Cardiac Muscle Physiology Quiz
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Questions and Answers

What happens at 0mV in the heart cells?

  • K+ channels close
  • Both Ca++ and K+ channels open
  • Both Ca++ and K+ channels close (correct)
  • Ca++ channels open

    • What is the role of slow Ca++ channels during the heart's action potential?

  • Allow for the plateau phase (correct)
  • Prevent contraction
  • Initiate the action potential
  • Speed up repolarization

    • If not for endocrine control, how many times per minute would the SA node fire?

  • 80 - 100 times (correct)
  • 150 - 170 times
  • 110 - 130 times
  • 50 - 70 times

    • Which part of the heart would fire around 20 - 30 times per minute?

    <p>Atrioventricular bundle</p> Signup and view all the answers

    What is the purpose of an Electrocardiogram (ECG)?

    <p>Record electrical signals of the heart</p> Signup and view all the answers

    What is the function of the atria in the heart?

    <p>Collect blood and push it into lower chambers</p> Signup and view all the answers

    Where is the base of the heart located?

    <p>Superior and medial to the apex</p> Signup and view all the answers

    Which layer of the heart produces lubricating fluid?

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

    What is the main function of the ventricles in the heart?

    <p>Pump blood out to the body or lungs</p> Signup and view all the answers

    Which structures attach at the base of the heart?

    <p>Superior and inferior vena cava, aorta, and pulmonary trunk</p> Signup and view all the answers

    What is the role of the auricles in the heart?

    <p>Thin walled structures that can hold blood</p> Signup and view all the answers

    What is the main function of an artificial pacemaker?

    <p>Delivers electrical impulses to ensure effective heart contractions</p> Signup and view all the answers

    During which phase of the cardiac cycle does atrial contraction occur?

    <p>Atrial systole</p> Signup and view all the answers

    What is the main purpose of an Automatic External Defibrillator (AED)?

    <p>Corrects fibrillations in the heart</p> Signup and view all the answers

    Which wave corresponds to the repolarization of the ventricles?

    <p>T wave</p> Signup and view all the answers

    What happens to the semilunar valves during ventricular systole?

    <p>They open</p> Signup and view all the answers

    What is the normal amount of blood pushed out by the ventricles in one stroke called?

    <p>Stroke volume</p> Signup and view all the answers

    Which layer lines the chambers filled with blood, covers heart valves, and is continuous with the lining of blood vessels?

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

    What type of muscles do the atrioventricular valves close due to?

    <p>Papillary muscles</p> Signup and view all the answers

    What separates the heart into chambers, and are physical extensions of myocardium?

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

    What structure separates the right atrium from the right ventricle?

    <p>Tricuspid valve</p> Signup and view all the answers

    What is the primary function of purkinje fibers in the heart?

    <p>Spread the impulse around the ventricles for contraction</p> Signup and view all the answers

    Which cells in the heart have a long refractory period to prevent tetany?

    <p>Cardiac muscle cells</p> Signup and view all the answers

    What is responsible for creating a spontaneous depolarization in cardiac conductive cells?

    <p>$Na^{+}$ channels</p> Signup and view all the answers

    Which feature characterizes myocardial contractile cells during depolarization?

    <p>$Ca^{++}$ channels open and $Na^{+}$ channels close</p> Signup and view all the answers

    What is the main cause of heart murmurs?

    <p>Turbulent blood flow</p> Signup and view all the answers

    Which event marks the closing of atrioventricular valves?

    <p>S1</p> Signup and view all the answers

    What happens in the ventricle when blood is being pushed into a stiff or hypertrophic ventricle?

    <p>S4 sound is heard</p> Signup and view all the answers

    What is the normal percentage range for ejection fraction?

    <p>50% – 70%</p> Signup and view all the answers

    What is the formula for calculating Cardiac Output (CO)?

    <p>CO = HR * SV</p> Signup and view all the answers

    What does the Baroreceptor reflex primarily respond to in order to regulate heart function?

    <p>Pressure and stretch changes in the vessels</p> Signup and view all the answers

    Which substance releases acetylcholine (ACh) to slow heart rate?

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

    What condition can decrease heart rate among the following options?

    <p>Excess hydrogen ions (acidosis)</p> Signup and view all the answers

    What effect does caffeine have on heart rate?

    <p>Increases heart rate</p> Signup and view all the answers

    Study Notes

    Heart Function and Structure

    • At 0mV in heart cells, the resting potential is reached, and the cell is not permeable to sodium.
    • Slow Ca++ channels play a crucial role in the heart's action potential, specifically in the plateau phase.

    Heart Rate Regulation

    • Without endocrine control, the SA node would fire around 100 times per minute.
    • The AV node would fire around 40-60 times per minute without regulation.
    • The atrial rate would be around 20-30 times per minute without regulation.

    Electrocardiogram (ECG)

    • An ECG is used to measure the heart's electrical activity.

    Heart Structure

    • The atria are the upper chambers of the heart, responsible for receiving blood.
    • The base of the heart is located at the top of the heart, where the atria meet.
    • The epicardium produces lubricating fluid to reduce friction between the heart and surrounding tissues.
    • The ventricles are the lower chambers of the heart, responsible for pumping blood throughout the body.

    Blood Flow

    • The atrioventricular valves close due to muscle contractions.
    • The semilunar valves close during ventricular diastole.
    • The stroke volume is the normal amount of blood pushed out by the ventricles in one stroke.

    Heart Layers

    • The endocardium lines the chambers filled with blood, covers heart valves, and is continuous with the lining of blood vessels.

    Heart Conduction

    • The atrioventricular valves separate the heart into chambers and are physical extensions of myocardium.
    • The septum separates the right atrium from the right ventricle.
    • Purkinje fibers have a primary function of conducting electrical signals rapidly, allowing for coordinated contraction.

    Cardiac Cycle

    • Atrial contraction occurs during the atrial systole phase of the cardiac cycle.
    • The T-wave corresponds to the repolarization of the ventricles.

    Cardiac Assistive Devices

    • An artificial pacemaker is used to regulate heart rhythm.
    • An Automatic External Defibrillator (AED) is used to restore normal heartbeat in cardiac emergencies.

    Heart Function Abnormalities

    • Heart murmurs are primarily caused by abnormal blood flow through the heart valves.
    • The closing of atrioventricular valves marks the end of diastole and the start of systole.
    • A stiff or hypertrophic ventricle increases blood pressure, making it harder for the heart to pump blood.

    Cardiac Output and Blood Pressure

    • The normal ejection fraction range is 55-70%.
    • Cardiac Output (CO) is calculated using the formula: CO = Heart Rate x Stroke Volume.
    • The Baroreceptor reflex primarily responds to changes in blood pressure to regulate heart function.
    • The vagus nerve releases acetylcholine (ACh) to slow heart rate.

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    Chapter 19 2 PDF - Cardiovascular System

    Description

    Test your knowledge on the physiology of cardiac muscle including topics like repolarization, calcium channels, refractory period, conduction system, and endocrine control of heart rate.

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