Download L3411 Problem Set 8 1) (2 pts) Below is a diagram of an action

L3411 Problem Set 8
1) (2 pts) Below is a diagram of an action potential in a typical neuron (with typical
sodium and potassium concentrations). Match the following phrases or events with the
appropriate letter on the diagram (A-J). Each letter may only be used once.
1. _____Undershoot
2. _____Overshoot
3. _____ENA+
4. _____EK+
5. _____Threshold
6. _____Resting Potential
7. _____Absolute refractory period
8. _____Relative refractory period
9. _____Rising Phase
10. ____Falling Phase
2. Name the two strategies that have developed in nature to increase the speed of neuronal signal
propagation (1 point). Explain why these strategies work to increase the rate of nerve conduction in
terms of the length constant (1 point). Answer only in the space provided below.
3. (1 point) What accounts for the unidirectional movement of an action potential? In other words,
once an action potential has started, what prevents it from traveling backwards up the axon? (answer
in 10 words or less)
4) (2.5 pts) Match the following statements with the appropriate letter (A-G) from the figure
below.
_____ 1 Point where there is minimal driving force on K+
_____ 2 Point where there is minimal driving force on Na+
_____ 3. Potential where K+ moves into the cell
_____ 4. Potential where Na+ moves out of the cell.
_____ 5 Point where the electrical gradient does not push K+ in or out of the cell.
_____ 6. Point closest to the equilibrium potential for calcium ion.
_____ 7. Point along voltage waveform where there are fewest voltage-dependent channels
open
_____ 8. Point closest to the reversal potential for the voltage-dependent Na+ channel.
_____ 9. point where the potassium current is larger than the sodium current.
_____ 10 points where the sodium current is equal and opposite to the potassium current.
Answer the following True/False questions. Correct the statement if it is false. (2.5 points)
______ Active propagation is independent of passive propagation
______Voltage-gated Na channels are essential to generate an action potential.
______ Current is inversely proportional to resistance
______ The driving force for potassium is maximal at Ek.
______ Receptor potentials are actively propagated.
______ Myelin effectively increases both membrane resistance and membrane capacitance
______ Salatatory conduction refers to the propagation of the action potential between nodes of
Ranvier on unmyelinated axons.