Viscerosomatic and Chapman's Reflexes Flashcards
SC Gray Matter Layers
- Upper
- Lower
-Upper Layer 1,5: alpha delta fibers (fast pain) Layer 2: small c fibers (slow pain) Layer 3,4: mechanoreceptors -Lower: MN cell bodies and interneurons
Sensitization
-when stimulus repeated, response to stimulus grows until there is a stable response level
Habituation
-decrease response with a continuous stimulation
Facilitation
maintenance of pool of neurons in state of subthreshold–> less afferent stimulus required to trigger impulse
Cause of Facilitation
- stimulus strong enough to depolarize nociceptive path, impulses travel to cord and branch
- release of peptides at MN and initiate inflammation–> lowers threshold and increases input to cord
- inflammation disrupts balance between sensitization and habituation–> larger motor outputs to ANS and somatic
- no nociceptors in brain and hyaline cartilage
Steps for Increasing Sensitivity of Neurons
- ST sensitization: 1-2 sec afferent input 90-120 sec excitability
- LT sensitization: several min input, hours of excitability
- Fixation: 15-40 min input, days/weeks excitability
- Permanent Excitability: forever, death of inhibitory interneurons
Facilitated Segment Concept
low threshold spinal reflexes with hyper-excited pathways being inputted
Allostasis
primary: hyperalgesia exaggerated response
secondary hyperalgesia develops
Dorsal Horn Neurons: lose inhibitory neuron function, Ca channel opens, aids in facilitation
Ventral Horn: outflows to autonomics (visceral function) and soma (TART findings)
Brainstem: decrease endogenous descending path
Arousal system releases glucocorticoids and catecholamines, and long term facilitation damages system–> loss of protective mech
Somatosomatic Reflex
- cut finger and now protect finger because whole finger affected
- Withdrawal response to pain, myostatic reflex
Somatovisceral Reflex
- Somatocardiac: possibly more nociceptors increase HR and BP
- Somatogastric: inhibition of peristalsis
- Somatoadrenal: release of catecholamines from adrenal medulla
Viscerosomatic Reflex
- feeling on soma associate with something going inside
- ex. pain in upper back early sign of heart attack
Viscerovisceral Reflex
- gut reflex back to gut
- distention of gut–> increase gut muscle contraction
- afferents flow into SC and produces outflow to ANS MN
ENT Viscerosomatic Reflex
Head/Neck
Sympathetics
T1-T5
GI Viscerosomatic Reflex
Sympathetics -Upper GI T5-T10 -SI/Ascending Colon T9-T11 -Ascending Colon and Transverse Colon T10-T12 -Descending and Sigmoid T12-L2 Parasympathetics -Upper GI Vagus -SI/Ascending Colon Vagus -Ascending Colon and Transverse Colon Vagus -Descending and Sigmoid S2-S4
Extremities Upper/Lower Viscerosomatic Reflex
Sympathetics
Upper T2-T7
Lower T11-L2