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Chapter 19 The Heart

Chapter 19 The Heart. Circulatory system heart, blood vessels and blood Cardiovascular system heart, arteries, veins and capillaries; 2 major divisions Pulmonary circuit - right side of heart carries blood to lungs for gas exchange Systemic circuit - left side of heart

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Chapter 19 The Heart

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  1. Chapter 19 The Heart • Circulatory system • heart, blood vessels and blood • Cardiovascular system • heart, arteries, veins and capillaries; 2 major divisions • Pulmonary circuit - right side of heart • carries blood to lungs for gas exchange • Systemic circuit - left side of heart • supplies blood to all organs of the body

  2. Cardiovascular System Circuit

  3. Size, Shape and Position • Located in mediastinum, between lungs • Base - broad superior portion of heart • Apex - inferior end, tilts to the left, tapers to point • 3.5 in. wide at base, 5 in. from base to apex and 2.5 in. anterior to posterior; weighs 10 oz

  4. Heart Position

  5. Pericardium • Allows heart to beat without friction, room to expand and resists excessive expansion • Parietal pericardium • outer, tough, fibrous layer of CT • inner, thin, smooth, moist serous layer • Pericardial cavity • filled with pericardial fluid • Visceral pericardium (a.k.a. epicardium of heart wall) • thin, smooth, moist serous layer covers heart surface

  6. Heart Wall • Epicardium (a.k.a. visceral pericardium) • serous membrane covers heart • Myocardium • thick muscular layer • fibrous skeleton - network of collagenous and elastic fibers • provides structural support • attachment for cardiac muscle • nonconductor important in coordinating contractile activity • Endocardium • smooth inner lining

  7. Pericardium & Heart Wall • Pericardial cavity contains 5-30 ml of pericardial fluid

  8. Heart Chambers • 4 chambers • Right and left atria • 2 superior, posterior chambers • receive blood returning to heart • Right and left ventricles • 2 inferior chambers • pump blood into arteries • Atrioventricular sulcus - separates atria, ventricles • Anterior and posterior sulci - grooves separate ventricles (next slide)

  9. External Anatomy - Anterior Atrioventricular sulcus

  10. External Anatomy - Posterior

  11. Anterior Aspect

  12. Heart Chambers - Internal • Interatrial septum • wall that separates atria • Pectinate muscles • internal ridges of myocardium in right atrium and both auricles • Interventricular septum • wall that separates ventricles • Trabeculae carneae • internal ridges in both ventricles

  13. Internal Anatomy Anterior Aspect

  14. Internal Anatomy, Anterior Aspect

  15. Heart Internal Anatomy • Heart bisected in frontal plane, opened like a book

  16. Heart Valves • Ensure one-way blood flow • Atrioventricular (AV) valves • right AV valve has 3 cusps (tricuspid valve) • left AV valve has 2 cusps (mitral,bicuspid valve) lamb • chordae tendineae - cords connect AV valves to papillary muscles (on floor of ventricles) • Semilunar valves - control flow into great arteries • pulmonary: from right ventricle into pulmonary trunk • aortic: from left ventricle into aorta

  17. Heart Valves

  18. Heart Valves

  19. AV Valve Mechanics • Ventricles relax, pressure drops, semilunar valves close, AV valves open, blood flows from atria to ventricles • Ventricles contract, AV valves close(papillary m. contract and pull on chordae tendineae to prevent prolapse),pressure rises, semilunar valves open, blood flows into great vessels

  20. Operation of Atrioventricular Valves

  21. Operation of Semilunar Valves

  22. Blood Flow Through Heart

  23. Coronary Circulation • Blood vessels nourish cardiac muscle • Left coronary artery • anterior interventricular artery • supplies interventricular septum + anterior walls of ventricles • circumflex artery • passes around left side of heart in coronary sulcus, supplies left atrium and posterior wall of left ventricle • Right coronary artery • marginal artery • supplies lateral R atrium + ventricle • posterior interventricular artery • supplies posterior walls of ventricles

  24. Venous Drainage • 20% drains directly into right ventricle • 80% returns to right atrium • great cardiac vein (anterior interventricular sulcus) • middle cardiac vein (posterior sulcus) • coronary sinus (posterior coronary sulcus) collects blood from these and smaller veins and empties into right atrium

  25. Coronary Vessels - Anterior

  26. Coronary Vessels - Posterior

  27. Coronary Flow and the Cardiac Cycle • Reduced during ventricular contraction • arteries compressed • Increased during ventricular relaxation • openings to coronary arteries, just above aortic semilunar valve, fill as blood surges back to valve

  28. Structure of Cardiac Muscle Cell

  29. Metabolism of Cardiac Muscle • Aerobic respiration • Rich in myoglobin and glycogen • Large mitochondria • Organic fuels: fatty acids, glucose, ketones • Fatigue resistant

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