CARDIO-HEART
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Questions and Answers

During which phase of an action potential in cardiac muscle do Ca2+ channels remain open?

  • Plateau phase (correct)
  • Pacemaker potential
  • Repolarization phase
  • Depolarization phase

    • What is the primary role of the sinoatrial node in the heart?

  • It prevents backflow of blood.
  • It coordinates atrial contraction.
  • It serves as the heart's main pacemaker. (correct)
  • It stimulates increased cardiac output.

    • Which wave in an electrocardiogram (ECG) represents the depolarization of the ventricles?

  • T wave
  • QRS complex (correct)
  • R wave
  • P wave

    • What is the function of the AV node in the heart's electrical conduction system?

    <p>To delay the signal before it moves to the ventricles</p> Signup and view all the answers

    Which of the following best describes the cardiac cycle?

    <p>The contraction and relaxation phases of the heart</p> Signup and view all the answers

    What causes the prolonged action potential duration in cardiac muscle compared to skeletal muscle?

    <p>Sustained Ca2+ channel opening</p> Signup and view all the answers

    What does the T wave in an ECG indicate?

    <p>Ventricular repolarization</p> Signup and view all the answers

    Which component of the cardiac conduction system follows the AV node?

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

    What is the primary function of the systemic circuit?

    <p>Carries oxygen-rich blood from the heart to the body</p> Signup and view all the answers

    What opens into the aorta?

    <p>Left ventricle</p> Signup and view all the answers

    Which structure of the heart is primarily responsible for pumping blood to the body?

    <p>Left ventricle</p> Signup and view all the answers

    Which valves are involved in the blood flow from the left atrium to the left ventricle?

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

    Which artery supplies blood to the right ventricle?

    <p>Right coronary artery</p> Signup and view all the answers

    Where do the coronary arteries originate?

    <p>From the base of the aorta above the aortic semilunar valve</p> Signup and view all the answers

    After entering the left atrium, blood is received from which vessels?

    <p>Pulmonary veins</p> Signup and view all the answers

    What is the nature of blood carried by the aorta?

    <p>Oxygen-rich, carbon dioxide-poor</p> Signup and view all the answers

    Which structure separates the right and left atria?

    <p>Interatrial septum</p> Signup and view all the answers

    What distinguishes the ventricles from the atria in terms of structure and function?

    <p>Ventricles are the pumping chambers with thick, strong walls.</p> Signup and view all the answers

    What is the primary function of the atrioventricular valves?

    <p>To ensure one-way blood flow between atria and ventricles.</p> Signup and view all the answers

    Which feature is characteristic of cardiac muscle tissue?

    <p>Cardiac muscle is striated and contains intercalated disks.</p> Signup and view all the answers

    Which phase of the cardiac cycle is characterized by the contraction of the ventricles?

    <p>Isovolumetric contraction</p> Signup and view all the answers

    What is the main purpose of the coronary sulcus in the heart?

    <p>To separate the atria from the ventricles.</p> Signup and view all the answers

    Which of the following statements about cardiac electrical conduction is true?

    <p>Purkinje fibers are responsible for carrying signals through the ventricles.</p> Signup and view all the answers

    What role do valves play in the heart's functioning?

    <p>They ensure unidirectional blood flow through the circulatory system.</p> Signup and view all the answers

    Study Notes

    Cardiac Action Potentials

    • Depolarization: Sodium (Na+) and Calcium (Ca2+) channels open, allowing ions to enter the cell.
    • Plateau: Sodium (Na+) channels close, some Potassium (K+) channels open, and Calcium (Ca2+) channels remain open, prolonging the action potential.
    • Repolarization: Potassium (K+) channels are open, Calcium (Ca2+) channels close, allowing potassium to exit the cell.
    • Duration: Action potentials in cardiac muscle last significantly longer (200-500 msec) compared to skeletal muscle (2 msec) due to the plateau phase.

    Cardiac Conduction System

    • Function: Conducts electrical impulses throughout the heart, coordinating the contraction of atria and ventricles.
    • Sinoatrial Node (SA Node): Located in the right atrium, initiates action potentials, acts as the heart's pacemaker, and contains a large number of Calcium (Ca2+) channels.

    Path of Action Potential Through the Heart

    • SA node
    • AV node (Atrioventricular)
    • AV bundle
    • Right and Left Bundle Branches
    • Purkinje Fibers

    Electrocardiogram (ECG/EKG)

    • Purpose: Records electrical activity of the heart, diagnoses cardiac abnormalities, and uses electrodes to measure electrical changes.
    • Components:
      • P Wave: Depolarization of the atria.
      • QRS Complex: Depolarization of the ventricles.
      • T Wave: Repolarization of the ventricles.

    Left Side of the Heart

    • Systemic Circuit: Carries oxygen-rich blood from the heart to the body.

    Left Atrium

    • Receives oxygen-rich blood from the lungs through four pulmonary veins.

    Left Ventricle

    • Pumps oxygen-rich blood to the aorta to the body.
    • Has a thicker wall and contracts more forcefully than the right ventricle to overcome higher pressure in the systemic circuit.

    Aorta

    • Carries oxygen-rich blood from the left ventricle to the rest of the body.

    Blood Flow Through the Heart

    • Right Atrium (RA)
    • Tricuspid Valve
    • Right Ventricle (RV)
    • Pulmonary Semilunar Valve
    • Pulmonary Trunk
    • Pulmonary Arteries
    • Lungs
    • Pulmonary Veins
    • Left Atrium (LA)
    • Bicuspid Valve
    • Left Ventricle (LV)
    • Aortic Semilunar Valve
    • Aorta
    • Body

    Blood Supply to the Heart

    • Coronary Arteries: Branch directly from the aorta, supplying blood to the heart wall.
      • Left Coronary Artery: Branches to supply the anterior heart wall and the left ventricle.
      • Right Coronary Artery: Supplies the right ventricle.

    Cardiac Muscle

    • Characteristics: Centrally located nucleus, branching cells, rich in mitochondria, striated with actin and myosin, uses Calcium (Ca2+) and ATP for contractions, and interconnected cells via intercalated disks.

    Chambers and Blood Vessels

    • Chambers: Left Atrium (LA), Right Atrium (RA), Left Ventricle (LV), and Right Ventricle (RV).
    • Coronary Sulcus: Separates the atria from the ventricles.

    Atria

    • Upper portion of the heart, holding chambers.
    • Small, thin-walled, and contract minimally to push blood into the ventricles.
    • Interatrial Septum: Separates the right and left atria.

    Ventricles

    • Lower portion of the heart, pumping chambers
    • Thick, strong-walled, and contract forcefully to propel blood out of the heart
    • Interventricular Septum: Separates the right and left ventricles.

    Heart Valves

    • Function: Ensure one-way blood flow through the heart.
    • Atrioventricular Valves (AV): Located between the atria and ventricles.
      • Tricuspid Valve: Located between the right atrium (RA) and right ventricle (RV), has three cusps.

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