Autonomic and Chapman Points Flashcards
What is a reflex?
A relationship b/w an input stimulus to the body and an output action to either a muscle or a secretory organ
What is a myotatic reflex?
Tonic contraction of the muscles in response to a stretching force due to stimulation of muscle receptors
What fibers are in the upper layers 1-6 in the spinal cord gray matter?
Afferents from body synapse here
What fibers are located in lower layers of spinal cord gray matter?
Interneurons and motor neuron cell bodies
70-80% of interneurons receive input from what?
Both visceral and somatic efferents
Describe excitation of cortical influence
The sensitization of interneurons increases throughput and amplifies output
Results in maintaining the reflex reactions
Describe inhibition of cortical influences
Reduces the somatic and autonomic outflows
What is the facilitated segment?
Constant afferent barrage by injured somatic or visceral structures would lead to segmental excitation, facilitating neuronal transmission and in turn producing excessive efferent response by the segment in question
What is sensitization?
The process of increasing response of a neural pathway with repetitive stimulation
What is habituation?
Opposite of sensitization
The process of decreasing response of a neural pathway with a continuous stimulation
What is the nociception theory?
Habituation and sensitization exist together to help maintain a homeostasis b/w over reaction and under reaction to a stimulus
Current theory as to cause for the facilitation involves alteration of nociceptive input
What is facilitation?**
Maintenance of a pool of neurons in a state of subthreshold excitation
Less afferent stimulation is required to trigger the discharge of impulses
Once established can be sustained by normal CNS activity (self sustaining process)
Facilitation may be due to what?
Sustained increase in afferent input
Aberrant patterns of afferent input*
Changes within the participating neurons themselves
The neuron chemical environment
What are the steps of increasing sensitivity of neurons?
Short term excitability (sensitization)
-1-2 seconds of afferent input; excitability lasts for 90-120 seconds
Long term sensitization
-inputs of several minutes; excitability lasts for hours
Fixation
-15-40 mins of afferent input; excitability lasts for days or weeks
Permanent excitability
-2-3 weeks of afferent input; lasts forever
What is allostasis?
The response to stress in attempt to regain homeostasis
What are commonly observed effects associated with allostasis overload?
HTN, increased risk of MI, depression, anxiety, memory loss, decreased cognition, immunosuppression, autoimmune diseases
What is a somatosomatic reflex?
Localized somatic stimuli producing patterns of reflex response in (segmentally related) somatic structures
What is a somatovisceral reflex?
Localized somatic stimulation producing patterns of reflex response in (segmentally related) visceral structures
Ex: somatocardiac, somatogastric, somatoadrenal
What is a viscerosomatic reflex?
Localized visceral stimuli producing patterns of reflex response in segmentally related somatic structures
Somatic pain referred due to visceral nociceptive stimuli (ex. Cardiac visceral pain in the chest wall)
What is a viscerovisceral reflex?
Localized visceral stimuli producing patterns of reflex response in segmentally related visceral structures