Physio Psych Quiz 1.2
After the peak of an action potential, what prevents sodium ions from continuing to enter the cell?
After the peak of an action potential, what prevents sodium ions from continuing to enter the cell?
In the normal course of an action potential, ____.
In the normal course of an action potential, ____.
Voltage-activated channels are channels for which a change in the voltage across the membrane alters their ____.
Voltage-activated channels are channels for which a change in the voltage across the membrane alters their ____.
Which event will increase the concentration gradient of sodium?
increasing activity of the sodium potassium pump
Electrical gradients lead to the ____.
movement of ions to areas having opposite electrical charges
When the neuronal membrane is at rest, the sodium channels ____.
are closed, so there is almost no flow of sodium
At what point do the sodium gates begin to close, shutting out further entry of sodium into the cell?
at the peak of the action potential
Ordinarily, stimulation of a neuron takes place ____.
at the synapse
A drug that blocks the sodium gates of a neuron's membrane will ____.
block the action potential
When a membrane is at rest, what attracts sodium ions to the inside of the cell?
both an electrical gradient and a concentration gradient
The net effect of each cycle of the sodium-potassium pump is to ____.
decrease the number of positively charged ions within the cell
What occurs when a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential?
hyperpolarization
Under which conditions would the sodium-potassium pump likely be far less effective in creating a concentration gradient?
if selective permeability of the membrane did not exist
The function of a myelin sheath is to ____.
increase the velocity of transmission along an axon
Which action would depolarize a neuron?
increasing membrane permeability to sodium
The resting potential is mainly the result of ____.
negatively charged proteins inside the cell
When the neuronal membrane is at rest, the potassium leak channels ____.
permit potassium ions to pass slowly
Local anesthetic drugs attach to the sodium channels of the membrane, which ____.
prevents sodium ions from entering and stopping action potential
At the peak of the action potential, the electrical gradient of potassium ____.
pushes potassium out of the cell
The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the ____.
refractory period