine -
2) Morphine and Heroin
3) Methadone

A

1) Fentanyl and Meperidine - Onset 2-6hrs, peak 6-12 hrs, duration 4-5 days
2) Morphine and Heroin - Onset 6-18hrs, peak 36-72 hrs, duration 7-10 days
3) Methadone - Onset 24-48hrs, peak 3-21 days, duration 6-7 weeks

17
Q

Describe the characteristics of the following peripheral nerve fibers:

1) A-beta
2) A-delta
3) C-fiber dorsal root

A

1) A-beta - Heavily myelinated, used for touch and pressure, 5-12 micrometer diameter
2) A-delta - Medium myelinated, used for fast pain, touch and pressure, 2-5 micrometer diameter
3) C-fiber dorsal root - No myelination, used for slow pain, touch and pressure, .4-1.2 micrometer diameter

18
Q

What are the 3 system necessary for pain?

A

1) Afferent Pathway - Begins in the PNS, travels to the spinal gate in the dorsal horn.
2) Interpretive Centers - Located in the brainstem, midbrain, diencephalon, and cerebral cortex.
3) Efferent Pathway - Modulates pain

19
Q

What are the four elements of Pain Processing?

A

1) Transduction
2) Transmission
3) Modulation
4) Perception

20
Q

What happens during the Transduction step of pain processing?

A
  • Tissue gets damaged by exposure to chemical, mechanical, thermal, or noxious stimuli
  • Stimuli is converted to an action potential.
21
Q

What happens during the conduction step of pain processing?

A

-Pain signals from A-delta and C-fibers in dorsal horn excite or inhibit signals to 2nd order neurons.

22
Q

What happens during the Transmission step of the pain process?

A

If pain signals from A-delta and C-fibers excite 2nd order neurons, signal proceeds to the thalamus, brainstem and cortex.

23
Q

What happens during the Perception step of the pain process?

A

-Cognitive evaluative system makes you consciously aware of the pain.

24
Q

What happens during the Modulation step of the pain process?

A

Pain is suppressed or facilitated

25
Q

Primary order of Neurons?

A

Nociceptors - Bare nerve endings in the skin, muscle, joints, arteries, and viscera that respond to chemical mechanical and thermal stimuli.

26
Q

Which part of our bodies have an abundance of nociceptors?

A

1) Renal capsule
2) Periosteum
3) Arterial walls
4) Parietal pleura
5) Peritoneum

27
Q

What are the 2 types of nociceptors?

A

1) Myelinated A-delta fiber - transmit fast, sharp and localized pain.
2) Unmyelinated C-polymodal fibers - transmit slow dull, diffuse burning and aching sensations.

28
Q

Where do fast pain neurons synapse?

A

In the dorsal horn with secondary neurons.

29
Q

What are secondary-order neurons?

A

Interneurons in the dorsal horn that function as pain gates to regulate pain transmission.

30
Q

What are third order neurons?

A

Afferent neurons in the spinothalmic tract that carry information to the sensory cortex and reticular and limbic systems to interpret pain.

31
Q

What are the characteristics of the A-Beta pain fibers?

A

1) Large sized
2) Fast speed 70m/s, (myelinated)
3) Sense mechanical touch and vibration
4) Can modulate A-delta and c-fibers

32
Q

What are the characteristics of the A-delta fibers?

A

1) Medium sized
2) Medium speed 10m/s (myelinated)
3) Sharp, localized pain signal
4) Sense mechanical, and extreme temps

33
Q

What are the characteristics of C-fibers?

A

1) Small sized
2) Slow speed 1m/s (unmyelinated)
3) Dull, diffuse pain signal
4) Sense mechanical, thermal, chemical

34
Q

White matter vs. Gray Matter

A

1) White Matter - Has afferent and efferent fibers; arranged in dorsal, lateral, and ventral columns
2) Gray Matter - Houses the cell bodies; divided into 9 laminae; Dorsal horns have I-VI = sensory; Anterior horns have VII-IX = motor.

35
Q

Spinothalmic tract vs. Posterior Dorsal Column?

A

1) Spinothalmic Tract - Pain, temperature, light and crude touch
Posterior Dorsal Columns - Proprioception (position awareness), vibration, 2-point discrimination, stereognosis (depth perception)

36
Q

Corticospinal “Pyramidal” Tracts

A
  • Controls Fine motor skills

- Originate in the motor cortex and travels down to brainstem.

37
Q

Extrapyramidal Tracts control?

A

-Controls gross automatic movements, such as walking.

38
Q

Where does the decussation (crossover) of pain occur?

A

In the Spinal cord. The 1st order neuron bring the signal to the dorsal root via the A-delta and c-fibers, and the 2nd order neuron crosses the spine and goes up to the thalamus.

39
Q

Where does the localization of pain occur?

A

Somatosensory cortex of the post central gyrus.

40
Q

Spinothalmic tract vs Thalmocortical tract?

A

1) Spinothalmic tract - 2nd order neurons that go from the spinal cord to the thalamus
2) Thalmocortical tract - 3rd order neurons that go from the thalamus to the somatosensory cortex.

41
Q

Which Lamina on the dorsal horn does the following 1st order pain fiber end on:

1) A-Beta
2) A-Delta
3) C-fiber

A

1) A-Beta - Lamina 3,4
2) A-Delta - Lamina 1,5
3) C-fiber - Lamina 1,2

42
Q

Where does the signal from the following lamina go to:

1) Lamina I
2) Lamina II
3) Lamina III, IV, V

A

1) Lamina I - Thalamus and sensory cortex
2) Lamina II - Inhibits lamina I
3) Lamina III, IV, V - Hypothalamus and Amygdala

43
Q

What type of receptors are on the postsynaptic 2nd order neurons?

A

NMDA (N-methyl-D-aspartate)

44
Q

How does N2O anesthetic work?

A

-Binds NMDA receptors and preventing the release of Mg ions, thereby blocking postsynaptic depolarization resulting in anesthesia.

45
Q

Ways to peripherally suppress 2nd order neurons?

A

1) NSAIDs - COX inhibitors (ibuprofen, aspirin, etc)
2) Local Anesthetics - Block Na+ channels (lidocaine, etc)
3) Hydrocortisone - Stimulate lipocortin-1 which blocks prostaglandins/leukotrenes from arachidonic acid
4) TENs unit or mechanical stimulation - Stimulate A-beta fibers to release GABA and glycine, inhibits glutamate preventing depolarization

46
Q

Ways to centrally suppress 2nd order neurons?

A

1) Exogenous and endogenous opioids - i.e. morphine and endorphins bind to mu receptors, which closes Ca++ channels resulting in depolarization,
2) Antidepressants such as tricyclics increase availability of serotonin and NE in descending pathway

47
Q

What are the excitatory pain neurotransmitter?

A

Glutamte, aspartate

48
Q

What are the inhibitory pain neurotransmitters?

A

Serotonin, GABA, endorphins, enkelphalins, and NE

49
Q

Direct vs. Indirect excitation of pain receptors

A

Direct Excitation - Threshold depolarization from direct stimuli
2) Indirect Excitation - Usually from mediators after tissue injury

50
Q

Define Hyperalgesia?

A

Hyperalgesia is an exaggerated pain response to a normally painful stimulus

51
Q

Define Allodynia?

A

When normally non-painful stimuli induces pain

52
Q

Which part of the brain is responsible for coordinating the descending pathway for pain?

A

The Periaqueductal gray matter (PAGM) in the midbrain, which acts via the raphe nuclei

53
Q

(T/F?) Analgesic neurons cause both presynaptic and postsynaptic inhibition?

A

True

54
Q

Which neurotransmitters are released by the descending pain pathway?

A

Endogenous opioids such as endorphins and enkephalins

55
Q

How can antidepressants such as tricyclics and gabapentin reduce chronic pain?

A

By increasing the release of endogenous opioids such as endorphins and enkephalins

56
Q

What is the Anteriolateral System? What are its three different parts?

A

The Anteriolateral System is the ascending pain pathway. Its made up of the following 3 parts:

1) Spinothalamic Tract - Perception of pain
2) Spinoreticular Tract - Attention to pain
3) Spinomesenphalic Tract - Modulation of pain

57
Q

Define Segmental Inhibition of pain?

A

Low-threshold mechanical information such as touch, vibration or pressure, that closes the pain “gate”. They are mediated by A-beta fibers.

58
Q

Which part of the gray matter in the spinal cord does the descending pathway of pain synapse onto?

A

The dorsolateral tracts

59
Q

Which spinothalamic tract carries the most nociceptive information. in other words, which one carries the information of “pain” to the brain?

A

The lateral spionothalamic tract

60
Q

Before reaching the brain, the Spinothalamic tract splits into which 2 division?

A

1) Anterior-neospinalthalamic Tract - Carries fast A-delta fibers (sharp pain)
2) Lateral-paleospinothalamic Tract - Carries slow C-fibers (dull pain)

61
Q

What are the 4 categories of CNS response to pain?

A

1) The Thalamus, cortex and post central gyrus perceive, describe and localize pain.
2) The Reticular Formation an limbic system control the emotional and affective (anxiety) response to pain.
3) The ANS increases the HR, BP and RR via the SNS
4) The motor component allows you withdraw from the noxious stimuli

62
Q

What is the pain threshold?

A

The point at which a stimulus is received as pain. It does not significantly vary among people.

63
Q

What is pain tolerance?

A

The duration of time or intensity of pain that an individual will endure before initiating overt pain responses. This varies greatly among people.

64
Q

What is Perceptual Dominance?

A

When intense pain at one location causes an increase in the pain threshold in another location. i.e. An individual with many painful sites may report only the most painful

65
Q

How do Pro-Inflammatory Mediators cause hyperalgesia? Give 3 examples.

A

By lowering the threshold for pain which sensitizes nociceptors and causes transduction to occur more easily.

1) Bradykinin
2) Prostoglandins
3) Tumor Necrosis Factor Alpha

66
Q

How do NSAIDs work to reduce pain?

A

The decrease hyperalgesia by decreasing prostaglandins.

67
Q

Differentiate between acute and chronic pain?

A
  • Acute pain - sudden onset, well-defined, transient (up to 3 months) and serves as a protective mechanism.
  • Chronic pain - develops insidiously, prolonged, not easily differentiated and serves no protective purpose.
68
Q

Clinical manifestations of Acute Pain?

A

Tachycardia, HTN, sweating, dilated pupils, increased BS levels, decreased gastric acid secretion and intestinal motility, general decrease in blood flow (sympathetic responses)

69
Q

What is referred Pain?

A

Pain in an area of the body that is distant from its point of origin. It is supplied by the same spinal segment as the actual pain site.

70
Q

Persistant and chronic pain eventually leads to what?

A

1) Physiological Adaptation - Normal pulse and BP

2) Behavioral and physiological changes - Depression, difficulty eating and sleeping.

71
Q

What are the 6 most common chronic pain conditions?

A

1) Back Pain - Most common
2) Myofascial - Second most common
3) Post-op pain - Results from cutting of sensory nerves
4) Deafferentation Pain - Such as reflex sympathetic dystrophies.
5) Hyperasthesias - Associated with strokes
6) Phantom Limb Pain

72
Q

What is Neuropathic Pain?

A

Pain associated with trauma or disease of the nerves (not the nociceptors) of the PNS or CNS

73
Q

Peripheral vs. Central Neuropathic Pain

A

1) Peripheral Neuropathic Pain - When injured nerves become hyper excitable. i.e. carpal tunnel
2) Central Neuropathic Pain - Caused by lesion or dysfunction on the brain

74
Q

How does the Hypothalamus control temperature?

A

Central thermoreceptors in the hypothalamus

75
Q

What are the 4 mechanism of heat loss?

A

1) Radiation (60%) - Warm body/cold environment
2) Convection (15-35%) - Warm body/cold air blowing on PT
3) Evaporation (20%) - From breathing or from wounds
4) Conduction (<5%) - Warm body/col OR bed

76
Q

7 Perioperative events that contribute to heat loss?

A

1) Re-calibration of the hypothalamic set point
2) Drug induced vasodilation
3) Impaired shivering
4) Core to peripheral temperature redistribution
5) Cool ambient temperature
6) Cold operating room temperature
7) Administration of room temp fluids and cold blood products

77
Q

When no attempts are made to maintain normothermia, heat follows what kind of a curve?

A

A Triphasic curve of the 3 phases of intra-op heat transfer:

1) Heat redistribution from core to periphery
2) Heat transfer > heat production
3) Heat transfer ~ heat production

78
Q

Effect of heat on the Hypothalamus?

A

Temporarily resets the hypothalamic thermostat to a new set point.

79
Q

What are the Exogenous and Endogenous pyrogens that cause a fever?

A

1) Exogenous - Endotoxins produced by pathogens

2) Endogenous - Prostoglandin, IL-1, IL-6, TNF, and interferon-y

80
Q

3 types of accidental hypethermia?

A

1) Heat Cramps - Prolonged sweating and associated sodium loss causing severe spasmodic cramps in the abdomen and extremities.
2) Heat Exhaustion - Collapse from prolonged high core or environmental temps causing dehydration and and hypotension.
3) Heat Stroke - Brain cannot tolerate temps higher than 43C (109.4F) because cardiovascular and thermoregulatory centers cease function.

81
Q

What is malignant hyperthermia?

A

A inherited muscular disorder that is precipitated by the administration of volatile anesthetics or neuromuscular blocking agents. Treatment is dantrolene.

82
Q

Side Effects of binding to the following opioid receptors:

1) Mu
2) Kappa
3) Delta

A

1) Mu - Respiratory depression, euphoria, bradycardia, pruritus, sedation, mitosis, constipation, N and V, increased billiary pressure and urinary retention.
2) Kappa - Dysphoria, anti-shivering effect, sweating
3) Delta - Do not mediate bradycardia or sedation

83
Q

Which 2 opioid side effects are most resistant to tolerance?

A

Miosis and constipation

84
Q

Only endogenous opioid that causes bradycardia?

A

endorphins

85
Q

Only endogenous opioid to cause diuresis?

A

Dynorphins (endorphins and enkephalins cause retention)

86
Q

Only endogenous endorphin to cause N anV, billiard pressure, and decreased peristalsis?

A

Endorphins

87
Q

Only endogenous opioid that does NOT affect the pupils?

A

Enkephalins (endorphins and dynorphins cause miosis)

88
Q

Activation of the Reticular Activating System by C-fibers results in what?

A

Sleeping problems

89
Q

Activation of the Limbic System by C-fibers results in what?

A

Anxiety and distress

90
Q

Where in the CNS does a person’s learned pain response come from?

A

Cerebral Cortex

91
Q

Which hormones diminish the febrile response?

A

1) AVP (Argenine Vasopressin)
2) α-MSH - Melanocyte Stimulating Hormone-alpha
3) γ-MSH - Melanocyte Stimulating Hormone-gamma
4) ACTH - Adrenocorticotropic hormone