Multiple Choice
During an action potential, the loss of potassium ions ($K^+$) from the cell results in:
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45. Nervous System
Neurons and Action Potentials
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Saltatory conduction is made possible by ________.
A
the release of neurotransmitters at synaptic terminals
B
the influx of calcium ions into the neuron
C
the presence of myelin sheaths around axons
D
the continuous propagation of action potentials along unmyelinated fibers
Verified step by step guidance1
Understand the concept of saltatory conduction: It refers to the process by which action potentials 'jump' from one node of Ranvier to the next along a myelinated axon, rather than propagating continuously along the entire length of the axon.
Recognize the role of myelin sheaths: Myelin sheaths are insulating layers of fatty material that surround the axon. They prevent the leakage of ions and increase the speed of electrical signal transmission.
Identify the nodes of Ranvier: These are small gaps in the myelin sheath where the axon membrane is exposed. These nodes are rich in voltage-gated sodium and potassium channels, which are essential for the generation of action potentials.
Understand how saltatory conduction works: In myelinated axons, the action potential is regenerated only at the nodes of Ranvier. The electrical signal effectively 'jumps' from one node to the next, which speeds up the conduction process compared to unmyelinated axons.
Eliminate incorrect options: The release of neurotransmitters at synaptic terminals and the influx of calcium ions are processes related to synaptic transmission, not saltatory conduction. Continuous propagation of action potentials occurs in unmyelinated fibers, which is the opposite of saltatory conduction.
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