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Neurophysics
Includes membrane potential, AP, & passive electrical properties of neurons
| Question | Answer |
|---|---|
| What is the equilibrium potential of sodium, potassium, and chloride, respectively? | Na: +55 mV K: -75 mV Cl: -60 mV |
| Write the Nernst Equation. | E = RT/zF * ln(Co/Ci) |
| Ionic flux consists of the sum of which two driving forces? | Chemical & electrical |
| At rest, is there a high or low concentration of K inside the cell? | High |
| What type of current is created by inward flux? | Negative |
| Is a cell at rest in equilibrium? | No, the sodium-potassium pump maintains the resting membrane potential in a steady state. |
| What type of current is generated by the sodium-potassium pump? | Outward. 3 Na ions exit for every 2 K ions that enter. |
| Under what condition does the GHK equation apply? | When Vm is not changing. |
| In the equivalent circuit model, which element of the circuit represents the cell membrane? | Capacitor |
| Which element of the cell is represented by the resistor/conductor in the equivalent circuit model? | Ion channels |
| What equation represents the electrochemical driving force? | Vm - Ek. |
| Which characteristic of the cell is responsible for the time course of voltage change in response to a change in current? | Capacitance |
| What effect will an increase in the length constant have on the rate of decay of voltage in a neuronal process? | An increased length constant will mean slower decay. |
| If the axial resistance is increased, what is the effect on the length constant? | It decreases. |
| Write the equation for exponential decay of current in a dendrite. | V(x) = V0 e ^ (-x/lambda) |
| In the equivalent circuit model, which cellular component is represented by a battery? | The equilibrium potential of ions |
| What type of current is the movement of positive charges out of the cell? | Positive |
| Input resistance is the ratio of which measures? | Voltage to current |
| If you increased the input resistance of a cell, what would be the difference in its response to a current pulse? | The change in voltage in response to an equal current pulse would be larger after increasing Rin. |
| Cells with low input resistance are... | less excitable. |
| Why does AP initiation take place in the axon? | 1. Higher sodium channel density 2. Lower capacitance causes faster charging 3. Axonal Na+ channels activate at more negative voltages |
| What are the three types of dendritic excitability? | 1. Backpropagation of APs 2. Sodium spikes 3. Calcium spikes |
Created by:
bmardis
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