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Questions and Answers
What is the primary ion responsible for initiating depolarization during an action potential?
Which state indicates that the membrane potential is at its most negative during an action potential process?
What is the threshold potential that must be reached to initiate an action potential?
Which of the following correctly describes repolarization during an action potential?
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What prompts the opening of sodium ion channels in a neuron during an action potential?
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What occurs immediately after sodium ion channels open and initiate depolarization?
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During which phase of an action potential does the inside of a neuron become less negative compared to resting potential?
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How are action potentials classified in terms of their occurrence?
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What is membrane potential primarily a result of?
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What is the resting membrane potential (RMP) for a neuron cell?
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Which part of the neuron is responsible for creating the neural action potential?
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Which ion concentrations are typically higher outside the neuron compared to inside?
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What characteristic is NOT associated with action potentials?
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What is the role of the sodium/potassium pump in maintaining membrane potential?
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Excitable cells, like neurons and muscles, can change membrane potential to generate signals. What is this change called?
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Which structure conducts impulses away from the soma to the axon terminal?
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What initiates the depolarization phase of an action potential?
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At what membrane potential does the peak of action potential typically occur?
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What occurs during the repolarization phase of action potential?
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What effect does hyperpolarization have on the membrane potential?
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Which statement accurately describes the role of the Na+/K+ pump?
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How does the frequency of action potentials relate to the strength of a stimulus?
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What happens to Na+ channels at the peak of an action potential?
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What is the mechanism by which an action potential propagates along a membrane?
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Study Notes
Cell Membrane Physiology Overview
- Explains structure and function of cell membranes in regulating material flow into and out of cells.
- Membrane potential is crucial for excitable cells like nerves and muscles to generate electrical signals.
Membrane Potential
- Membrane potential arises from uneven ion distribution across the cell membrane, with more positive ions outside and more negative ions inside.
- Measured in millivolts (mV), with resting membrane potential (RMP) for neurons around -70 mV.
Resting Membrane Potential (RMP)
- RMP is the stable membrane potential in excitable cells when not producing action potentials.
- Maintained by the sodium/potassium pump, preserving high sodium outside and high potassium inside.
Neuron Cell Structure
- Neuron consists of cell body (soma), dendrites (receive signals), axon hillock (initiates action potential), axon (transmits impulses), and axon terminal (connects to other cells).
Action Potential
- Characterized by a rapid change in membrane potential starting with depolarization, triggered by sodium ion channel activation.
- Repolarization follows, mediated by potassium ion channels, returning the membrane to RMP.
Phases of Action Potential
- Resting State: All sodium and potassium channels are closed.
- Threshold Potential: A triggering event causes depolarization towards -55 mV, opening some sodium channels.
- Depolarization Phase: Sodium channels open fully, leading to an influx of Na+, rapidly raising the membrane potential to +30 mV.
- Peak Action Potential: At +30 mV, sodium channels inactivate and potassium channels open, beginning repolarization.
- Repolarization Phase: K+ leaves the cell, restoring negative membrane potential.
- Hyperpolarization Phase: Excess K+ efflux temporarily makes the interior more negative than RMP, around -90 mV.
Sodium/Potassium Pump
- Na+/K+ pump actively maintains RMP by moving sodium out and potassium into the cell, utilizing ATP for energy.
Action Potential Transmission
- Action potentials do not travel; they trigger neighboring areas to generate new action potentials.
Frequency of Action Potentials
- Greater stimulus strength increases the frequency of action potentials rather than the amplitude of individual potentials, coding stimulus strength.
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Description
This quiz covers Chapter 3 of Human Anatomy and Physiology I, focusing on cell membrane physiology and action potentials. You'll explore the structure and function of the cell membrane, mechanisms of membrane transport, and the importance of membrane potential.
