Lecture 1: Viscerosomatic and Chapman's Reflexes Flashcards
What is a reflex?
Relationship between an input stimulus to body and output action in a muscle or secretory organ
What receptors are found in the upper layers 3 and 4 of the spinal cord gray matter?
Mechanoreceptors
What receptors are found in the upper layers 1 and 5 of the spinal cord gray matter?
A-δ fast pain fibers
What receptors are found in the upper layer 2 of the spinal cord gray matter?
Small c fibers of slow pain
What is found in the lower layers of the spinal cord gray matter?
Interneurons
Motorneuron cell bodies
Where do interneurons receive input from?
Visceral and somatic afferents
What is habituation?
Process of decreasing response of a neural pathway w/ a continuous stimulation
Ex: getting use to a bad smell or not feeling pain for long time
What is sensitization?
Repetitive stimuli that can lead to a growing response until stabilization
-Amplifying of sensations
What is the nociception theory?
Homeostasis between habituation and sensitization between over and under reactions to a stimulus
What is facilitation?
Maintenance of a pool of neurons in a state of sub-threshold excitation
-Less stimulation needs to happen for excitation
What is the current theory regarding nociception?
- Strong stimulus activates nociceptive pathways.
- Impulses travel to spinal and cord and branch.
- Release of peptides in motor neurons
What type of peptides are released in the nociceptive pathway?
- Inflammatory cascade and initiate release of prostaglandins. bradykinins, etc
- Lowers nociceptor thresholds
Inflammation disrupts the balance between what?
Habituation and sensitization
-larger normal motor outputs to autonomic and somatic systems
What is short term excitability?
1-2 seconds of afferent input
90-120 seconds of excitability
What is long term excitability?
Several minutes of afferent input
Hours of excitability