5.1.3: Neuronal Communication Flashcards
What is resting potential?
The difference between the electrical charge inside and outside of the neurone when it is not conducting an impulse, typically around -70mV.
What ions are more abundant outside the neurone compared to inside?
Na+ and K+ ions.
How is resting potential maintained?
By a sodium-potassium pump that moves 2 K+ ions in and 3 Na+ ions out.
What is the voltage of resting potential?
-70mV.
What happens during an action potential?
The neurone’s voltage increases beyond resting potential, generating a nervous impulse.
What causes depolarization during an action potential?
The neurone membrane becomes more permeable to Na+.
What is the threshold voltage for initiating an action potential?
+40mV.
What occurs when the threshold of +40mV is reached?
Voltage-gated sodium channels close and voltage-gated potassium channels open.
What is hyperpolarization?
A temporary state where the axon becomes more negative than -70mV after repolarization.
What is the refractory period?
A phase after action potential generation when the membrane cannot be stimulated.
What is the significance of the refractory period?
- Ensures discrete impulses are produced
- Ensures action potentials travel in one direction
- Limits the number of impulse transmissions.
What is the all-or-nothing principle?
If depolarization does not exceed -55mV, an action potential is not produced; all action potentials peak at the same maximum voltage.
What happens when a stimulus triggers depolarization to -55mV?
An action potential is produced.
What is the role of larger stimuli in neuronal communication?
They increase the frequency of action potentials rather than their maximum voltage.
True or False: An action potential can be generated immediately after another one.
False.
What is the effect of the sodium-potassium pump on ion distribution?
It creates an electrochemical gradient by moving Na+ out and K+ in.
Fill in the blank: The inside of the neurone is more _______ compared to the outside at resting potential.
negative.
