LECT - Chapman's Points Flashcards
What fibers do the upper layers of spinal cord gray matter contain?
A delta fast pain fibers
Small C slow pain fibers
What fibers do the lower layers of Spinal cord gray matter contain?
Efferents: interneurons, motor neuron cell bodies
What function do interneurons serve for sensory input?
Amplify or inhibit output
What effect does visceral disturbance have on somatic musculature?
Activates it => Facilitated segment => alter visceral function => decompensation of homeostasis
How long does short term excitability last?
90-120 seconds
What are the steps for increasing sensitivity of neurons?
- Sensitization (short term excitability)
- Long term sensitization
- Fixation
- Permanent excitability
What phase of increased neuron sensitization causes death of inhibitory interneurons?
Permanent excitability
Who were the scientists involved with identifying Facilitated Segments?
Denslow - 1st to associate excitable changes w/ injury and disease
Korr - Suggested that low level spinal reflex represented pathways in hyperexcited state because they were constantly bombarded w/ input
Who coined the term Facilitated Segment?
Dr. I.M. Korr
What is the Nociceptive theory of facilitated segments?
- Stimulus depolarizes nociceptive pathways =>
- Impulse travels to spinal cord (SC) =>
- Branch to multiple sites =>
- Release peptides at motorneuron level in peripheral tissues =>
- Inflammatory cascade, release of prostaglandins, bradykinins =>
- Lower nociceptor thresholds =>
- Increased input to SC =>
- Larger than normal motor output to autonomic and somatic systems =>
- Facilitated segment
What is allostasis?
The process by which the body responds to stressors in order to regain homeostasis = long-term neural effect of segmental facilitation
What is the allostatic process on facilitated segments?
Stimulus applied to tissues => release of cytokines and peptides => inflammation => primary afferent sensitization => hyperalgesia (exaggerated response to noxious stimulus) => secondary hyperalgesia
What is the dorsal horn involvement in allostasis?
Open Ca++ channels, initiate phosphorylation cascades
Lose inhibitory neuron fxn
Aid in maintaining facilitation
What is the ventral horn involvement in allostasis?
Facilitation outflow to autonomics => affect visceral fxn
Facilitation outflow to soma => muscle spasm, asymmetry, altered ROM
What is the brainstem involvement in allostasis?
Facilitation decreases endogenous descending pathways
Facilitation decreases arousal system (glucocorticoids, catecolamines) => loss of protective mechanisms => allostasis
What is the withdrawal response? What type of reflex is this?
Noxious stimulus (heat from oven) is applied to somatic structure (skin of hand)
Somatosomatic
What is the myotatic reflex? What type of reflex is this?
Stretch receptor is stimulated and stretched muscle receives impulse to fire, while antagonist is inhibited
Somatosomatic reflex
What is the somatocardiac reflex? What type of reflex is this?
Nociceptive somatic stimuli => elevated heart rate and BP
Somatovisceral
What is the somatogastric reflex? What type of reflex is this?
Nociceptive somatic stimuli => inhibition of peristalsis in stomach
Somatovisceral
What is the somatoadrenal reflex? What type of reflex is this?
Nociceptive somatic stimuli => release of catecholamines from adrenal medulla
Somatovisceral
What is the physiological basis for viscerosomatic reflexes?
Localized visceral stimuli producing patterns of reflex response in segmentally related somatic structures (e.g. Chest pain => L arm pain)
All visceral nerves contain sensory fibers, cell bodies located in DRG or vagal ganglia
There are numerous interneuron connections in DRG => complex communication network connecting visceral and somatic systems
What viscerosomatic regions are parasympathetically innervated by pelvic splanchnics?
Descending and sigmoid colon/Rectum
Bladder, lower ureter
What viscerosomatic regions are parasympathetically innervated by the vagus nerve?
Upper GI
SI/Ascending colon
Ascending and transverse colon
Heart, Lungs, Adrenals
Reproductive organs
Upper/Lower Ureter
Bladder
Sympathetic viscerosomatic reflexes: What levels are head and neck located?
T1-T5
