LAB 2 Flashcards
What’s the difference between orthodromic and antidromic?`
Orthodromic: in the direction of the reflex
antidromic: against the direction of the reflex
How does stimulus voltage change with neuron diameter?
bigger diameter –> lower threshold
What causes the H wave? What causes the M wave?
The H wave: The hoffman reflex. The pulse is felt in the 1a afferent n, which is carried to the spinal cord
M wave: direct stimulation of alpha-motor n.
What two nerves do we simultaously stimulate during this lab (in the popliteal space)?
The 1A afferent nerve and the alpha motor neuron
What five steps are involved in a reflex response?
Receptor, afferent limb, integrator, efferent limb, and effector
Why does a high voltage abolish the H-wave?
Renshaw cells inhibit the circuit if the frequency of impulses increases
What are the components of the reflex studied in lab 2?
Muscle spindle, 1a afferent neuron, spinal cord, alpha motor neuron, quads
How can the semicircular canals process acceleration?
Endolymph accelerates within the canals, which trigger hair cells. This is how the brain knows which direction we are accelerating
What’s the difference between an H and M wave? which neurons did they stimulate? Which comes first?
-M waves come first. They are caused by direct stimulation of the alpha-motor neuron
-H waves come second. They are caused by the stimulation of both the alpha-motor neuron, and the 1a afferent neuron. Takes more stimulation in order to happen
What are Renshaw cells? What do they do?
Renshaw cells glycine the synapses of motor neurons. This is to inhibit over use of muscles
Which neuron has a greater diameter? 1a afferent of alpha motor?
The 1a afferent neuron
Which had the smaller latency: H wave or M wave? How about threshold?
M wave: had a higher threshold of stimulation
H wave: had a lower threshold. Higher latency due to the added length of the pathway?
Which wave abolishes at high voltage? which wave increases with voltage? (H or M wave)
H wave: decreases as voltage increases
-antidromic activity gets to big, starts to cause extra refractory periods within the spinal nerves, and decreases voltage
M wave: increase as voltage increases
What happens to the M wave as you increase frequency? How about H wave?
M wave: No effect (doesn’t go to Renshaw cells)
H wave: gradually decreases with increased frequency due to activation of the Renshaw cells, and hyperpolarization of the spinal cells
At what time does the nystagmus fast phase go with the direction of motion? At what time does it go against?
Goes with the direction of motion on the acceleration. Goes against it on the slow down due to the inertia of the endolymph
