L9 Action Potential
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Questions and Answers

What is the primary cause of the membrane potential?

  • Electrical charges within the cell
  • Unequal distribution of ions across the cell membrane (correct)
  • Chemical reactions occurring inside the cell
  • Diffusion of ions through the cell membrane

Which of the following ions is primarily responsible for the development of the action potential?

  • Calcium (Ca2+)
  • Potassium (K+)
  • Sodium (Na+) (correct)
  • Chloride (Cl-)

What is the effect of amiodarone on the sodium channels during the action potential?

  • Amiodarone enhances the inactivation of the sodium channels (correct)
  • Amiodarone activates the sodium channels, causing further depolarization
  • Amiodarone has no effect on the sodium channels
  • Amiodarone blocks the sodium channels, preventing further depolarization

What is the main effect of changes in ion concentrations on the membrane potential?

<p>Changes in ion concentrations can lead to either depolarization or hyperpolarization, depending on the specific ions involved (C)</p> Signup and view all the answers

Which of the following is a key step in the development of the action potential?

<p>Inactivation of sodium channels (C)</p> Signup and view all the answers

What is the primary purpose of the membrane potential?

<p>To generate electrical signals for communication between cells (B)</p> Signup and view all the answers

What does the Nernst equation help determine?

<p>Membrane potential at equilibrium (A)</p> Signup and view all the answers

In which refractory period does a second action potential become impossible even with a strong stimulus?

<p>Absolute refractory period (A)</p> Signup and view all the answers

Why can a stronger stimulus elicit a second action potential during the relative refractory period?

<p>Activation gate open for sodium channels (D)</p> Signup and view all the answers

What is the role of amiodarone in preventing recurrent ventricular tachycardia?

<p>Inactivation of Na+ channels (B)</p> Signup and view all the answers

How does amiodarone impact the membrane potential in the context of ventricular tachycardia treatment?

<p>Prevents depolarization by inactivating Na+ channels (C)</p> Signup and view all the answers

Why is amiodarone specifically useful in treating ventricular tachycardia?

<p>Blocks Na+ channels to prevent rapid depolarization (B)</p> Signup and view all the answers

What is the typical range of the resting membrane potential (RMP) across the membrane of excitable cells?

<p>-10 to -100 mV (D)</p> Signup and view all the answers

Which principle explains the ionic distribution that contributes to the resting membrane potential?

<p>Gibbs-Donnan membrane equilibrium (GDME) (D)</p> Signup and view all the answers

Which ion plays a primary role in the origin of the resting membrane potential?

<p>Potassium (K⁺) (A)</p> Signup and view all the answers

What is the definition of an action potential?

<p>A brief, rapid, and transient increase in the resting membrane potential, causing the cell to become more positive inside than outside (C)</p> Signup and view all the answers

Which types of channels play a dominant role in the generation of an action potential?

<p>Voltage-gated channels (B)</p> Signup and view all the answers

What is the purpose of the Nernst equation in the context of membrane potentials?

<p>It determines the equilibrium potential for an ion (B)</p> Signup and view all the answers

Which of the following statements accurately describes the effect of amiodarone on sodium channels?

<p>It inactivates sodium channels, preventing further action potentials. (A)</p> Signup and view all the answers

What is the primary mechanism by which amiodarone reduces the risk of ventricular tachycardia?

<p>It prolongs the absolute refractory period. (D)</p> Signup and view all the answers

Which of the following statements illustrates the clinical relevance of basic science knowledge?

<p>Understanding action potentials helps explain the mechanism of antiarrhythmic drugs. (A)</p> Signup and view all the answers

Which of the following resources would provide the most relevant information about action potentials?

<p>ScholarRx annotation on action potentials (A)</p> Signup and view all the answers

What is the primary function of the absolute refractory period in cardiac muscle cells?

<p>To prevent the generation of multiple action potentials. (A)</p> Signup and view all the answers

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