Physio Lab Exam 2 - Neurophysiology Lab

If APs were the type of change in membrane potential measured at R2 & R4, what type of change in membrane potential was measured at R1 & R3?

EPSP

myelination

special wrapping of membrane from glia cells(neuroglia) around axon. CNS - oligodendrocytes. PNS - Schwann cells

What specific example(s) were give for each type of fiber?

A Fiber - sensory pacinian corpuscle; B Fiber - visceral sensory fiber; C fiber - olfactory sensory neuron and free nerve ending

Why were the peak values of the APs the same at R2 & R4 when you applied a strong stimulus? Explain.

AP values are always the same, the frequency is what changes based on stimulus

why was NT decreased in the presence of Mg++ and Ca++.

Both compete for the same channel

What part of the nervous system do interneurons belong to (CNS or PNS)?

CNS

When you injure yourself, you may feel a very sharp and immediate pain, which is later becomes a dull, throbbing pain. Based on your results, what can you infer about the axons of these two different types of neurons that must be involved in these two types of pain signals.

First sharp pain would be type A, heavy fiber with highly myelinated. Dull throbbing pain mostly type C

What happened to the NT release when the ECF contained both Mg++ and Ca++?

NT released decreased because Mg++ was a competitive inhibitor to Ca++, preventing Ca++ to flow into channel and activate release.

Explain why there is no NT release when Ca++ is absent from the ECF.

No Ca++ means nothing to trigger release, Ca++ is needed

What part of the nervous system do Sensory neurons belong to (CNS or PNS)?

PNS

If the axon of the interneuron was unmyelinated, would the peak value of the AP at R4 change relative to that at R2? Explain.

The peace value of the AP would not change because AP value are the same and are all or none. The frequency would be slower. Myelination only affects speed of transmission

what do you think would happen to NT release if you substituted Na+ for Ca++ in the ECF. Explain your reasoning.

There would be no NT release because Na+ would not operate the Ca++ channel

What two parameters/factors influence conduction velocity?

axon diameter and amount of delineation

postsynaptic potential

change in the membrane potential of target cell, change in resting membrane potential RMP

neurotransmitters

chemicals released by neurons

Explain why there was no response at R2, R3, & R4 when you applied a weak stimulus to R1.

didn't overcome the threshold to generate an AP, not enough depolarization to generate AP

EPSP

excitatory post synaptic potential, depolarizing synaptic potential

What is the term for the method/way the NTs are released from the vesicles?

exocytosis

A fiber

large diameter, heavily myelinated axon, sensory, pacinian corpuscle

B fiber

medium diameter, lightly myelinated axon, visceral sensory fiber

threshold

minimum depolarization value that EPSPs and IPSPs must sum to at the axon hillock for an AP to be generated. ~55mV

Explain why you think it is that you did or did not get a difference.Explain in terms of what you know about the anatomy and physiology of the nervous system.

only need to coordinate one side of the body

chemical synapse

region where NT released from one neuron and binds to a receptor on target cell or 2nd neuron

conduction velocity

speed that stimulus travels down axon; how fast AP travels down axon

Why does the stimulation intensity change the amount of NT released? (Talk about APs, Ca++, & vesicles)

the higher the intensity of stimulation the more APs generated triggering more Ca++ into terminal button come in channel, more vesicles to excytose

C fiber

thin unmyelinated fiber, axon of olfactory sensory neuron and free nerve ending

The squid uses an unmyelinated axon to carry the impulse that allows it to execute a very rapid escape response when it perceives danger. How is that kind of speed possible when the neuron carrying the "escape" message is unmyelinated?

uses a very think axon

Was there a difference between the two areas (arm & shoulder vs. thumb & index finger) in terms of reaction time?

yes, thumb and forefinger were faster