Flashcards in Autonomics/Chapman's Points Deck (42)
Afferents into the spinal cord gray matter synapse at what layers?
Interneurons and motorneuron cell bodies are at what spinal cord gray matter layers?
A majority of the interneurons receive input from?
BOTH visceral and somatic afferents
Do visceral and somatic afferents overlap?
Interactions with somatic _____ localize pain
Descending influences on reflexes
- Excitation amplifies output
- Inhibition reduces output
Facilitated segment concept
Constant afferent bombardment by injured somatic or visceral fibers leads to segmental excitation which produces excessive efferent response
For facilitated segment concept, the low threshold spinal reflexes represent a _____ pathway state caused by continuous bombardment of inputs
What did the facilitated segment concept researchers use to show somatic reflex changes?
Process of increasing a response of a neural pathway with repetitive stimulation
Process of decreasing a response of a neural pathway with continuous stimulation
The nociceptive theory of facilitation says that _____ and ____ exist together to maintain homeostasis
Sensitization and Habituation
Current theory as to cause for facilitation involves?
Alteration of nociceptive input
Describe the order of events for the nociceptive theory of facilitation
Once a stimulus is strong enough it travels to cord and branches
- releases peptides
- chemical soup (inflammatory cascade) spreads in tissues and cord
- Lowers threshold for nociceptors and interneurons
= Results in a larger than normal motor and autonomic output in those spinal level associated areas
Maintenance of a pool of neurons in a state of subthreshold excitation
- LESS afferent stimulation is needed to trigger discharge of impulses
What may cause facilitation?
Aberrant patterns of afferent input
Sustained increase in afferent input
Once facilitation is established, how is it maintained?
Normal CNS activity - self sustaining
Response to stress in attempt to regain homeostasis
What is the longterm neural effect of segmental facilitation?
Describe the steps to allostasis overload
Chemical soup of inflammatory mediators
Primary afferent sensitization
Hyperalgesia and prolonged response
Central sensitization of spinal cord neurons
Brainstem decreases descending inhibition
= allostasis overload
Allostasis overload can cause?
HTN, Depression, anxiety, memory loss, etc.
What are the 4 reflex types?
Somatic stimuli produces reflex response in somatic structures
- ex. withdrawal response
Somatic stimuli produces reflex response in visceral structures
Ex. of somatovisceral reflex
-- somatic stimuli (pain) causes visceral response
Somatocardiac reflex (somatovisceral)
Nociceptive pain somatic stimuli causes an increased HR and BP
Somatoadrenal reflex (somatovisceral)
Nociceptive pain somatic stimuli causes the release of catecholamines (adrenalin)
Visceral stimuli produces reflex response in somatic structures
ex. Cardiac visceral pain experienced as somatic pain
Visceral stimuli produce reflex response in visceral structures