Which of the following characteristics determines when the refractory period ends?
answer
How long it takes for the voltage-gated Na+ channels to reactive at the end of an action potential
question
Which statement correctly describes what causes the second voltage-gated Ma+ channel to open?
answer
After the first channel opens, the movement of many types of ions (both inside and outside the cell) alters the distribution of charges near the second channel, causing it to open
question
Ions move in the direction opposite to that favored by the chemical concentration gradient when______.
answer
They are pumped by proteins that require ATP hydrolysis and when the electrical charge gradient repulses or attracts them
question
Choose the set that includes the most charged compounds that are more abundant inside neurons, in the cytosol, than outside the neurons, in the extracellular fluid.
answer
Potassium ions and proteins
question
The simultaneous arrival of graded depolarization and a graded hyperpolarization of equal but opposite magnitude at a particular membrane is likely to______.
answer
Cancel each other out, making it appear as if there was no change in membrane potential
question
In a neuron, during the depolarization phase that may trigger an action potential______.
answer
Some voltage-gated sodium channels are open
question
Of these choices, neuronal communication between the brain and the muscles of the leg is best conceptualized as______.
answer
Electrical and chemical signaling
question
The plasma membrane of a neuron has voltage-gated sodium and potassium channels. What is the effect of membrane depolarization on these channels?
answer
Membrane depolarization first opens sodium channels and then opens potassium channels
question
If the membrane potential of a neuron decreases, the membrane potential______.
answer
Becomes less negative
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