MetaNeuron Lesson 4 1. Action Potential Threshold. Vary the amplitude of "Stimulus 1". What effect does this have on the cell response (Figure 7)? What is the threshold stimulus amplitude (in uA) for initiating an action potential? The threshold stimulus is best measured by adjusting the stimulus amplitude in 0.1 µA increments until it is just large enough to initiate an action potential. Click on the "Stimulus 1 Amplitude" gray button and move the mouse while holding down the ctrl key. 2. Action Potentials and the Na+ equilibrium potential. Set "Stimulus 1 Amplitude" to 150 µA. The stimulus will evoke an action potential. Vary the "Na+ equilibrium potential". What effect does this have on the action potential? Why? 3. Action potentials and gK max. Using a "Stimulus 1 Amplitude" of 150 µA and a "Na+ equilibrium potential" of 50 mV, vary "gK max". What effect does this have on the time to action potential initiation and the width of the action potential? Why?

MetaNeuron Lesson 4 1. Action Potential Threshold. Vary the amplitude of "Stimulus 1". What effect does this have on the cell response (Figure 7)? What is the threshold stimulus amplitude (in uA) for initiating an action potential? The threshold stimulus is best measured by adjusting the stimulus amplitude in 0.1 µA increments until it is just large enough to initiate an action potential. Click on the "Stimulus 1 Amplitude" gray button and move the mouse while holding down the ctrl key. 2. Action Potentials and the Na+ equilibrium potential. Set "Stimulus 1 Amplitude" to 150 µA. The stimulus will evoke an action potential. Vary the "Na+ equilibrium potential". What effect does this have on the action potential? Why? 3. Action potentials and gK max. Using a "Stimulus 1 Amplitude" of 150 µA and a "Na+ equilibrium potential" of 50 mV, vary "gK max". What effect does this have on the time to action potential initiation and the width of the action potential? Why?

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter4: Principles Of Neural And Hormonal Communication

Section: Chapter Questions

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Osmosis

In simple words, osmosis is the slow, gradual movement of a liquid through a membrane. But there are nuances to this process. For instance, there has to be an imbalance in the distribution of solute in the liquid on either side of the membrane, which has to be semipermeable. The liquid in the region with a lower solute concentration moves to the region with a higher concentration, thereby displacing the solution in the process. The objective is to equalize the concentration of molecules on both sides of the membrane; the displacement of liquid can be viewed as a byproduct of this equalization. Since there is no energy required to carry osmosis, it is considered a passive process.

Question

MetaNeuron Lesson 4
1. Action Potential Threshold. Vary the amplitude of "Stimulus 1". What effect
does this have on the cell response (Figure 7)? What is the threshold stimulus
amplitude (in uA) for initiating an action potential? The threshold stimulus is best
measured by adjusting the stimulus amplitude in 0.1 µA increments until it is just
large enough to initiate an action potential. Click on the "Stimulus 1 Amplitude"
gray button and move the mouse while holding down the ctrl key.
2. Action Potentials and the Na+ equilibrium potential. Set "Stimulus 1
Amplitude" to 150 μA. The stimulus will evoke an action potential. Vary the "Na+
equilibrium potential". What effect does this have on the action potential? Why?
3. Action potentials and gK max. Using a "Stimulus 1 Amplitude" of 150 μA
and a "Na+ equilibrium potential" of 50 mV, vary "gK max". What effect does this
have on the time to action potential initiation and the width of the action
potential? Why?
4. Na+ channels and Action Potential Initiation. Action potentials are often
initiated at the axon hillock, where the axon leaves the cell body. The axon hillock
has a high density of Na+ channels, which lowers the threshold for initiating an
action potential. MetaNeuron can be used to measure the effect of Na+ channel
density on the threshold of action potential generation. Vary "gNa max" from 200
to 380 mS/cm2 in 20 mS/cm2 steps. (Na+ channel density is proportional to gNa
max.) For each "gNa max" value, determine the threshold stimulus amplitude (in
μA) for initiating an action potential. Plot the threshold current as a function of
gNa max. Why does the action potential threshold vary as Na+ channel density is
changed?

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Step 1: 1. Effect of Varying Stimulus Amplitude on Cell Response and Determination of Threshold Stimulus

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