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MCAT Chemical and Physical Foundations of Biological Systems Flashcards: 4c Electrical Signaling Neurons

Study 4c Electrical Signaling Neurons in MCAT Chemical and Physical Foundations of Biological Systems with focused flashcards that help you recognize the idea, recall the key rule, and apply it in practice-style prompts.

QUESTION

During the rising phase of an action potential, which voltage-gated channel opens first?

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ANSWER

Voltage-gated Na+\text{Na}^+ channels. These channels activate at threshold, allowing rapid sodium influx that drives the membrane potential toward the sodium equilibrium potential.

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MCAT Chemical and Physical Foundations of Biological Systems: Foundational Concepts

You are hereElectrical Signaling in Neurons (4C)25 cards

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What this deck covers

This deck focuses on 4c Electrical Signaling Neurons, giving you a quick way to review the definitions, rules, and examples that matter most for MCAT Chemical and Physical Foundations of Biological Systems.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Practice questions

1 of 50Practice questions for this set
In a focused experiment on action potential propagation, a single myelinated motor neuron is stimulated at the axon hillock. Resting membrane potential is Vm=−70 mVV_m=-70\ \text{mV} and threshold is −55 mV-55\ \text{mV}. Voltage-gated Na+^+ channels open rapidly when threshold is reached, and voltage-gated K+^+ channels open with a delay to repolarize the membrane. The axon is partially demyelinated over a 2-mm segment, increasing membrane capacitance in that segment from Cm=1.0 μF/cm2C_m=1.0\ \mu\text{F}/\text{cm}^2 to 2.5 μF/cm22.5\ \mu\text{F}/\text{cm}^2 while leaving ion channel densities unchanged. Assume intracellular and extracellular ion concentrations remain constant during a single spike and that the neuron is otherwise healthy. Which outcome is most consistent with the effect of the demyelinated segment on action potential propagation along the axon?
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