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Anatomy of the Heart

Anatomy of the Heart. The Left Atrium Blood gathers into left and right pulmonary veins Pulmonary veins deliver to left atrium Blood from left atrium passes to left ventricle through left atrioventricular (AV) valve A two-cusped bicuspid valve or mitral valve. Anatomy of the Heart.

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Anatomy of the Heart

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  1. Anatomy of the Heart • The Left Atrium • Blood gathers into left and right pulmonary veins • Pulmonary veins deliver to left atrium • Blood from left atrium passes to left ventricle through left atrioventricular (AV) valve • A two-cusped bicuspid valve or mitral valve

  2. Anatomy of the Heart • The Left Ventricle • Holds same volume as right ventricle • Is larger; muscle is thicker and more powerful • Similar internally to right ventricle but does not have moderator band • Systemic circulation • Blood leaves left ventricle through aortic valve into ascending aorta • Ascending aorta turns (aortic arch) and becomes descending aorta

  3. Anatomy of the Heart Figure 18–6c The Sectional Anatomy of the Heart.

  4. Anatomy of the Heart • Structural Differences between the Left and Right Ventricles • Right ventricle wall is thinner, develops less pressure than left ventricle • Right ventricle is pouch-shaped, left ventricle is round

  5. Anatomy of the Heart Figure 18–7 Structural Differences between the Left and Right Ventricles

  6. Anatomy of the Heart Figure 18–7 Structural Differences between the Left and Right Ventricles

  7. Anatomy of the Heart • The Heart Valves • Two pairs of one-way valves prevent backflow during contraction • Atrioventricular (AV) valves • Between atria and ventricles • Blood pressure closes valve cusps during ventricular contraction • Papillary muscles tense chordae tendineae: prevent valves from swinging into atria

  8. Anatomy of the Heart • The Heart Valves • Semilunar valves • Pulmonary and aortic tricuspid valves • Prevent backflow from pulmonary trunk and aorta into ventricles • Have no muscular support • Three cusps support like tripod

  9. Anatomy of the Heart • Aortic Sinuses • At base of ascending aorta • Sacs that prevent valve cusps from sticking to aorta • Origin of right and left coronary arteries

  10. Anatomy of the Heart Figure 18–8a Valves of the Heart

  11. Anatomy of the Heart Figure 18–8b Valves of the Heart

  12. Anatomy of the Heart Figure 18–8c Valves of the Heart

  13. Anatomy of the Heart • Connective Tissues and the Cardiac (Fibrous) Skeleton • Physically support cardiac muscle fibers • Distribute forces of contraction • Add strength and prevent overexpansion of heart • Elastic fibers return heart to original shape after contraction

  14. Anatomy of the Heart • The Cardiac (Fibrous) Skeleton • Four bands around heart valves and bases of pulmonary trunk and aorta • Stabilize valves • Electrically insulate ventricular cells from atrial cells

  15. Anatomy of the Heart • The Blood Supply to the Heart = Coronary Circulation • Coronary arteries and cardiac veins • Supplies blood to muscle tissue of heart

  16. Anatomy of the Heart • The Coronary Arteries • Left and right • Originate at aortic sinuses • High blood pressure, elastic rebound forces blood through coronary arteries between contractions

  17. Anatomy of the Heart • Right Coronary Artery • Supplies blood to • Right atrium • Portions of both ventricles • Cells of sinoatrial (SA) and atrioventricular nodes • Marginal arteries (surface of right ventricle) • Posterior interventricular artery

  18. Anatomy of the Heart • Left Coronary Artery • Supplies blood to • Left ventricle • Left atrium • Interventricular septum

  19. Anatomy of the Heart • Two main branches of left coronary artery • Circumflex artery • Anterior interventricular artery • Arterial Anastomoses • Interconnect anterior and posterior interventricular arteries • Stabilize blood supply to cardiac muscle

  20. Anatomy of the Heart • The Cardiac Veins • Great cardiac vein • Drains blood from area of anterior interventricular artery into coronary sinus • Anterior cardiac veins • Empties into right atrium • Posterior cardiac vein, middle cardiac vein, and small cardiac vein • Empty into great cardiac vein or coronary sinus

  21. Anatomy of the Heart Figure 18–9a Coronary Circulation

  22. Anatomy of the Heart Figure 18–9b Coronary Circulation

  23. Anatomy of the Heart Figure 18–9c Coronary Circulation

  24. Anatomy of the Heart Figure 18–10 Coronary Circulation and Clinical Testing

  25. The Conducting System • Heartbeat • A single contraction of the heart • The entire heart contracts in series • First the atria • Then the ventricles

  26. The Conducting System • Two Types of Cardiac Muscle Cells • Conducting system • Controls and coordinates heartbeat • Contractile cells • Produce contractions that propel blood

  27. The Conducting System • The Cardiac Cycle • Begins with action potential at SA node • Transmitted through conducting system • Produces action potentials in cardiac muscle cells (contractile cells) • Electrocardiogram (ECG) • Electrical events in the cardiac cycle can be recorded on an electrocardiogram (ECG)

  28. The Conducting System Figure 18–11 An Overview of Cardiac Physiology

  29. The Conducting System • A system of specialized cardiac muscle cells • Initiates and distributes electrical impulses that stimulate contraction • Automaticity • Cardiac muscle tissue contracts automatically

  30. The Conducting System • Structures of the Conducting System • Sinoatrial (SA) node - wall of right atrium • Atrioventricular (AV) node - junction between atria and ventricles • Conducting cells - throughout myocardium

  31. The Conducting System • Conducting Cells • Interconnect SA and AV nodes • Distribute stimulus through myocardium • In the atrium • Internodal pathways • In the ventricles • AV bundle and the bundle branches

  32. The Conducting System • Prepotential • Also called pacemaker potential • Resting potential of conducting cells • Gradually depolarizes toward threshold • SA node depolarizes first, establishing heart rate

  33. The Conducting System Figure 18–12 The Conducting System of the Heart

  34. The Conducting System • Heart Rate • SA node generates 80–100 action potentials per minute • Parasympathetic stimulation slows heart rate • AV node generates 40–60 action potentials per minute

  35. The Conducting System • The Sinoatrial (SA) Node • In posterior wall of right atrium • Contains pacemaker cells • Connected to AV node by internodal pathways • Begins atrial activation (Step 1)

  36. The Conducting System Figure 18–13 Impulse Conduction through the Heart

  37. The Conducting System • The Atrioventricular (AV) Node • In floor of right atrium • Receives impulse from SA node (Step 2) • Delays impulse (Step 3) • Atrial contraction begins

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