Pain Anesthesia Analgesia Flashcards
Pain
an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
any pain of moderate or higher intensity is accompanied by (2)
anxiety and the urge to escape or terminate the feeling
Nociception
the unconscious activity induced by a harmful stimulus applied to sense receptors
Noxious Stimuli
harmful, poisonous or very unpleasant stimuli
Hyperalgesia
an exaggerated response to a noxious stimulus
Allodynia
a sensation of pain in response to a normally innocuous stimulus
example of Allodynia
the painful sensation from a warm shower when the skin is damaged by burns including sunburn
Sensitization
when intense, repeated, or prolonged stimuli are applied to damaged or inflamed tissues, the threshold for activating primary afferent nociceptors is lowered, and the frequency of firing is higher for all stimulus intensities
inflammatory mediators such as (4) contribute to this sensitization
bradykinin (BK),
nerve-growth factor (NGF),
some prostaglandins (PGs), and
leukotrienes (LTs)
(2) signify increased sensitivity of nociceptive afferent fibers and hence, nociception
hyperalgesia and allodynia
Analgesia
the inability or reduced ability to feel pain without loss of consciousness or other sensations
Analgesics
substances that reduce the ability to feel pain
examples of Analgesics (4)
non-steroidal anti-inflammatory drugs,
acetaminophen,
aspirin,
opioids
Anesthesia
insensitivity to pain
Anesthetics
substances that produce a general insensitivity to pain
General Anesthetics
depress the CNS to a sufficient degree to permit the performance of surgery and unpleasant procedures
examples of General Anesthetics (4)
isoflurane,
halothane,
nitrous oxide,
propofol
Local Anesthetics
substance that when in contact with a nerve trunk can
cause both sensory and motor paralysis in the area
innervated
examples of Local Anesthetics (3)
cocaine,
lidocaine,
bupivacaine
Mechanoreceptors (2)
mediate…
respond to…
mediate responses to touch and pressure
mechanical nociceptors respond to strong pressure (e.g. from a sharp object)
Thermoreceptors (2)
detect…
activated by…
detect the sensations of warmth and cold
thermal nociceptors are activated by skin temperatures above 45°C or by severe cold (<20°C)
Chemoreceptors (2)
stimulated by…
respond to…
stimulated by a change in the chemical composition of the local environment
chemically sensitive nociceptors respond to chemicals such as bradykinin, histamine, acidity, and environmental and chemical irritants, etc
Chemoreceptors are stimulated by a change in the chemical composition of the local environment, which include receptors for (2)
taste and smell as well as visceral receptors that are sensitive to changes in the plasma level of O2, pH, and osmolality
Receptors on Nociceptive Sensory Neurons
• variety of receptors on the endings of nociceptive sensory
nerves respond to (3)
noxious thermal, mechanical, or
chemical stimuli
Transient Receptor Potential (TRP) channels (2)
• TRPV1 receptors (the V refers to vanilloids)
• TRPA1 receptors (A, for ankyrin; protein that attaches
transmembrane receptors to internal cytoskeletal proteins)
TRPV1 receptors (the V refers to vanilloids) • activated by...
intense heat, acids, and chemicals such as
capsaicin (the active ingredient in hot peppers and an
example of a vanilloid)
TRPA1 receptors (A, for ankyrin; protein that attaches transmembrane receptors to internal cytoskeletal proteins) activated by...
activated by noxious mechanical, cold, and chemical stimuli
Acid-Sensing Ion Channel (ASIC) receptors
activated by…
may be…
pH changes within a physiologic range
may be the dominant receptors mediating acid-induced pain
Intermediate signaling molecules and receptors
• in addition to direct activation of receptors on nerve endings, some
nociceptive stimuli release intermediate molecules that then activate
receptors on the nerve ending
Adenosine Triphosphate (ATP)
• acts on purinergic receptors (e.g., P2X, an ionotropic receptor and P2Y, a
G-protein-coupled receptor)
Intermediate signaling molecules acting on G-protein-coupled
receptors (6)
- bradykinin
- histamine
- prostaglandins
- serotonin (5-hydroxytryptamine or 5HT)
- substance P
- Calcitonin Gene-Related Protein (CGRP)
Nerve Growth Factor
• acts on tyrosine receptor kinase A (TrkA) receptors
ATP signaling mechanism on ionotropic receptors is very similar to
acetylcholine (ACh)
Agonists (6)
bradykinin histamine prostaglandins serotonin (5-HT) substance P CGRP
Intermediate signaling molecules (8)
- adenosine triphosphate (ATP)
- bradykinin
- histamine
- prostaglandins
- serotonin (5-hydroxytryptamine or 5HT)
- substance P
- calcitonin gene-related protein (CGRP)
- nerve growth factor