Exam 3 Lecture 3 Flashcards
Crossed Extensor Reflex: How does it Work? Right Side: Painful limb
Withdrawal affected limb by contracting the flexor muscle group [hamstring] and relaxing the extensor group [quad]
What are the 4 Reflex Pathways?
Stretch [stretch sensors], Tendon [stretch sensors], Withdrawal/Flexor [response to pain], Crossed-Extensor[response to pain]
Tension Reflex: How many interneurons are used? What are they? How do they work
2; excitatory and inhibitory
Excitatory - Reflex activation of the antagonistic muscle effect
Inhibitory - Inhibit activity in motor neuron
Does the grey matter have myelinated fibers?
Yes, not enough to make white
Compared to other Reflexes, what reflex uses the most interneurons?
The Crossed Extensor Reflex uses the most interneurons
How do COX-2 and PG’s work in the Nociceptor and 2nd order neuron
More pain = more #’s of COX-2; produces PG’s which increase sensitivity to pain by increasing sensitivity to AP; Bind to PG-R’s
Another name for Enkephalin Opiate Receptors
Mu
Flexor/Withdrawal Reflex: How does it work
Slam foot into nail - activation of flexor muscle [hamstring], flex and pull leg away from pain; Antagonistic Muscle [extensor/relax quad]
Slow Pain Pathway
C-Fiber Unmyelinated - Lamina 2, 3, 5 - AWC - Anterior Ascending Spinothalamic Tract - Brainstem - Thalamus [terminate in reticular formations in brainstem usually]
Stretch Reflex: What is a stretch receptor?
Muscle Spindle [spring in muscle]
Stretch Reflex: How it works
Push someone backwards, Quads would contract [extensor muscle] and Hamstrings would relax [antagonistic muscle, inhibitory connection, flexion muscle]
What is an A2-R and how does it operate
On nociceptor and 2nd order neuron; increases cell wall permeability to K+, make the cell more (-); shuts down nociceptor and 2nd order neuron
nACh-R: Where are Fetal channels located and why is this bad for Sux
@ NMJ and other parts of skeletal muscle [expressed by CNS when it sense something is wrong with the muscle/body] - Massive K+ hemorrhage due to increased nACh-R and them staying open longer
nACh-R: Low Conductance Immature/Fetal Channel: Total Domains, Names, Binding Domains
5 Domains; A, A1, B1, Delta, Gamma [in between A, A1 - takes place of Epsilon]
How does the sensory talk to the motor portion of the Reflex Pathways?
Direct connection between dorsal and ventral horn; OR Interneurons to cross-talk
Flexor/Withdrawal Reflex: How far superior and inferior do the signals go?
2 vertebra above and 2 vertebra below
How do Volatile Anesthetics work on the Nociceptor/2nd order neuron
Suppress CNS by increasing K+ permeability
How do Mg++ supplements help with pain?
Block NDMA; not absorbed easily = diarrhea
Does the Stretch Reflex need an Interneuron?
No; actually uses the least amount
Tendon Reflex: Goal
Make sure intense amount of tension does not pull our muscles out of their insertion points
What is INOS? What is it’s function in the nociceptor/2nd order neuron
Nitric Oxide synthase; At synapse, increases sensitivity to painful stimuli [less known than PG’s]
Tension Reflex: How is it able to be worked around?
no clear answer; will not be activated when lifting a 5000 lb car off a kitten
Crossed Extensor Reflex: Does this reflex use interneurons? If so, which ones?
Yes; ones for cross talk and ascending/descending interneurons
Flexor/Withdrawal Reflex: Where are the ascending/descending interneurons located? What is the name of this location
Posterior part of the dorsal horn between the horn and the border of the cord; this WHITE space is called the Tract of Lissaur
What does the muscle need to work properly, per lecture?
Contraction and Flexion
Fast Pain Pathway
A-Delta Myelinated - Lamina 1 - AWC - Lateral Spinothalamic Tract - Ventrobasal Complex - PL [similar to DCML]
nACh-R: Why are the Mature/Adult channels known as “High-Conductance”
When open, ions move fast through the channel; they stay open a short period of time
Drugs that bind to A2-R, least to most specific
Xylazine [tranq], Clonidine, Precedex [highest]
nACh-R: Why are the immature/fetal channels known as “Low-Conductance”
When open, ions move slower through the channel; they stay open longer than Mature channels
Are reflexes one or both sides of the body?
Can be both
Stretch Reflex: Goal?
Keep muscles a constant length, SUPPORT, Keep posture constant
Another name for the 2nd Order Descending Neuron
Serotonergic Neuron
Flexor/Withdrawal Reflex: Does it involve interneurons? Which kinds
Yes; ascending and descending to get multiple parts of the cord involved
nACh-R High Conductance Mature/Adult Channel: Total Domains, Names, Binding Domains
5 total; A, A1, B1, Delta, Epsilon [between A, A1]
nACh-R: A7 for Depolarization: Total domains, Name
7; All Alpha domains [all for binding]
Tension Reflex: How does it sense tension?
With golgi tendon sensors imbedded within tendons
Tension Reflex: How Does it work?
Increased Tension in Quad = Inhibitory IN would stop flexion in quad and excitatory IN would contract hamstring
Where is the 3rd descending neuron [Enkephalin] located?
Cell body outside dorsal horn with extension protruding in the dorsal horn grey matter
How can the 4 Reflex Pathways be inhibited?
Spinal blocks/ meds
Stretch Reflex: Clinical Testing
Tap on ligament inferior to Patella, patella drops down, foot moves forward, quad contracts
Crossed Extensor Reflex: How does it work? Left side: Non-Painful Limb
Plant left leg and contract extensor muscles in Left leg [quads]; Relax antagonistic muscle set/Flexor in this case [Hamstrings]
Crossed Extensor Reflex: Which side of the cord is used? When is this reflex important to use?
both sides of the cord are used; important when in motion/moving around
What is an Opiate-R and how does it operate?
GPCR on nociceptor and 2nd order neuron; increases cell wall permeability to K+; making the cell more (-)
Flexor/Withdrawal Reflex: Goal
want to withdrawal limbs from painful stimuli to prevent injury
