Heart Physiology
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Questions and Answers

What is the function of the atrium in the heart?

  • To supply the main pumping force that propels the blood
  • To pump blood into the pulmonary circulation
  • To act as a primer pump for the ventricle (correct)
  • To regulate the heartbeat

    • Which ventricle pumps blood through the pulmonary circulation?

  • Neither left nor right ventricle
  • Both left and right ventricles
  • Right ventricle (correct)
  • Left ventricle

    • What is the function of the tricuspid valve?

  • To supply oxygenated blood to the body
  • To pump blood into the aorta
  • To regulate the heartbeat
  • To prevent backflow of blood from the ventricle to the atrium (correct)

    • What causes the AV valves to close?

    <p>Backward pressure gradient</p> Signup and view all the answers

    What is the difference between AV valves and semilunar valves?

    <p>AV valves are thinner and lighter, while semilunar valves are heavier</p> Signup and view all the answers

    What is the function of the chordae tendineae?

    <p>To attach the papillary muscles to the AV valves</p> Signup and view all the answers

    During which phase of the cardiac cycle do the semilunar valves close?

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

    What is the main function of gap junctions in cardiac muscle fibers?

    <p>To allow free diffusion of ions and nutrients</p> Signup and view all the answers

    What is unique about the T-tubules in cardiac muscle compared to skeletal muscle?

    <p>They are 5 times larger in diameter</p> Signup and view all the answers

    What is the function of the fibrous skeleton of the heart?

    <p>To separate the atrial and ventricular syncytium</p> Signup and view all the answers

    What is the specialized conductive system that connects the atrial and ventricular syncytium?

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

    What is the term for the network of cardiac muscle cells that can be excited simultaneously?

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

    What is the main function of the heart?

    <p>To pump blood throughout the body</p> Signup and view all the answers

    How do action potentials normally spread between the atrial and ventricular syncytium?

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

    What is the difference between the atrial and ventricular syncytium?

    <p>The atrial syncytium is separated from the ventricular syncytium by fibrous tissue</p> Signup and view all the answers

    What is the weight of the heart?

    <p>250-350 gr</p> Signup and view all the answers

    What is the result of the interconnected nature of cardiac muscle fibers?

    <p>Action potentials rapidly spread to all cells</p> Signup and view all the answers

    What is the direction of the heart in the thoracic cavity?

    <p>From right superior to left inferior</p> Signup and view all the answers

    What is the function of the intercalated disc?

    <p>To connect the heart chambers</p> Signup and view all the answers

    What is the function of the gap junction?

    <p>To connect the heart cells</p> Signup and view all the answers

    What is the result of depolarization in the heart?

    <p>Increase in intracellular Ca2+ concentration</p> Signup and view all the answers

    What is the function of the heart valves?

    <p>To prevent backflow of blood</p> Signup and view all the answers

    What is the location of the heart in the thoracic cavity?

    <p>Behind the sternum, to the left of the midline</p> Signup and view all the answers

    What is the function of the chorda tendineae in the heart?

    <p>To prevent the valves from bulging backward during ventricular contraction</p> Signup and view all the answers

    What is the main component of the myocardium?

    <p>Striated muscular cells</p> Signup and view all the answers

    What is the function of the pericardium?

    <p>To lubricate the surface of the heart during contraction and relaxation</p> Signup and view all the answers

    Which nerve has a high distribution in the atrioventricular (AV) node?

    <p>Left vagus nerve</p> Signup and view all the answers

    What is the purpose of the intercalated discs in cardiac myocytes?

    <p>To connect two adjacent muscle cells</p> Signup and view all the answers

    What is the correct order of cardiac wall thickness?

    <p>LV&gt;RV&gt;LA&gt;RA</p> Signup and view all the answers

    What is the function of the gap junctions in cardiac myocytes?

    <p>To allow rapid diffusion of ions</p> Signup and view all the answers

    Which of the following is a characteristic of cardiac myocytes?

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

    Study Notes

    Heart Physiology Overview

    • Heart physiology involves the study of the heart's electrical activity, electrocardiography, mechanical function, and overall electromechanical function.

    Heart Anatomy and Histology

    • The heart is a double muscular pump with a conic shape, located in the thoracic cavity between the lungs and slightly to the left of the midline.
    • The heart weighs around 250-350 grams and has four chambers: right atrium, left atrium, right ventricle, and left ventricle.

    Heart Chambers

    • The heart has two separate pumps: right heart for pulmonary circulation and left heart for systemic circulation.
    • Each pump has an atrium and a ventricle, with the atria serving as weak primer pumps for the ventricles.

    Heart Valves

    • The heart has four valves: tricuspid, mitral, aortic, and pulmonary valves.
    • The atrio-ventricular (AV) valves (tricuspid and mitral) prevent backflow of blood from ventricles to atria during systole.
    • The semilunar valves (aortic and pulmonary) prevent backflow from aorta and pulmonary arteries to ventricles during diastole.

    Function of Heart Valves

    • The AV valves close when a backward pressure gradient pushes blood backward and open when a forward pressure gradient forces blood in the forward direction.
    • The semilunar valves require rapid backflow for a few milliseconds to close.

    Function of Papillary Muscles and Chordae Tendineae

    • Papillary muscles attach to the vanes of the AV valves by chordae tendineae.
    • These muscles contract when ventricular walls contract, pulling the valve vanes inward to prevent bulging backward during ventricular contraction.

    Heart Layers

    • The heart has three layers: pericardium (outermost), myocardium (middle), and endocardium (innermost).
    • The pericardium is a thin fibrous sac with a small amount of fluid that lubricates the heart.
    • The myocardium is the thickest layer, composed of striated muscular cells.
    • The endocardium is the innermost layer, composed of endothelial cells.

    Nerves of the Heart

    • The heart is innervated by the autonomic nervous system, with sympathetic and parasympathetic nerves.
    • Sympathetic nerves innervate the atria, ventricles, SA node, and AV node.
    • Parasympathetic nerves (vagus nerves) have a higher distribution in the nodes (SA and AV) and a poorer distribution in the ventricles.

    Intercalated Disc and Gap Junction

    • The intercalated disc is the connection site between two adjacent muscle cells, necessary for atrial and ventricular syncytiums.
    • Gap junctions are special structures inside the intercalated discs that allow rapid diffusion of ions, oxygen, and nutrients.

    Atrial and Ventricular Syncytium

    • The heart is composed of two syncytiums: atrial and ventricular.
    • The atrial syncytium constitutes the walls of the two atria, and the ventricular syncytium constitutes the walls of the two ventricles.
    • The atria are separated from the ventricles by fibrous tissue that surrounds the atrioventricular valvular openings.

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    Test your knowledge of heart anatomy, electrical activity, and mechanical function. Covering electrocardiography, heart chambers, and valves.

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