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Cardiovascular System

Cardiovascular System. Chapter 15. 15-1. Chapter 15 Cardiovascular System. heart blood vessels. Average Size of Heart 14 cm long 9 cm wide. 15-2. Location of Heart. posterior to sternum medial to lungs anterior to vertebral column base lies beneath 2 nd rib

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Cardiovascular System

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  1. Cardiovascular System Chapter 15 15-1

  2. Chapter 15Cardiovascular System • heart • blood vessels • Average Size of Heart • 14 cm long • 9 cm wide 15-2

  3. Location of Heart • posterior to sternum • medial to lungs • anterior to vertebral column • base lies beneath 2nd rib • apex at 5th intercostal space • lies upon diaphragm 15-3

  4. Coverings of Heart 15-4

  5. Wall of Heart • Three layers • endocardium • forms protective inner lining • membrane of epithelial and connective tissues • myocardium • cardiac muscle • contracts to pump blood • epicardium • serous membrane • protective covering • contains capillaries and nerve fibers 15-5

  6. Heart Chambers • Right Atrium • receives blood from • inferior vena cava • superior vena cava • coronary sinus • sends blood to right ventricle • Left Atrium • receives blood from pulmonary veins • sends blood to left ventricle • Right Ventricle • receives blood from right atrium • sends blood to lungs • Left Ventricle • receives blood from left atrium • sends blood to body 15-6

  7. Heart Valves • Tricuspid Valve • right A-V valve • between right atrium and right ventricle • Bicuspid Valve (Mitral) • left A-V valve • between left atrium and left ventricle • Aortic Valve • semilunar valve • between left ventricle and aorta • Pulmonary Valve • semilunar valve • between right ventricle and pulmonary trunk 15-7

  8. Coronal Sections of Heart 15-8

  9. Heart Valves Tricuspid Valve Pulmonary and Aortic Valve 15-9

  10. Skeleton of Heart • fibrous rings to which the heart valves are attached 15-10

  11. Path of Blood Through the Heart 15-11

  12. Path of BloodThrough the Heart 15-12

  13. Blood Supply to Heart 15-13

  14. Blood Supply to Heart 15-14

  15. Angiogram of Coronary Arteries 15-15

  16. Heart Actions Atrial Diastole/Ventricular Systole Atrial Systole/Ventricular Diastole 15-16

  17. Cardiac Cycle • Atrial Systole/Ventricular Diastole • blood flows passively into ventricles • remaining 30% of blood pushed into ventricles • A-V valves open/semilunar valves close • ventricles relaxed • ventricular pressure increases • Ventricular Systole/Atrial diastole • A-V valves close • chordae tendinae prevent cusps of valves from bulging too far into atria • atria relaxed • blood flows into atria • ventricular pressure increases and opens semilunar valves • blood flows into pulmonary trunk and aorta 15-17

  18. Heart Sounds • Lubb • first heart sound • occurs during ventricular contraction • A-V valves closing • Dupp • second heart sound • occurs at completion of ventricular contraction • semilunar valves closing Murmur – abnormal heart sound 15-18

  19. Heart Sounds 15-19

  20. Cardiac Muscle Fibers • Cardiac muscle fibers form functional syncytia • group of cells that function as a unit • atrial syncytium • ventricular syncytium 15-20

  21. Cardiac Conduction System 15-21

  22. Cardiac Conduction System 15-22

  23. Muscle Fibers in Ventricular Walls 15-23

  24. Electrocardiogram • recording of electrical changes that occur in the myocardium • used to assess heart’s ability to conduct impulses P wave – atrial depolarizatoin QRS wave – ventricular depolarization T wave – ventricular repolarization 15-24

  25. Electrocardiogram 15-25

  26. Electrocardiogram A prolonged QRS complex may result from damage to the A-V bundle fibers 15-26

  27. Summary of Changes During Cardiac Cycle 15-27

  28. Regulation of Cardiac Cycle • physical exercise • body temperature • concentration of various ions • potassium • calcium • parasympathetic impulses decrease heart action • sympathetic impulses increase heart action • cardiac center regulates autonomic impulses to the heart 15-28

  29. Regulation of Cardiac Cycle Autonomic nerve impulses alter the activities of the S-A and A-V nodes 15-29

  30. Blood Vessels • arteries • carry blood away from ventricles of heart • arterioles • receive blood from arteries • carry blood to capillaries • capillaries • sites of exchange of substances between blood and body cells • venules • receive blood from capillaries • veins • carry blood toward ventricle of heart 15-30

  31. Arteries and Arterioles • Arterioles • thinner wall than artery • endothelial lining • some smooth muscle tissue • small amount of connective tissue • helps control blood flow into a capillary • Artery • thick strong wall • endothelial lining • middle layer of smooth muscle and elastic tissue • outer layer of connective tissue • carries blood under relatively high pressure 15-31

  32. Walls of Artery and Vein 15-32

  33. Arteriole • smallest arterioles only have a few smooth muscle fibers • capillaries lack muscle fibers 15-33

  34. Metarteriole connects arteriole directly to venule 15-34

  35. Capillaries • smallest diameter blood vessels • extensions of inner lining of arterioles • walls are endothelium only • semipermeable • sinusoids – leaky capillaries 15-35

  36. Capillary Network 15-36

  37. Regulation of Capillary Blood Flow • Precapillary sphincters • may close a capillary • respond to needs of the cells • low oxygen and nutrients cause sphincter to relax 15-37

  38. Exchange in the Capillaries • water and other substances leave capillaries because of net outward pressure at the capillaries’s arteriolar ends • water enters capillaries’s venular ends because of a net inward pressure • substances move in and out along the length of the capillaries according to their respective concentration gradients 15-38

  39. Venules and Veins • Venule • thinner wall than arteriole • less smooth muscle and elastic tissue than arteriole • Vein • thinner wall than artery • three layers to wall but middle layer is poorly developed • some have flaplike valves • carries blood under relatively low pressure • serves as blood reservoir 15-39

  40. Venous Valves 15-40

  41. Blood Volumes in Vessels 15-41

  42. Arterial Blood Pressure Blood Pressure – force the blood exerts against the inner walls of the blood vessels • Arterial Blood Pressure • rises when ventricles contract • falls when ventricles relax • systolic pressure – maximum pressure • diastolic pressure – minimum pressure 15-42

  43. Pulse • alternate expanding and recoiling of the arterial wall that can be felt 15-43

  44. Factors That InfluenceArterial Blood Pressure 15-44

  45. Control of Blood Pressure Controlling cardiac output and peripheral resistance regulates blood pressure 15-45

  46. Control of Blood Pressure If blood pressure rises, baroreceptors initiate the cardioinhibitory reflex, which lowers the blood pressure 15-46

  47. Control of Blood Pressure Dilating arterioles helps regulate blood pressure 15-47

  48. Venous Blood Flow • not a direct result of heart action • depends on skeletal muscle contraction • depends on breathing • depends on venoconstriction 15-48

  49. Central Venous Pressure • pressure in the right atrium • factors that influence it alter flow of blood into the right atrium • affects pressure within the peripheral veins • weakly beating heart increases central venous pressure • increase in central venous pressure causes blood to back up into peripheral vein 15-49

  50. Pulmonary Circuit • consists of vessels that carry blood from the heart to the lungs and back to the heart 15-50

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