Pain & Thermoregulation Flashcards
1
Q
Mechanoreception
A
Touch
2
Q
Thermoreception
A
Temp
3
Q
Nociception
A
Pain
4
Q
Somatic senses go through what nerve fibers?
A
Afferent
5
Q
What are the 3 types of afferent nerve fibers?
A
- A-beta
- A-delta
- C fibers
6
Q
What do a-beta fibers look like?
A
Thick (less resistance) and myelinated (fast conduct)
7
Q
What do a-delta fibers look like?
A
Thin (increase resistance), myelinated (fast conduct)
8
Q
What do C fibers look like?
A
Thin (increase resistance), unmyelinated (less conduct)
9
Q
Which fibers are fast?
A
A-beta
10
Q
Which fibers are moderate?
A
A-delta
11
Q
Which fibers are slow?
A
C fibers
12
Q
APs from a-beta fibers?
A
Mechanoreceptors (non-noxious stimuli; non pain)
13
Q
APs from a-delta fibers?
A
Mechanoreceptors and nociceptor (mechanical, thermal, fast pain)
14
Q
APs from C fibers?
A
Mechanoreceptors and nociceptor (touch, flow pain, temp/chemical)
15
Q
N transmitter from a-beta fibers?
A
Glutamate
16
Q
N transmitters from a-delta fibers?
A
Glutamate
17
Q
N transmitters from C fibers?
A
Substance P (pain) and glutamate
18
Q
What mechanoreceptor/nociceptor types are rapidly adapting and lower threshold?
A
- Hair follicles
- Meissner corpuscle
- Pacinian corpuscle
19
Q
Perceptual functions of hair follicles?
A
Skin movement
20
Q
What is meissner corpuscle skin stimulus?
A
Dynamic deformation (Braille text)
21
Q
Meissner corpuscle perceptual functions?
A
Skin motion; detecting slipping objects
22
Q
Skin stimulus of pacinian corpuscle?
A
Vibration; tapping
23
Q
How deep is pacinian corpuscle in the skin?
A
The deepest
24
Q
Perceptual functions of pacinian corpuscle?
A
Vibratory cues transmitted by body contact when grasping an object
25
Which mechanoreceptor/nociceptor types are slow adapting and low threshold?
Merkel cell-neurite complex, ruffini corpuscle, c-fiber LTM
26
Skin stimulus of merkel-cell complex?
Indentation depth (key board); form and texture
27
Perceptual functions of merkel-cell neurite complex?
Fine tactile discrimination; form and texture perception
28
Skin stimulus of ruffini corpuscle?
Stretch; hand shape and skin motion
29
Perceptual functions of ruffini corpuscle?
Skin stretch; direction of object motion, hand shape and finger position
30
Skin stimulus of C fibre LTM?
Tough (gentle)
31
Perceptual functions of C fibre LTM?
Pleasant contact; social interaction
32
What afferent response is mechano-nociceptor/polymodal nociceptor?
Slow adaption and high threshold
33
Skin stimulus for mechano-nociceptor/polymodal nociceptor?
Injurious forces; pain, temp
34
Which mechanoreceptor/nociceptor types need to have the greatest stimulus?
Mechano-nociceptor/polymodal nociceptor
35
Which mechanoreceptor/nociceptor type has the greatest receptive field?
Pacinian corpuscle
36
Receptive field of merkel cell-neurite complex?
4 smaller circles
37
Ascending neural pathway of somatosensory system for touch and pressure?
Dorsal column system (DCS)
38
2nd order fibers cross over where in touch and pressure?
From medulla to thalamus
39
What kind of fibers are in touch and pressure?
Large myelinated fibers (A-beta)
40
What kind of spatial fidelity in touch and pressure?
High degree
41
What are the 5 touch and pressure mechanoreceptors?
1. Hair follicles
2. Meissner corpuscle
3. Pacinian corpuscle
4. Merkel-cell neurite complex
5. Ruffini corpuscle
42
Ascending neural pathways of somatosensory system for pain, temp, light touch?
Anterolateral system (spinalthalmic tract(STT))
43
2nd order fibers cross where in pain, temp, and light touch?
Spinal cord
44
What do the fibers look like in pain, temp, light touch?
Smaller myelinated (a-delta) and unmyelinated (c fibers)
45
Pain, temp, light touch spatial fidelity?
Low (more loss to regions lower than thalamus)
46
What are the 2 mechanoreceptors for pain, temp, light touch?
1. C-fibre LTM
| 2. Mechano-nociceptor/polymodal nociceptor
47
What is the dorsal column system (touch and pressure) pathway?
1. Ascending branches of dorsal root fibers
2. Dorsal column nuclei at lower medulla oblongata
3. Ventrobasal complex of thalamus
4. Somatosensory cortex
48
Anterolateral system of pain, temp, light touch pathway?
1. Dorsal root and spinal ganglion
2. Cross over in spinal cord
3. Ventrobasal and intralaminar nuclei of the thalamus
4. Postcentral gyrus of cerebral cortex
49
What area can manipulate pain signals?
Spinomesencephalic tract
50
What is the postcentral gyrus in charge of?
Somatosensory
51
What is precentral gyrus in charge of?
Motor
52
What do all pain receptors look like?
Free nerve endings of unmyelinated C fibers and small diameter myelinated a-beta fibers
53
What are the 5 things that nociceptors look like?
1. Widely distributed free nerve endings
2. High threshold
3. Specific to stimulus
4. NOT adapt to stimulation
5. Correlated to rate of tissue damage
54
Increased sensitivity of free nociceptive afferent nerve endings by chemical factors associated with what?
Inflammation
55
What is pain enhancement from?
1. Prostaglandins and substance P
56
What are the pain induction?
Sleep nociceptors and awakening agents (bradykinin, serotonin, histamine, K+ ions, acids, nerve growth factor)
57
Where are pain induction most important?
Deep tissue afferents (gut, joints) as they are insensitive normally
58
What activates TRPV1 and induce depolarization of nociceptive axons via Na and Na entry
Bradykinin, substance P, and nerve growth factor
59
What opens the TTX-Resistant VGNC’s?
Prostaglandins
60
What blocks VGNC’s?
TTX (tetrodotoxin)
61
Pain: fast fiber and slow fibers
Fast: a-delta (myelinated)
Slow: C fibers (unmyelinated)
62
Pain: fast vs slow
1. Neurotransmitters
2. Speed
3. Feeling
4. Location
5. Tract
1. Fast: glutamate; slow: substance P
2. Fast: .1s; slow: 1s
3. Fast: shape, localized well; slow: dull, throbbing, aching, poor localization
4. Fast: surface, not deep in tissue; slow: seen with tissue destruction
5. Fast: neospinothalamic tract (localization); slow: paleospinothalmic tract (reticular activing system: attention, arousal)
63
What is dual pain?
A-delta fibers (fast) transmit firs pain sensation, which is felt as prickling pain of rapid onset. Later transmission by slower C fibers, results in delayed aching or burning sensation
64
Physiological painful: acute or chronic?
Acute
65
Pathological pain: acute or chronic?
Chronic
66
3 facts about physiological pain (acute)
1. Reflexive avoidance
2. Little or no tissue injury
3. Pain stops shortly after stimulus is removed
67
6 facts about pathological pain (chronic)
1. Tissue or nerve injury
2. Inflammation occurs
3. Release NTs with ongoing stimulation of nociceptors
4. CNS pathway sensitized/reorganized
5. Lead to hyperalgesia
6. Persists after stimulus is removed (refractory to NSAIDs and opioid therapy)
68
Area of skin supplies by sensory neurons that arise from a spinal nerve ganglion
Dermatome
69
What analgesics affect brain?
Opioids
| Alpha 2 adrenoceptor agonists
70
What analgesics affect dorsal horn?
Local anesthetics
Opioids
Alpha 2 adrenoceptor agonists
71
What analgesics affect peripheral nerve?
Local anesthetics
72
What analgesics affect peripheral nociceptors?
Local anesthetics
| Antiflammatory drugs
73
What is responsible for pain?
Prostaglandins produced by COX-2
74
What does corticosteroids inhibit?
Phosphorlipidase A2
75
What does NSAID inhibit?
COX 1 and 2
76
What does reduced prostaglandins do?
Reduces Na entry into nociceptors
77
What are the 2 anti inflammatory drugs?
NSAIDs and corticosteroids
78
What does local anesthetics do?
Block APs in peripheral neurons
79
What is the nonionized form of local anesthetic and what does it do?
R-NH2; penetrates the axonal membrane and is then converted to the ionized form (R-NH3+)
80
What is the ionized form and what does it do?
R-NH3+; binds to the Na channel in the open state and this prolongs the Na channel inactivation state and Na entry is blocked during inactivation sate
81
What is endogenous pain stress response?
Serotonin and beta-endorphin (opioid)
82
Where is endogenous pain stress response found and what does this do?
Found in hypothalamus and pituitary
| Simulates endogenous opiate production
83
What are the opioids?
Enkephalins and dynorphins
84
Where are the opioids found and what do they do?
Found in brain stem and spinal cord
| Pre-post synaptic inhibition of type C and a-delta
85
What is naloxone?
Opioid receptor antagonist
86
What does opiates do on the presynaptic?
- decrease peripheral AP
| - decrease distal Ca++ influx and NT release
87
What does opiates do on the Postsynaptic?
Hyper polarized due to K+ efflux
88
What does alpha 2 agonism do on the presynaptic?
Decrease distal Ca++ influx and NT release
89
What are the NMDA antagonisms?
Ketamine and magnesium
90
What do the NMDA antagonisms do on the Postsynaptic?
- allow lots of Ca++ and little Na into cell
| - decrease glutamate receptor signaling NT release
91
What can substance P do to NMDA antagonism?
Enhance NMDA opening
92
What functions as the bodies thermostat?
Hypothalamus
93
What is body temp controlled by?
Balance between heat production and heat loss
94
What provides heat transfer?
Blood flow to the skin from the body core
95
Thermoregulation afferent fibers?
A-delta and C fibers
96
What detects the fever and hyperthermia damage?
Hypothalamus
97
What are the efferent outputs for thermoregulation (4)
Temp (arteriole and sweat glands)
| Metabolism (skeletal muscle and thyroid)
98
What is the greatest mechanism of heat loss?
Radiation 60%
99
What is the least mechanism of heat loss?
Conduction to objects 3%
100
Sweating caused by stimulation of what?
Anterior hypothalamus preoptic area (AHPA)
101
Nerve impulses from AHPA lead to stimulation of what?
Cholinergic nerve fibers that innervate sweat gland
102
How does post ganglionic neuron for sweat gland innervates differs and what does it release?
Differs from other sympathetic postganglionic neurons in that it releases acetylcholine to act on muscarinic receptors (atropine fever)
103
Do adrenergic fibers innervate sweat glands usually?
No
104
Sweat glands can be stimulated by what?
Circulating Epi and NorE
105
What does the sweat gland duct absorb?
Mainly Na and Cl
106
What does the sweat gland primary secrete?
Mainly protein free filtrate
107
Increased blood and internal temp causes what kind of firing and temp at the hypothalamus?
Increase
108
What 2 things occur when the hypothalamus temp increase?
Vasodilation and sweat glands become more active increasing evaporative heat loss
109
Decreased temp causes what kind of temp and firing in hypothalamus?
Decreasing
110
What 2 things occur when hypothalamus temp and firing decrease?
Vasoconstriction and skeletal muscles shivering to increase metabolism that generates heat
111
What kind of feedback does temperature reflex have?
Negative feedback
112
Redistribution phase:
core temp decreases 1-1.5 degree during the 1st hour
113
Linear phase:
During following 3 hr core temp linearly decreases due to heat loss exceeding metabolic heat production
114
Core temp plateau:
After 3-5 hr of anesthesia core temp stops dropping
115
What are the 4 major factors for heat loss?
1. Type and dose of anesthesia
2. Amount of surgical skin exposure
3. Ambient temp
4. Duration
