Cardiac Physiology and Action Potential
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Questions and Answers

What is represented in phase 3 of the action potential?

  • Unstable resting membrane potential
  • Repolarization (correct)
  • Depolarization
  • Stable resting membrane potential
  • Phase 0 of the action potential involves fast Na+ entry.

    True

    What causes phase 3 of the action potential?

    K+ efflux

    Phase 4 represents the ______ membrane potential.

    <p>resting</p> Signup and view all the answers

    Match the following phases with their characteristics:

    <p>Phase 0 = Fast Na+ entry Phase 3 = K+ efflux Phase 4 = Resting membrane potential Phase 2 = Slow Ca+2 entry</p> Signup and view all the answers

    What represents phase 4 of the action potential?

    <p>Stable resting membrane potential</p> Signup and view all the answers

    Phase 0 of the action potential is characterized by depolarization.

    <p>True</p> Signup and view all the answers

    What ion entry primarily causes phase 0 of the action potential?

    <p>Na+</p> Signup and view all the answers

    Phase 4 is caused by _______ efflux.

    <p>K+</p> Signup and view all the answers

    Match the action potential phases with their characteristics:

    <p>Phase 0 = Rapid depolarization due to Na+ influx Phase 4 = Stable resting membrane potential Phase 3 = Repolarization due to K+ efflux Phase 1 = Initial repolarization</p> Signup and view all the answers

    What is the phase of depolarization in an action potential commonly referred to as?

    <p>Phase 0</p> Signup and view all the answers

    Resting membrane potential is also known as 'unresting membrane potential'.

    <p>False</p> Signup and view all the answers

    What occurs during the depolarization phase of an action potential?

    <p>Sodium channels open, allowing Na+ ions to enter the cell.</p> Signup and view all the answers

    During phase 0 of an action potential, the membrane undergoes __________.

    <p>depolarization</p> Signup and view all the answers

    Match the following action potential phases with their descriptions:

    <p>Phase 0 = Rapid depolarization due to sodium influx Phase 1 = Initial repolarization Phase 2 = Plateau phase Phase 3 = Rapid repolarization due to potassium efflux</p> Signup and view all the answers

    Study Notes

    Cardiac Physiology

    • Normal Heart Rate: 70/min
    • Heart Rate During Exercise: 120-150/min
    • Cardiac Output: 5 L/min
    • Heart Muscle: Syncytium
    • Blood Flow Order: Right atria, right ventricle, lungs, left atria, left ventricle, rest of the body

    Action Potential

    • SA Node: Initiates the heartbeat. This is the pace-maker
    • Phase 0 (depolarization): Caused by rapid Na+ entry
    • Phase 4 (resting membrane potential): Unstable
    • Phase 3 (repolarization): K+ efflux
    • Phase 2 (plateau): Caused by slow Ca++ entry

    ECG Waves

    • P-wave: Atrial depolarization
    • QRS complex: Ventricular depolarization
    • T-wave: Ventricular repolarization

    Factors Affecting Cardiac Output

    • Stroke volume: Determined by preload, afterload, and contractility
    • Preload: Blood volume in ventricles before contraction
    • Afterload: Resistance to ejection of blood from ventricles
    • Contractility: Force of ventricular contraction
    • Blood volume: Influences preload
    • Venous return: Influences preload
    • Blood viscosity: Affects TPR (total peripheral resistance)

    Contractility Factors

    • Length of blood vessels
    • Viscosity of blood
    • Diameter of lumen
    • Cardiac output
    • Blood volume

    Factors Affecting Blood Pressure

    • Cardiac output
    • Blood volume
    • Viscosity

    Respiratory Physiology

    • Traps Microorganisms: Mucus, cilia, and hair

    • Keeps Trachea Open: Cilia, Cartilage rings

    • Alveoli Structure: Single layer, moist, surrounded by capillaries

    • Surfactant: Decreases surface tension, preventing collapse

    • External Respiration: Gas exchange between air and blood

    • Internal Respiration: Gas exchange between blood and tissues

    • Cellular Respiration: Uses oxygen and food to produce ATP

    • Inhalation: Diaphragm and muscles contract

    • Exhalation: Diaphragm and muscles relax

    • Tidal Volume (Males): 0.5-1.5L

    • Tidal Volume (Females): 400 mL

    • Lung Capacity: Includes inspiratory reserve volume, expiratory reserve volume, tidal volume and residual volume

    • Oxygen Transport: Primarily by hemoglobin

    • Carbon Dioxide Transport: Primarily in the form of bicarbonate ion

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    Description

    Test your knowledge on cardiac physiology, including heart rate, cardiac output, and the electrical activity of the heart. This quiz covers the key concepts of action potentials, ECG waves, and factors affecting cardiac output. Perfect for students studying human physiology or medicine.

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