Chapter 42

1. Chapter 42 Internal Transport

2. Diffusion • Small, simple invertebrates • Sponges, cnidarians, and flatworms

3. Invertebrates with no circulatory system

4. Specialized circulatory system • Larger animals • Blood • Heart • System of blood vessels • Spaces through which blood circulates

5. Interstitial fluid • Tissue fluid between cells • Brings oxygen and nutrients into contact with cells • All animals

6. Open circulatory system • Arthropods and most mollusks • Blood flows into a hemocoel • Bathes the tissues directly

7. Closed circulatory system • Some invertebrates • All vertebrates • Blood flows through a continuous circuit of blood vessels

8. Closed circulatory system

9. Vertebrate circulatory system • Muscular heart • Arteries • Capillaries • Veins

10. Vertebrate circulatory system • Transports nutrients, oxygen, wastes, and hormones • Helps maintain • Fluid balance • Appropriate pH • Body temperature • Defends body against disease

11. Plasma • Water • Salts • Substances in transport • Plasma proteins • Albumins • Globulins • Fibrinogen

12. Blood components

13. Red blood cells (erythrocytes) • Transport oxygen and carbon dioxide • Produce large quantities of hemoglobin • Red pigment that binds with oxygen

14. White blood cells (leukocytes) • Defend the body against disease organisms • Agranular white blood cells • Lymphocytes • Monocytes

15. Granular white blood cells • Neutrophils • Eosinophils • Basophils

16. Platelets • Patch damaged blood vessels • Release substances essential for blood clotting

17. Blood clotting • Damaged cells and platelets release substances that activate clotting factors • Prothrombin is converted to thrombin

18. Thrombin catalyzes the conversion of fibrinogen to an insoluble protein, called fibrin • Fibrin forms long threads that form the webbing of the clot

19. Blood clotting

20. Arteries • Carry blood away from the heart • Veins • Return blood to the heart

21. Arterioles • Constrict (vasoconstriction) • Dilate (vasodilation) • Regulate blood pressure and distribution of blood to the tissues

22. Capillaries • Thin-walled exchange vessels through which blood and tissues exchange materials

23. Blood flow through a capillary network

24. Vertebrate heart • One or two atria • Receive blood • One or two ventricles • Pump blood into the arteries

25. Fish heart • Single atrium and ventricle • Part of a single circuit of blood flow

26. Terrestrial vertebrates • Complex circulatory systems separate oxygen-rich from oxygen-poor blood • Allows the higher metabolic rate needed to support an active terrestrial lifestyle

27. Amphibians • Two atria and a ventricle • Blood flows through a double circuit • Oxygen-rich blood is partly separated from oxygen-poor blood

28. Most reptiles • Wall that partly divides the ventricles, minimizing the mixing of oxygen-rich and oxygen-poor blood

29. Birds and mammals • Four-chambered hearts separate oxygen-rich blood from oxygen-poor blood

30. Human heart • Enclosed by a pericardium • Valves that prevent backflow of blood

31. Right atrioventricular (AV) valve (tricuspid valve) • Between right atrium & ventricle • Mitral valve • Between left atrium and ventricle • Semilunar valves • Guard the exits from the heart

32. Human heart

33. Cardiac muscle fibers are joined by intercalated discs • The sinoatrial (SA) node (pacemaker) initiates each heartbeat • A specialized electrical conduction system coordinates heartbeats

34. Cardiac cycle • One complete heartbeat • Contraction occurs during systole • Period of relaxation is diastole

35. Beginning of ventricular systole • Closing of the AV valves • Low-pitched “lub” sound • Beginning of ventricular diastole • Closing of the semilunar valves • Short, loud, sharp “dup” sound

36. Cardiac output (CO) • Stroke volume times heart rate • Stroke volume depends on venous return and on neural messages and hormones, especially epinephrine and norepinephrine

37. Starling’s law of the heart • The more blood delivered to the heart by the veins, the more blood the heart pumps

38. Heart rate • Regulated mainly by the nervous system • Influenced by hormones and body temperature

39. Blood pressure • Force blood exerts against the inner walls of the blood vessel • Greatest in the arteries • Decreases as blood flows through the capillaries

40. Blood pressure depends on • Cardiac output • Blood volume • Resistance to blood flow

41. Peripheral resistance • Resistance to blood flow • Blood viscosity • Friction between blood and blood vessel wall

42. Blood pressure

43. Baroreceptors • Sensitive to blood pressure changes • Send messages to the cardiac and vasomotor centers in the medulla of the brain

44. When blood pressure increases • Cardiac center stimulates parasympathetic nerves that slow heart rate • Vasomotor center inhibits sympathetic nerves that constrict blood vessels • Blood pressure is reduced

45. Angiotensin • Hormone that raises blood pressure • Aldosterone • Helps regulate salt excretion • Affects blood volume and blood pressure

46. Pulmonary circulation • Connects heart and lungs • Systemic circulation • Connects heart and tissues

47. Pulmonary circulation • Right ventricle pumps blood into the pulmonary arteries, one going to each lung • Blood circulates through pulmonary capillaries in the lung • Blood is conducted to the left atrium by a pulmonary vein

48. Systemic circulation • Left ventricle pumps blood into the aorta • Aorta branches into arteries leading to the body organs • Blood flows through capillary networks within various organs

49. Blood flows into veins that conduct it to the superior vena cava or inferior vena cava • Blood returns to the right atrium

50. Systemic and pulmonary circulation