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Chapter 42

Chapter 42. Internal Transport. Diffusion Small, simple invertebrates Sponges, cnidarians, and flatworms. Invertebrates with no circulatory system. Specialized circulatory system Larger animals Blood Heart System of blood vessels Spaces through which blood circulates.

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Chapter 42

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  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

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