RMP Flashcards
(17 cards)
What happens to Na+ channels at +35 mV?
They close
This marks the peak of action potential.
What opens after Na+ channels close during repolarization?
Voltage-gated K+ channels
These channels are slower to open than Na+ channels.
What is the effect of K+ efflux on the cell’s interior?
Makes the cell negative inside with respect to outside
This process is called repolarization.
What is the resting potential of a neuron?
-70 mV
This is the state when the neuron is not stimulated.
What is depolarization in neurons?
The process where the cell becomes more positive with respect to the outside
It occurs when Na+ channels open and Na+ floods into the neuron.
What is an action potential?
Transient changes in the membrane potential characterized by rapid depolarization followed by rapid repolarization
It occurs only in excitable tissues.
What characterizes graded potentials?
Amplitude varies with strength of stimulus and decreases in strength as they spread out
They can be summed to reach threshold.
What is the threshold level for an action potential?
-55 mV
This is the firing level where action potential is initiated.
What happens during the absolute refractory period?
Membrane cannot produce another action potential because Na+ channels are inactivated
This period occurs right after an action potential.
What is the difference between continuous and saltatory conduction?
Continuous conduction occurs in unmyelinated fibers; saltatory conduction occurs in myelinated fibers
Saltatory conduction is faster due to jumping between nodes.
What is hyperpolarization?
When the membrane potential falls below the resting potential of -70 mV
This can occur after an action potential.
What contributes to the resting membrane potential (RMP)?
- Presence of non-diffusible anions inside the cell
- Selective permeability of the membrane
K+ efflux plays a significant role in increasing cell negativity.
What role does the Na+/K+ pump play in RMP?
Transmits 3 Na+ ions out for every 2 K+ ions in, creating negativity inside the cell
It is an active process requiring ATP.
What is the typical RMP for a nerve cell?
-70 mV
This is the standard resting potential for neurons.
Fill in the blank: The membrane potential is due to the unequal distribution of _______.
ions
This is caused by selective permeability of the cell membrane.
True or False: Graded potentials can occur in both excitable and non-excitable tissues.
True
Graded potentials can occur in response to subthreshold stimuli.
What is the peak of the action potential?
+35 mV
This is the maximum membrane potential reached during the action potential.
