1What is the resting potential of a neuron?
-70 mV
2What maintains the resting potential?
Sodium-potassium pumps
3What does the sodium-potassium pump do?
Moves 3 Na+ out, 2 K+ in
4Which ions are more outside at rest?
Sodium ions (Na+)
5Which ions are more inside at rest?
Potassium ions (K+)
6Why is the inside of a neuron negative?
More positive ions outside
7What is the state of sodium ion channels at rest?
Closed
8What is the state of potassium ion channels at rest?
Closed
9What causes depolarization?
Stimulus opens sodium channels
10What happens when sodium channels open?
Na+ diffuses into the neuron
11What is the threshold potential?
Around -55 mV
12What happens if the threshold is reached?
Action potential is triggered
13What happens during depolarization?
Na+ diffuses in, membrane positive
14What happens at +30 mV?
Na+ channels close, K+ open
15What happens during repolarization?
K+ diffuses out, membrane negative
16What is hyperpolarization?
Membrane potential goes below -70 mV
17How is resting potential restored?
Sodium-potassium pumps
18What is the refractory period?
Neuron cannot fire again immediately
19What is the purpose of the refractory period?
Prevents overlapping action potentials
20What is an action potential?
Rapid change in membrane potential
21What is the sequence of an action potential?
Resting → Depolarization → Repolarization
22What causes a stimulus?
Change in membrane potential
23What opens during a stimulus?
Sodium ion channels
24What happens to K+ channels during depolarization?
They remain closed
25What is the potential difference during hyperpolarization?
Less than -70 mV
26What happens during hyperpolarization?
K+ channels slow to close
27What is the result of hyperpolarization?
Potential drops below resting potential
28What resets the ion channels?
Sodium-potassium pump
29What maintains resting potential?
Sodium-potassium pump
30What happens after an action potential?
Neuron can't be excited immediately
31Why can't neurons fire immediately?
Ion channels are recovering
32What happens to sodium ion channels during hyperpolarization?
They are closed
33What is the recovery period called?
Refractory period
34What does the refractory period ensure?
Discrete action potentials
35How does the action potential travel?
As a wave of depolarization
36What causes depolarization in the next region?
Sodium diffuses sideways
37What happens in the refractory region?
Action potential can't travel back
38Why are action potentials unidirectional?
Refractory period prevents backflow
39What does the refractory period limit?
Frequency of action potentials
40What kind of impulses are created by the refractory period?
Discrete impulses
41What is the "all-or-nothing" principle?
Action potential fires if threshold met
42Does stimulus size affect voltage change?
No
43What happens if the threshold isn't reached?
No action potential is fired
44What does a bigger stimulus cause?
More frequent action potentials
45What does myelination do?
Speeds up action potential conduction
46What are myelin sheaths made of?
Schwann cells
47What are the gaps in the myelin sheath?
Nodes of Ranvier
48Where does depolarization occur?
At the nodes of Ranvier
49What is saltatory conduction?
Impulse jumps between nodes
50How does saltatory conduction affect speed?
It increases conduction speed
51What affects conduction speed besides myelination?
Axon diameter and temperature
52How does axon diameter affect speed?
Larger diameters conduct faster
53Why do larger axons conduct faster?
Less resistance to ion flow
54How does temperature affect conduction?
Higher temperatures increase speed
55Why does higher temperature increase speed?
Faster ion diffusion and enzyme activity
56What happens if temperature is too high?
Enzymes and proteins denature
57What is the maximum potential difference during depolarization?
+40 mV
58What happens to potential difference during repolarization?
Drops below resting potential
59What is the effect of stronger stimuli on action potentials?
Increase frequency, not size
60Where does the refractory period occur?
After each action potential
61What is the function of the refractory period?
Prevents overlap of impulses
62Why does the refractory period ensure unidirectionality?
Prevents backward travel of impulses