CHAPTER 49 Circulatory Systems

1. CHAPTER 49Circulatory Systems

2. Chapter 49: Circulatory Systems Circulatory Systems: Pumps, Vessels, and Blood Vertebrate Circulatory Systems The Human Heart: Two Pumps in One

3. Chapter 49: Circulatory Systems The Vascular System: Arteries, Capillaries, and Veins Blood: A Fluid Tissue Control and Regulation of Circulation

4. Circulatory Systems: Pumps, Vessels, and Blood • Metabolic needs of the cells of small aquatic animals are met by direct exchange of materials with the external medium. • Those of the cells of larger animals are met by a circulatory system that transports nutrients, respiratory gases, and metabolic wastes throughout the body. Review Figure 49.1 4

5. figure 49-01.jpg 49.1 Figure 49.1

6. Circulatory Systems: Pumps, Vessels, and Blood • In open circulatory systems the blood or tissue fluid leaves vessels and percolates through tissues. Review Figure 49.2 6

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8. Circulatory Systems: Pumps, Vessels, and Blood • In closed circulatory systems the blood is contained in a system of vessels. Review Figure 49.3 8

9. figure 49-03.jpg 49.3 Figure 49.3

10. Vertebrate Circulatory Systems • The circulatory systems of vertebrates consist of a heart and a closed system of vessels containing blood separate from tissue fluid. • Arteries and arterioles carry blood from the heart; • Capillaries are the site of exchange between blood and tissue fluid; • Venules and veins carry blood back to the heart. 10

11. Vertebrate Circulatory Systems • The vertebrate heart evolved from two chambers in fishes to three in amphibians and reptiles and four in crocodilians, mammals, and birds. • This progression has led to an increasing separation of blood flow to the gas exchange organs and to the rest of the body. 11

12. Vertebrate Circulatory Systems • In birds and mammals, blood circulates through the pulmonary circuit and the systemic circuit. 12

13. The Human Heart: Two Pumps in One • The human heart has four chambers. • Valves prevent the backflow of blood. Review Figure 49.4 13

14. figure 49-04a.jpg 49.4 Figure 49.4 – Part 1

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16. The Human Heart: Two Pumps in One • The cardiac cycle has two phases: systole, in which the ventricles contract; and diastole, in which they relax. • Sequential heart sounds are made by heart valves closing. Review Figure 49.5 16

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18. The Human Heart: Two Pumps in One • Blood pressure can be measured using a sphygmomanometer and a stethoscope. Review Figure 49.6 18

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20. The Human Heart: Two Pumps in One • The autonomic nervous system controls heart rate. • Sympathetic activity increases it, parasympathetic activity decreases it. • This is due to the effects of norepinephrine and acetylcholine on the depolarization rate of the membranes of pacemaker cells. Review Figure 49.7 20

21. figure 49-07.jpg 49.7 Figure 49.7

22. The Human Heart: Two Pumps in One • The sinoatrial node controls the cardiac cycle by initiating a wave of depolarization in the atria, which is conducted to the ventricles through the atrioventricular node. Review Figure 49.8 22

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24. The Human Heart: Two Pumps in One • The EKG records electric potentials resulting from contraction and relaxation of cardiac muscles. Review Figure 49.9 24

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26. The Vascular System: Arteries, Capillaries, and Veins • Arteries and arterioles have many elastic fibers enabling them to withstand high pressures. • Abundant smooth muscle cells allow them to contract and expand, altering their resistance and thus blood flow. Review Figure 49.10 26

27. figure 49-10a.jpg 49.10 Figure 49.10 – Part 1

28. figure 49-10b.jpg 49.10 Figure 49.10 – Part 2

29. The Vascular System: Arteries, Capillaries, and Veins • Capillary beds are the site of exchange of materials between blood and tissue fluid. 29

30. The Vascular System: Arteries, Capillaries, and Veins • Fluid exchange between blood and tissues is determined by the balance between blood pressure and osmotic potential in the capillaries. Review Figure 49.12 30

31. figure 49-12.jpg 49.12 Figure 49.12

32. The Vascular System: Arteries, Capillaries, and Veins • The ability of a specific molecule to cross a capillary wall depends on • Capillary architecture, • type of substance, and • concentration gradient between the blood and tissue fluid. 32

33. The Vascular System: Arteries, Capillaries, and Veins • A separate system of vessels, the lymphatic system, returns the tissue fluid to the blood. 33

34. The Vascular System: Arteries, Capillaries, and Veins • Veins have a high capacity for storing blood. Aided by gravity, contractions of skeletal muscle, and the actions of breathing, they carry blood back to the heart. Review Figure 49.13 34

35. figure 49-13.jpg 49.13 Figure 49.13

36. The Vascular System: Arteries, Capillaries, and Veins • Cardiovascular disease is responsible for about half of all deaths in the U.S. and Europe. • Atherosclerosis and thrombus formation can lead to potentially fatal conditions such as heart attack and stroke. • Diet and behavior are the keys to good cardiovascular health. 36

37. Blood: A Fluid Tissue • Blood can be divided into a plasma portion and a cellular portion. • All of the cellular components are produced from stem cells in the bone marrow. Review Figure 49.15 37

38. figure 49-15.jpg 49.15 Figure 49.15

39. Blood: A Fluid Tissue • Red blood cells transport respiratory gases. • Their production in the bone marrow is stimulated by erythropoietin, which is produced in response to hypoxia in the tissues. Review Figure 49.16 39

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41. Blood: A Fluid Tissue • Platelets, along with circulating proteins, are involved in clotting responses. Review Figure 49.17 41

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43. Figure 49.17 – Part 2 Figure 49.17 – Part 2 figure 49-17b.jpg 49.17

44. Blood: A Fluid Tissue • Plasma is a complex solution containing gases, ions, nutrient molecules, proteins, and other molecules. 44

45. Control and Regulation of Circulation • Blood flow through capillary beds is controlled by local autoregulation mechanisms, hormones, and the autonomic nervous system. Review Figure 49.18 45

46. figure 49-18.jpg 49.18 Figure 49.18

47. Control and Regulation of Circulation • Blood pressure is controlled in part by the hormones vasopressin and angiotensin, which stimulate contraction of blood vessels. Review Figure 49.19 47

48. figure 49-19.jpg 49.19 Figure 49.19

49. Control and Regulation of Circulation • Heart rate is controlled by the autonomic nervous system. • It responds to information about blood pressure and blood composition that is integrated by the brain’s regulatory centers. Review Figure 49.20 49

50. figure 49-20.jpg 49.20 Figure 49.20