Circulatory System

1. Circulatory System Chapter 42 A. P. Biology Liberty Senior High Mr. Knowles

2. What’s the purpose of the cardiovascular system?Do all organisms have one?

3. Unicellular Organisms Use simple diffusion for moving nutrients and oxygen into cell; wastes and carbon dioxide out of cell. Problem: Surface area – to – volume ratio; limits the size.

4. Phylum Nemotoda Use a body cavity – to transport materials to more distant cells. Not a true circulatory system. Problem: limited by size of organism or distance cells can be from body cavity.

5. Open and Closed Circulatory Systems More complex animals Have one of two types of circulatory systems: open or closed Both of these types of systems have three basic components A circulatory fluid (blood) A set of tubes (blood vessels) A muscular pump (the heart)

6. In insects, other arthropods, and most molluscs: Blood bathes the organs directly in an open circulatory system

9. Two Types of Circulatory Systems Open Circulatory System- no distinct circulating fluid, body fluid is the circulating fluid. Muscular pump pushes fluid through channels and spaces in body. Fluid drains back into central cavity. Arthropods (Insects, Crustaceans)

10. In a closed circulatory system: Blood is confined to vessels and is distinct from the interstitial fluid

11. Two Types of Circulatory Systems Closed Circulatory System- circulating fluid is enclosed within blood vessels; does not mix with other body fluids. Materials diffuse through vessel walls to tissues. Examples: Annelids and all vertebrates.

17. Two Major Circuits Pulmonary Circuit: carries blood to & from the gas exchange surfaces of the lungs. Systemic Circuit: which transports blood to & from the rest of the body.

18. Why we need a cardiovascular system! Human embryos before 3 weeks are so small, materials are transported by simple diffusion. At third week (few mms in length), heart begins beating- first organ system to function. Supplies nutrients to all 75 trillion cells in the body.

19. Evolution of Vertebrate Heart Recall what the human heart looks like.

21. Why a heart? More active lifestyle: change from filter- feeding to active prey capture; requires more efficient respiration and circulation. Invasion of land: change in respiration system and endothermy.

22. Early Chordates Heart = simple tube heart; thicker muscular artery that contracted. Was a peristaltic pump. Problem: blood is pushed in both directions; inefficient. Ex. Lancelets.

23. Fish Heart True chambered-pump heart. A tube with four consecutive chambers. Sinus venosus- collects blood from body. Atrium- receives blood from the S.V. Ventricle- pumping chamber. Conus arteriosus- smaller, elongated pump. “Two-chambered” heart in peristaltic sequence; 1 atrium, 1 ventricle. Fig. 46.36

25. Fishes A fish heart has two main chambers One ventricle and one atrium. Blood pumped from the ventricle Travels to the gills, where it picks up O2 and disposes of CO2

26. Fish Heart Blood goes from Heart ? Gills ? Becomes Oxygenated ? Arteries to Body Tissues ? Veins Return to Heart Benefit: peripheral tissues receive fully oxygenated blood directly from gills. Problem: blood loses pressure from gills to body; no pulmonary circulation.

28. Amphibian Heart Fully terrestrial lungs require a pulmonary circuit. Uses pulmonary arteries/veins to oxygenate blood and return to heart for repumping. Higher pressure out to peripheral tissues. “Three-chambered” heart; 2 Atria, 1 ventricle.

31. Amphibians Frogs and other amphibians: Have a three-chambered heart, with two atria and one ventricle. The ventricle pumps blood into a forked artery. That splits the ventricle’s output into the pulmocutaneous circuit and the systemic circuit.

32. Amphibian Heart Problem: Oxygenated and deoxygenated blood mix in ventricle. Heart pumps out a mixture of oxy- and deoxygenated blood to peripheral tissues. Inefficient systemic circulation.

33. Reptile Heart Developed a partial septum (wall) between the ventricle. Partially separates oxy- and deoxygenated blood. Benefit: More efficient circulation; more active. Problem: Still a three-chambered heart with some mixing; incomplete separation.

35. Reptiles (Except Crocodilians) Reptiles have double circulation: With a pulmonary circuit (lungs) and a systemic circuit. Turtles, snakes, and lizards: Have a three-chambered heart

36. Enter the Crocodiles! Have complete separation of ventricles. First Four-chambered heart that separates oxy- and deoxygenated blood. Completely separate pulmonary and systemic circuits. Increased efficiency and more active.

37. A Very Active Saltwater Crocodile!

38. Mammal and Bird Hearts True Four-chambered hearts- separate systemic and pulmonary circuits. Can repump blood to body after return from lungs without mixing oxy- and deoxygenated blood. Double Pump: Right side = pulmonary circuit and Left Side = systemic circuit. Greater efficiency = higher metabolic rate, transport of heat and endothermy.

41. The mammalian cardiovascular system

42. The Mammalian Heart: A Closer Look

43. Vertebrate circulatory systems

44. What is the cardiovascular system? Three parts: Blood – a circulating fluid. Heart – a pump. Blood vessels – the conducting pipes.

45. Cardiovascular Lymphatic Systems Fluid leaves the vessel and enters the tissues- interstitial fluid. Eventually returns to the vessels. Lymphatic system has its own vessels. Used to transport antibodies, white blood cells, and monitor for infection and cancer. Cardiovascular + Lymphatic = Circulatory System.

50. The velocity of blood flow varies in the circulatory system: And is slowest in the capillary beds as a result of the high resistance and large total cross-sectional area.

51. Two mechanisms: Regulate the distribution of blood in capillary beds. In one mechanism- Contraction of the smooth muscle layer in the wall of an arteriole constricts the vessel.

52. In a second mechanism: Precapillary sphincters control the flow of blood between arterioles and venules.

55. Marine Mammals Limit heat loss by countercurrent flow- veins run parallel to an artery and carry heat back to core before arterial blood circulates to body’s surface. Walruses, seals, killer whales (Fig. 46.23)

56. What is blood? Specialized connective tissue with cells in a fluid matrix.

57. Functions of the Blood Transport dissolved gases, nutrients, hormones, and metabolic wastes. Regulation of the pH and electrolytes of interstitial fluid. Neutralizes the acids created by metabolism (lactic acid). Restricts fluid losses through damaged vessels or at injury sites- blood clots.

58. Functions of the Blood Defense against toxins and pathogens- transports white blood cells that migrate into tissue to fight infection and remove debris. Also, deliver antibodies. Stabilize body temperature- absorbs heat from active muscles and distributes to other tissues. Also brings heat to the surface of the skin to lose heat.

59. Composition of Blood It is a fluid connective tissue with an extracellular matrix- plasma + formed elements (cells and cell fragments) = whole blood. Plasma + Formed Elements = Whole Blood.

63. Plasma- The Fluid of Life! Plasma = Plasma Proteins + a Ground Substance (Serum). Plasma Proteins: Albumin- transport fatty acids, maintain isotonic solution. Globulin- immunoglobulin (antibodies). Fibrinogen- form blood clots; becomes fibrin- an insoluble protein.

65. Plasma- The Fluid of Life! Plasma that has been allowed to clot will lose its fibrin and other salts like Ca+2. Plasma without its fibrin – Serum.

66. Formed Elements Formed Elements = Blood Cells + Fragments suspended in the plasma. Erythrocytes (Red Blood Cells) – most abundant (99.9% of all cells); transport of oxygen and carbon dioxide. Leukocytes (White Blood Cells) – body’s defense cells. (0.1% of cells). Thrombocytes (Platelets) – small, membrane- bound packets of cytoplasm that contain enzymes for blood clot formation.

67. Erythrocyte

68. A Normal Blood Smear

69. Collecting and Analysis of Blood Blood usually collected at a vein-venipuncture. Venipuncture- veins are easy to locate, walls of vein are thinner, pressure is lower? heals easier. Peripheral capillaries- tip of finger, earlobe; oozing small drop for blood smear. Arterial Puncture- check for efficiency of gas exchange.

70. Properties of Blood Temperature- 38° C or 100.4°F. Viscosity- has a great deal of dissolved proteins in plasma ? more viscous than water. pH – 7.35-7.45; slightly alkaline.

71. Erythrocytes (RBCs) “erythros”- red; “cyte”- cell. RBCs are the most abundant blood cell (99.9%). 25 trillion in average adult. Takes ~ 1 min. to travel circuit. Hematocrit- percentage of formed elements in a sample of whole blood. # of cells / microliter of whole blood. Has a red pigment-hemoglobin- gives whole blood its color.

72. RBCs Structure and Function Highly specialized cell to transport gases. Cell structure is a biconcave disc.

73. EM of RBCs

74. RBCs Structure and Function Shape provides the RBC with a large surface area. Exchange of O2 with the surrounding plasma must be quick; larger surface area? faster the exchange. Total surface of all RBCs is 3800 m2 compared to 1.9 m2 of the whole human body.

75. RBCs Structure and Function Biconcave shape allows them to form stacks (dinner plates) – rouleaux inside narrow blood vessels. Rouleaux permit the cells to pass through blood vessels without bumping along the walls. Do not form logjams or clogs in the narrow capillary.

76. Rouleaux in a Blood Smear

77. Rouleaux in Bone Marrow

78. RBCs Structure and Function Biconcave shape allows the RBCs to bend and flex when entering capillaries. May pass through capillaries ½ the RBC’s diameter.

79. RBC’s are Highly Specialized Cells Have lost all organelles- lack nuclei, mitochondria, and ribosomes. Lost these structures to allow more space for hemoglobin and oxygen transport. Downside: RBCs unable to divide or repair themselves. Made in bone marrow. Short lifespan- 120 days and then must be broken down.

80. Hemoglobin (Hb) Accounts for 95% of proteins inside the RBC. 280 million Hbs in each RBC. Hb binds to and transports O2 and CO2.

83. Hb Molecule Each Hb molecule = four protein chains = 2 alpha chains + 2 beta chains of polypeptides. Each chain is a globular subunit and has a heme group. Heme – a porphyrin which is a ring compound with an iron in the center. Iron has a + charge and can bind to O2 (negative).

84. Hb Molecule When hemoglobin binds to O2 – it becomes oxyhemoglobin. Very weak interaction; easy to separate. Fetus uses a fetal hemoglobin- more readily binds to O2 for more efficient uptake from mother’s RBCs.

85. Hb Molecule Alpha and Beta chains bind to CO2 at other sites and transport to lungs. If hematocrit is low or the amount of Hb in RBCs is low than normal activity cannot be sustained in tissue- anemia.

87. Sickle Cell Anemia Mutations in the beta chains of the Hb molecule. When the blood contains abundant O2, the Hb and RBCs are normal. But when the defective Hb loses its O2, neighboring Hb molecules interact and change the shape of the cell- curved and stiff. Cannot form rouleaux and may form clots.

89. Sickle Cell Anemia

90. Iron-Deficiency Anemia

91. Malaria in an RBC

92. Leukocytes (WBCs) General Properties: 1. Help defend against pathogens, toxins, and damaged cells. 2. They have nuclei and other organelles. 3. Are made in bone marrow, thymus, spleen, and other lymphatic tissue.

94. Two Major Groups of WBCs Granulocytes- WBCs with darkly-staining vesicles and lysosomes inside. a. Neutrophils b. Eosinophils c. Basophils

95. Two Major Groups of WBCs Agranulocytes- do not stain darkly on their interior; have very small vesicles and lysosomes. a. Monocytes b. Lymphocytes

96. Leukocytes Most WBCs are not in the circulatory system, but in tissues or organs of the lymphatic system. Circulate for only a short time in vessels.

97. Characteristics of WBCs Move along the capillaries by amoeboid movement. Detect chemicals from injured cells. Leave the capillary by squeezing through cells –diapedesis. Are positively chemotactic in the tissue. Can destroy things by phagocytosis.

98. Ameboid Movement and Phagocytosis

100. Neutrophils Most abundant of WBCs. Granules are neutral. Filled with toxins. Have a dense, segmented nucleus of 2 to 5 lobes- Polymorphonuclear (PMNs). Very mobile and arrive at site of infection first.

101. Neutrophils Phagocytize “tagged” bacteria. Breakdown bacteria with their toxic granules. Also, release chemicals to call WBCs to the site- interleukins.

102. Neutrophils

103. Eosinophiles Granules stain with eosin- a red dye. Only amount 2-4 % of the WBCs. Have a bilobed nucleus. Phagocytize bacteria and cell debris. Use exocytosis to release toxins onto the surface of large parasites. Release chemicals that cause allergic reactions.

104. Eosinophil

105. Neutrophil and Eosinophil

106. Basophiles Stain very darkly. Very small cells. Very rare in circulation. Usually in tissue. Release granules of histamine and heparin. Histamine = permeability of capillaries. Heparin = blood clotting. Do not phagocytize.

107. Basophil

108. The Last Type of Phil

109. Monocytes Larger cells with oval nuclei. Circulate throughout the blood stream. Leave the vessel and become macrophages. Macrophages phagocytize bacteria, cell debris, and other foreign elements. Also, release chemical messengers.

110. Monocyte

111. Lymphocytes Larger than RBCs and lack deeply-stained granules. Single, large nucleus. Abundant in blood. Migrate from blood ? to tissue? through lymph? return to blood. Most are not found in blood at any one time.

112. Lymphocyte

113. 3 Kinds of Lymphocytes T Cells: cellular immunity against foreign tissue and cells infected with viruses; have killer T cells and helper T cells (CD-4 and CD-8). B cells: humoral immunity, produce antibodies (globulin proteins).Also memory cells. NK cells: (Natural Killers) large granules of toxin that destroy cancerous cells and some virally-infected cells.

114. Leukemia

115. Platelets Called thrombocytes in nonmammals. Circulate for 9-12 days. Platelets are only cell fragments in mammals.

116. Platelet Function Transport of proteins and enzymes important to the clotting process.

117. Platelet Function Active contraction after clot formation has occurred. Contain actin & myosin. After clot forms contraction shrinks clot & reduces size of break in vessel wall

118. Platelet Function Formation of a temporary patch in the walls of damaged blood vessels. Forms a platelet plug: slows the rate of blood loss while clotting continues.

119. Blood Clot

120. Platelet Production Thrombocytopoiesis occurs in the bone marrow. Bone marrow contains: Megakaryocytes: enormous w/ large nuclei.

121. Platelet Production Megakaryocytes make proteins, enzymes, & membranes. Shed cytoplasm in small membrane-enclosed packets: Platelets that enter circulation. Mature megakaryocyte produces 4000 platelets.

122. Megakaryocyte

123. What happens when we have an allergic reaction? Can allergies kill? An Application Video: Discovery-Body Story- Allergies