What cannot be characterized as only a response to injury?
Pain
What is a complex interaction between physical, cognitive, spiritual, emotional and environmental factors?
Pain
Gate Control Theory
you hit your thumb and then rub your thumb to decrease pain." pain transmission is modulated by a balance of impulses conducted to the spinal cord. Cells in the gray matter of the dorsal spinal cord act as a pain gate. A-Delta and C fibers open the gate.
What cells act as a pain gate?
Cells in the gray matter of the dorsal spinal cord
What fibers open the pain gate?
A-delta and C fibers, neurons that carry pain
Neuromatrix theory
Brain produces patterns of nerve impulses drawn from various inputs including genetic, psychologic and cognitive experiences. Neuromatrix patterns are generally activated by sensory inputs.
What are neuromatrix patterns generally activated by?
sensory inputs
Pain perception
Conscious awareness of pain, result of interaction of the three systems: sensory-discriminative, Affective-motivational and Cognitive-evaluative
Sensory-Discriminative pain perception
Somatosenosry cortex identifies presence, character, location and intensity of pain.
Affective-motivational pain perception
individuals emotional response to pain. Mediated through reticular formation, limbic system and brain stem
Cognitive-evaluative pain perception
can modulate pain by overlying behavior. Mediated through cerebral cortex
The lowest intensity of pain that a person can recognize. Pain in one location may increase the threshold in another
Pain threshold
The greatest intensity of pain that a person can tolerate
Pain tolerance
What is influenced by genetics, gender, culture, expectations and physical and mental health
Pain tolerance and pain threshold
What three portions of the nervous system are responsible for the sensation and perception of pain?
Afferent pathways, interpretive centers and Efferent pathways
Afferent pathways
begin with pain receptors (nociceptors), travel to spinal gate in dorsal horn, then ascend to higher centers in CNS
Interpretive centers
Located in brain stem, midbrain, diencephalon and cerebral cortex
Efferent pathways
descend from CNS back to dorsal horn of spinal cord
What, anatomically appears as free nerve endings in skin and also receives temperature info?
Nociceptors
Carries information to CNS
Axon
Nociceptor examples:
A& and C (Smallest and slowest)
A&: myelinated. Fast "Bright" Pain
C: unmyelinated. Slow "Dull" pain (ache, throb)
-Carry pain and temperature information
Pain transduction begins when....
Begins when tissue is damaged by exposure to chemical, mechanical, or noxious stimuli stimulating nociceptors.
Nociceptors
-nociceptors are chemoreceptors that detect chemicals released from damaged tissue. ex: K+, prostaglandins, leukotrienes
-Detect blood products: ex: serotonin from platelets, bradykinin from plasma
-Detect products of inflammation. ex: histamine
What does Aspirin do?
blocks prostaglandins, pain reducer
Pain transmission
conduction of pain impulses to the spinal cord, axons in spinal cord and brainstem on opposite side from where they entered. information on pain in left side of body carried in right spinothalamic tract and right brainstem.
Where is pain relayed?
thalamus
Where does information end up?
somatosensory cortex (postcentral gyrus)
Transmitters of ascending pain pathways
Glutamate, Substance P, Nitric Oxide. ALL ARE EXCITATORY.
What is the main job for the efferent pathway?
reduce pain
Transmitters of Descending (efferent) pain pathways?
serotonin, GABA, Norepi., Endogenous opioids (endorphin and enkephalin)
What acts at the same receptors as opium, heroin, morphine and other related drugs?
Endogenous opioids, ENDORPHINS AND ENKEPHALINS
Endorphins and Enkephalins?
peptide neurotransmitters made by the brainstem and released in the spinal cord. All attach to opiate receptors.
What increases endorphin/enkephalin levels?
stress, excessive physical exertion, acupuncture, sexual intercourse
What is the protective mechanism against bodily harm? Transient, usually lasting seconds to days Stimulated by the autonomic nervous system (increased heart rate, hypertension, diaphoresis, dialted pupils?)
Acute pain
Somatic pain
superficial and well-localized. Sharp, dull, aching, or throbbing
Visceral pain
pain in internal organs and linings of body cavities. Poorly localized aching, gnawing, throbbing, cramping. Pain often radiates from original site.
Referred pain: Appendix
RLQ (McBruney's point)
Referred pain: Kidneys
flank on same side
Referred pain: Gall bladder and liver
right flank, back, upper abdomen and shoulder
Referred pain: Heart
left chest and arm, sometimes neck and jaw
Chronic pain
lasting 3-6+ months or well beyond normal healing time
-does not respond to normal therapy
-dysregulation of nociception and pain modulation
-neuroimaging studies show brain atrophy leading to decreased ability to cope with pain
Common chronic pain conditions?
lower back, postoperative pain, cancer, hyperesthesias, hemiagnosia
Hyperesthesais
increased sensitivity and decreased pain threshold to tactile and painful stimuli
Hemiagnosia
you hurt, but cannot pin point where at. Loss of ability to ID source of pain on one side of body, Associated with stroke.
Chronic pain, Myofascial pain syndrome, fibromyalgia, chronic fatigue syndrome?
interrelated chronic pain syndromes, compression of trigger points causes referred pain, movement disorders, autonomic responses, treated with antidepressants, LITTLE KNOWN ABOUT THESE
Neuropathic pain
caused by a primary lesion or dysfunction in the nervous system. chronic pain characterized as burning, shooting, shock like or tingling. leads to long term changes in pain pathway
-Hyperalgesia: abnormally heightened sensitivity to pain
-Allodynia: pain
peripheral neuropathic pain
trauma or disease to one or more peripheral nerves
-Nerve entrapment: nerves that are compressed or entrapped ex: Carpel Tunnel
Diabetic neuropathy
type of chronic pain syndrome. Lack of nutrition to nerve axons damages them. Pain receptors are activated and always on.
Phantom pain
brain perceives pain in amputated limb.
Body temperature
37 C 98.6 F warmer at core (rectal) cooler at extremities (cooler)
What is the temperature control center
hypothalamus