Term
| Ions located inside & outside neurons are distributed _____ |
|
Definition
|
|
Term
| How to determine the voltage of a neuron |
|
Definition
1. sum of + and - charges on inside of neuron
2. sum of + and - charges on outside of neuron
3. voltage = sum inside - sum outside |
|
|
Term
|
Definition
| how voltage is described (voltage across the membrane) |
|
|
Term
| Can you count the exact number of charges/ions on inside versus outside? |
|
Definition
|
|
Term
| When recording the membrane potential of a neuron, how do you keep the neuron alive? |
|
Definition
| put a neuron in a fluid (saline) that mimics cerebral spinal fluid |
|
|
Term
| When recording the membrane potential of a neuron, you put a wire into _____ which goes into neuron |
|
Definition
|
|
Term
| When recording the membrane potential of a neuron, the second electrode goes in ______ |
|
Definition
|
|
Term
| When recording the membrane potential of a neuron, two electrodes feed out to voltage signal --> creates plot of _____ versus _____ |
|
Definition
|
|
Term
| resting membrane potential |
|
Definition
| -65 (varies by cell, age of the cell, etc.) |
|
|
Term
| action potential threshold |
|
Definition
| -45 (varies but this is a good estimate) |
|
|
Term
|
Definition
| the cells have a higher resting membrane potential so it takes less input to cause action potentials to fire |
|
|
Term
| Ion channels can be _____ or ______ |
|
Definition
|
|
Term
| Are most ion channels nonspecific? |
|
Definition
| no! they are selective for a specific ion |
|
|
Term
| Can ions flow through an open channel in either direction? |
|
Definition
|
|
Term
| Why, when sodium channels open, does sodium flow into the cell? |
|
Definition
| sodium is high outside & low inside |
|
|
Term
|
Definition
| balance between the diffusion force & the electrostatic potential |
|
|
Term
| Potassium is high ______ of cell |
|
Definition
|
|
Term
| equilibrium potential for potassium |
|
Definition
|
|
Term
| equilibrium potential for sodium |
|
Definition
|
|
Term
| equilibrium potential for chloride |
|
Definition
|
|
Term
| What is another name for equilibrium potential? |
|
Definition
|
|
Term
| Is membrane potential positive or negative when the cell is at rest? |
|
Definition
|
|
Term
| How is the resting membrane potential abbreviated? |
|
Definition
|
|
Term
| How does the opening of sodium & potassium channels at the same time contribute to the resting membrane potential? |
|
Definition
1. potassium wants to rest at -80
2. sodium wants to rest at +60
3. cell will rest at -65; sodium & potassium don't contribute equally! there are many more potassium channels open at rest than sodium channels |
|
|
Term
| What is the point of the Na+/K+ ATPase? |
|
Definition
| a neuron needs to keep the concentration gradients pretty close to resting potential |
|
|
Term
| Why is Na+/K+ ATPase called an exchanger pump? |
|
Definition
| pumps 3 sodium out of the cell & 2 potassium into the cell |
|
|
Term
|
Definition
|
|
Term
| When the Na+/K+ ATPase pump is open facing the inside of the cell, affinity for ______ is low & affinity for ______ is high |
|
Definition
|
|
Term
| When the Na+/K+ ATPase pump is open facing the outside of the cell, affinity for ______ is low & affinity for ______ is high |
|
Definition
|
|
Term
| ______ is also called reversal potential |
|
Definition
|
|
Term
|
Definition
| deals with intensity of ions going in/out (not the direction like equilibrium potential) |
|
|
Term
|
Definition
| there are more potassium channels (wants to be at -80) than sodium channels (wants to be at +60) |
|
|
Term
|
Definition
|
|
Term
| A positive driving force means there's an ______ on ions |
|
Definition
|
|
Term
| A negative driving force means there's an ______ on ions |
|
Definition
|
|
Term
| For potassium & sodium, is there a positive or negative correlation between driving force & Vm? |
|
Definition
|
|
Term
| Why are voltage-gated ion channels specific? |
|
Definition
| as the ion moves through, it has to fit into little binding sites down the channel (specific to that ion!) |
|
|
Term
|
Definition
| probability of a channel opening is dependent on membrane potential |
|
|
Term
| Membrane is made up of ______ |
|
Definition
|
|
Term
| Each ion channel domain has _____ alpha helices (very well conserved) |
|
Definition
|
|
Term
| Is the structure of voltage-gated ion channels always the same? |
|
Definition
| no! sometimes it's one protein attaching to itself, sometimes it's a bunch of proteins attaching together |
|
|
Term
| For voltage-gated ion channels, molecules change their shape to move ions through in response to _____ |
|
Definition
|
|
Term
|
Definition
| voltage sensor inside the voltage-gated ion channel --> conformational change of the gate |
|
|
Term
| What do voltage-gated ion channels look like from the top? |
|
Definition
| four components with the channel in the middle |
|
|
Term
| S4 helices' positions are determined at rest by the fact that the inside of the cell is more ______ than the outside |
|
Definition
|
|
Term
| If there is a voltage change & the outside of the cell becomes more negative, what happens to the S4 helices? |
|
Definition
| they move up & out --> open channel |
|
|
Term
| Can a gate be partially open? |
|
Definition
| no! gate is always either opened or closed...there is no in between |
|
|
Term
|
Definition
| not all of the channels in a population are opened at the same time |
|
|
Term
|
Definition
| showing how membrane potential influences fractional activation |
|
|
Term
| describe sodium's activation curve |
|
Definition
~nominally 0 fractional activation at -80 membrane potential
~nominally 1 fractional activation at +40 membrane potential
~steep change (increase) between -40 and 0 |
|
|
Term
| Does potassium's activation curve look about the same as or drastically different from sodium channels? |
|
Definition
|
|
Term
| Why does increase of voltage --> increasing fractional activation? |
|
Definition
| increase of voltage is increasing the chance that all four S4 move up & out to open the channel --> increasing the fractional activation |
|
|
Term
|
Definition
| showing the influence of membrane potential on driving force |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| equilibrium potential for that ion |
|
|
Term
| electrophysiological recordings of ionic currents at specific voltages |
|
Definition
| changing the membrane potential across a certain amount of time & looking at how the current of the membrane changes along that same time plot as a result of the membrane potential change |
|
|
