Please I need help understanding this question, I'm not sure if I'm understanding it right. **Overview of the Cardiac Action Potential (A.P.) Phases**This diagram represents the action potential (A.P.) of cardiac muscle, highlighting five distinct phases: Phase 0, Phase 1, Phase 2, Phase 3, and Phase 4.**Detailed Description of Graph:**- **Phase 0:** This is the rapid depolarization phase, characterized by a sharp upward spike. It represents the opening of sodium channels and the influx of sodium ions.- **Phase 1:** Following the peak of Phase 0, there is a slight downward slope indicating partial repolarization. This is due to the closing of sodium channels and the opening of potassium channels.- **Phase 2:** This phase is more plateaued, indicating a period where the influx of calcium ions through calcium channels counterbalances the efflux of potassium ions.- **Phase 3:** Represents the rapid repolarization phase, shown by a steep downward slope. This phase is due to increased membrane permeability to potassium ions, allowing more potassium to exit the cell. **(This is highlighted in the multiple-choice question as the correct answer.)**- **Phase 4:** This is the resting membrane potential phase, depicted by a return to baseline, where ionic concentrations are restored to maintain readiness for the next action potential.**Multiple-Choice Question:**The question asks: "Phase 3 is due to:"- Movement of fewer sodium ions across the cell membrane.- **Increased membrane permeability to potassium ions.** (Correct Answer)- Calcium channels remaining open.- Increased membrane permeability to sodium ions.- Decrease in the amount of calcium diffusing across the membrane.The correct answer is the increased membrane permeability to potassium ions, which leads to a significant outflow of potassium, thus contributing to rapid repolarization.

Answered: Phase 1 Phase 2 Phase 3 Phase 0 Phase 4

Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...

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Please I need help understanding this question, I'm not sure if I'm understanding it right.

**Overview of the Cardiac Action Potential (A.P.) Phases**

This diagram represents the action potential (A.P.) of cardiac muscle, highlighting five distinct phases: Phase 0, Phase 1, Phase 2, Phase 3, and Phase 4.

**Detailed Description of Graph:**

- **Phase 0:** This is the rapid depolarization phase, characterized by a sharp upward spike. It represents the opening of sodium channels and the influx of sodium ions.

- **Phase 1:** Following the peak of Phase 0, there is a slight downward slope indicating partial repolarization. This is due to the closing of sodium channels and the opening of potassium channels.

- **Phase 2:** This phase is more plateaued, indicating a period where the influx of calcium ions through calcium channels counterbalances the efflux of potassium ions.

- **Phase 3:** Represents the rapid repolarization phase, shown by a steep downward slope. This phase is due to increased membrane permeability to potassium ions, allowing more potassium to exit the cell. **(This is highlighted in the multiple-choice question as the correct answer.)**

- **Phase 4:** This is the resting membrane potential phase, depicted by a return to baseline, where ionic concentrations are restored to maintain readiness for the next action potential.

**Multiple-Choice Question:**

The question asks: "Phase 3 is due to:"

- Movement of fewer sodium ions across the cell membrane.
- **Increased membrane permeability to potassium ions.** (Correct Answer)
- Calcium channels remaining open.
- Increased membrane permeability to sodium ions.
- Decrease in the amount of calcium diffusing across the membrane.

The correct answer is the increased membrane permeability to potassium ions, which leads to a significant outflow of potassium, thus contributing to rapid repolarization.

Expert Solution

Step 1

Action potential is a brief change in voltage across the cell membrane in a the heart cells. This change in heart potential is due to movement of atoms which re charged between inside and outside of the cell. This movement happens across protein channels which are also called as ion channels.