D Cardiovascular system Anatomy and Physiology

1. D Cardiovascular system Anatomy and Physiology

2. Chapter 15 1

3. Chapter 15Cardiovascular System 2

4. Size of Heart • Average Size of Heart • 14 cm long • 9 cm wide 3

5. 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 4

6. Coverings of Heart 5

7. Wall of the Heart 6

8. Wall of the Heart 7

9. Heart Chambers • Right Atrium • receives blood from • inferior vena cava • superior vena cava • coronary sinus • Left Atrium • receives blood from pulmonary veins • Right Ventricle • receives blood from right atrium • Left Ventricle • receives blood from left atrium 8

10. Heart Valves 9

11. Coronal Sections of Heart 10

12. Heart Valves Tricuspid Valve Pulmonary and Aortic Valve 11

13. Skeleton of Heart • fibrous rings to which the heart valves are attached 12

14. Path of Blood Through the Heart 13

15. Path of BloodThrough the Heart 14

16. Blood Supply to Heart 15

17. Blood Supply to Heart 16

18. Angiogram of Coronary Arteries 17

19. Heart Actions Atrial Diastole/Ventricular Systole Atrial Systole/Ventricular Diastole 18

20. 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 19

21. Cardiac Cycle • 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 20

22. Heart Sounds • Lubb • first heart sound • occurs during ventricular systole • A-V valves closing • Dupp • second heart sound • occurs during ventricular diastole • pulmonary and aortic semilunar valves closing Murmur – abnormal heart sound 21

23. Heart Sounds 22

24. Cardiac Muscle Fibers • Cardiac muscle fibers form a functional syncytium • group of cells that function as a unit • atrial syncytium • ventricular syncytium 23

25. Cardiac Conduction System 24

26. Cardiac Conduction System 25

27. Muscle Fibers in Ventricular Walls 26

28. Electrocardiogram • recording of electrical changes that occur in the myocardium • used to assess heart’s ability to conduct impulses P wave – atrial depolarization QRS wave – ventricular depolarization T wave – ventricular repolarization 27

29. Electrocardiogram 28

30. Electrocardiogram A prolonged QRS complex may result from damage to the A-V bundle fibers 29

31. Clinical Application Arrhythmias • Ventricular fibrillation • rapid, uncoordinated depolarization of ventricles • Tachycardia • rapid heartbeat • Atrial flutter • rapid rate of atrial depolarization 30

32. Cardiac Cycle 31

33. Regulation of Cardiac Cycle Autonomic nerve impulses alter the activities of the S-A and A-V nodes 32

34. Regulation of Cardiac Cycle Additional Factors that Influence HR • 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 33

35. 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 34

36. 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 35

37. Walls of Artery and Vein 36

38. Arteriole • smallest arterioles only have a few smooth muscle fibers • capillaries lack muscle fibers 37

39. Metarteriole connects arteriole directly to venule 38

40. Capillaries • smallest diameter blood vessels • extensions of inner lining of arterioles • walls are endothelium only • semipermeable • sinusoids – leaky capillaries 39

41. Capillary Network 40

42. 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 41

43. Exchange in the Capillaries • water and other substances leave capillaries because of net outward pressure at the capillaries’ arteriolar ends • water enters capillaries’ 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 42

44. 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 43

45. Venous Valves 44

46. Characteristics of Blood Vessels 45

47. Blood Volumes in Vessels 46

48. 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 47

49. Pulse • alternate expanding and recoiling of the arterial wall that can be felt 48

50. Factors That InfluenceArterial Blood Pressure 49