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Neurophysiology Key Concepts
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Neurophysiology Key Concepts
Neurophysiology Key Concepts
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1
Question
What is the primary role of microglia in the CNS?
Answer
Immune scavenger cells that remove debris from injury or disease.
2
Question
Which glial cell type forms the myelin sheath in the CNS?
Answer
Oligodendrocytes.
3
Question
What is gliosis and its typical cause?
Answer
Proliferation of glial cells in response to brain damage.
4
Question
What cell type in the PNS forms the myelin around a single neuron?
Answer
Schwann cells.
5
Question
Which glial cells are involved in maintaining ion and neurotransmitter concentrations?
Answer
Astrocytes.
6
Question
What is the functional significance of the nodes of Ranvier?
Answer
Allow saltatory conduction, speeding nerve impulse propagation.
7
Question
In a myelinated axon, where do action potentials jump?
Answer
Between the nodes of Ranvier.
8
Question
What distinguishes multipolar neurons from other neuron types?
Answer
Multiple dendrites and one axon.
9
Question
Where does the action potential typically originate in a neuron?
Answer
At the axon hillock.
10
Question
What is the all-or-none principle in nerve action potentials?
Answer
An impulse is either fully triggered or not at all.
11
Question
How does increasing external K+ concentration affect the resting membrane potential?
Answer
It makes it less negative.
12
Question
Which ion primarily determines the resting membrane potential?
Answer
Potassium (K+), via leak channels.
13
Question
What is the effect of the Na+-K+ ATPase pump on the cell's resting potential?
Answer
Maintains the negative resting potential by pumping out Na+ and in K+.
14
Question
What triggers the opening of voltage-gated Na+ channels during depolarization?
Answer
Reaching the threshold potential (about -55 mV).
15
Question
What occurs during repolarization of an action potential?
Answer
K+ channels open, K+ exits, restoring negative potential.
16
Question
What is hyperpolarization in the context of an action potential?
Answer
Membrane potential becomes more negative than resting level.
17
Question
What is the function of astrocytes in the blood-brain barrier?
Answer
Support tight junction formation to regulate blood flow.
18
Question
What does the Nernst equation calculate?
Answer
The equilibrium potential for an ion.
19
Question
Why are unmyelinated fibers slower in conduction than myelinated?
Answer
Lack of saltatory conduction at nodes of Ranvier.
20
Question
What does a decrease in membrane potential (more negative) represent?
Answer
Hyperpolarization.
21
Question
Which ion is mainly responsible for the depolarization phase of an action potential?
Answer
Sodium (Na+).
22
Question
What triggers the initiation of an action potential?
Answer
Membrane potential reaches -55 mV, causing depolarization.
23
Question
What does the overshoot in an action potential indicate?
Answer
Membrane potential surpasses 0 mV, becoming positive.
24
Question
What is the primary role of the Na+-K+ pump after an action potential?
Answer
Reestablishes ionic gradients by active transport of Na+ out and K+ in.
25
Question
During the absolute refractory period, why can't a new action potential occur?
Answer
Most Na+ channels are inactivated and cannot reopen.
26
Question
How does saltatory conduction speed up nerve impulse transmission?
Answer
Action potential jumps between Nodes of Ranvier, skipping myelinated segments.
27
Question
What is the main difference between orthograde and retrograde axonal transport?
Answer
Orthograde moves materials from cell body to axon; retrograde from axon to cell body.
28
Question
What ion movement predominantly causes repolarization during an action potential?
Answer
K+ ions exit the cell, restoring negative membrane potential.
29
Question
What defines the relative refractory period?
Answer
A stronger stimulus is needed to trigger a new action potential due to hyperpolarization.
30
Question
What structural feature is responsible for saltatory conduction in myelinated neurons?
Answer
Nodes of Ranvier, where ion channels are concentrated.