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Chapter 42

Chapter 42. Circulatory System. Learning Objectives. TBD. Invertebrates with No Circulatory Systems. Simple invertebrates: sponges, cnidarians, and flatworms. Animal Circulatory Systems. Muscular heart pumps specialized fluid (such as blood ) through tubular vessels Blood

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Chapter 42

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  1. Chapter 42 Circulatory System

  2. Learning Objectives • TBD

  3. Invertebrates with No Circulatory Systems • Simple invertebrates: sponges, cnidarians, and flatworms

  4. Animal Circulatory Systems • Muscular heart pumps specialized fluid (such as blood) through tubular vessels • Blood • Carries O2 and nutrients to body tissues • Carries away CO2 and wastes

  5. Open and Closed Circulatory Systems • Open circulatory system • In most invertebrates • Heart pumps hemolymph into vessels that empty into body spaces (sinuses) before returning to the heart • Closed circulatory system • In some invertebrates and all vertebrates • Blood is confined in blood vessels throughout the body (does not mix with interstitial fluid)

  6. Open and Closed Circulatory Systems

  7. Invertebrate Circulatory Systems • Open circulatory systems occur in arthropods and most mollusks • Closed circulatory systems occur in annelids and in mollusks such as squids and octopuses

  8. Vertebrate Circulatory Systems • Evolved from a heart with a single series of chambers (single circuit) to a double heart that pumps blood through separate pulmonary and systemic circuits

  9. d. Circulatory system of crocodilians, birds, and mammals Lung capillaries PULMONARY CIRCUIT Right atrium Left atrium Left ventricle Right ventricle SYSTEMIC CIRCUIT Capillary networks in other body tissues In the four-chambered heart of crocodilians, birds, and mammals, a complete septum forms two ventricles and keeps the flow of oxygenated blood from the lungs and deoxygenated blood entirely separate from the rest of the body. Fig. 42.5d, p. 952

  10. 42.2 Blood and Its Components • Plasma is an aqueous solution of proteins, ions, nutrient molecules, and gases • Erythrocytes are the oxygen carriers of the blood • Leukocytes provide the body’s front line of defense against disease • Platelets induce blood clots that seal breaks in the circulatory system

  11. Mammalian Blood • A fluid connective tissue • Blood cells (erythrocytes, leukocytes, platelets) • Suspended in a fluid matrix (plasma)

  12. Plasma and Plasma Proteins • Contains water, ions, dissolved gases (O2 and CO2), glucose, amino acids, lipids, vitamins, hormones, and plasma proteins • Plasma proteins • Albumins (transport, osmotic balance, pH) • Globulins (transport, immunoglobins) • Fibrinogen (blood clotting)

  13. Blood Cells • Erythrocytes • Contain hemoglobin (transports O2 from lungs to body) • Leukocytes • Defend body against infecting pathogens • Platelets • Functional cell fragments that trigger clotting

  14. Erythrocyte (red blood cell) Leukocyte (white blood cell) Platelets Fig. 42.6a, p. 954

  15. Plasma Leukocytes and platelets Packed cell volume, or hematocrit Erythrocytes Fig. 42.6b, p. 954

  16. Fig. 42.6c, p. 954

  17. Leukocytes Monocyte/macrophage Eosinophil B lymphocyte Basophil T lymphocyte Platelets Neutrophil megakaryocyte Erythrocyte Natural killer (NK) cell Lymphoid stem cell Myeloid stem cell (marrow) (lymph) Pluripotent stem cell Fig. 42.7, p. 955

  18. Types of Defense • Non-specific • Specific (antibody-mediated)

  19. Bacteria at injury site 1 Macrophages Mast cells 5 Cytokines Capillary Neutrophils Chemokines 2 Histamine 4 3 Neutrophils sticking to wall Endothelial cell of capillary 1. A break in the skin introduces bacteria. 2. Activated mast cells release histamine. 3. Histamine and cytokines dilate local blood vessels. 4. Chemokines attract neutrophils, which pass between cells of the blood vessel wall. 5 Neutrophils engulf the pathogens and destroy them. Fig. 43.1, p. 974

  20. Adaptive (Acquired) Immunity • Triggered by antigens • Exogenous or endogenous macromolecules (proteins or polysaccharides) • Recognized by B cells and T cells via antibodies • Targets particular pathogens or toxin molecules

  21. Light and Heavy Polypeptide Chains in an Antibody Molecule

  22. b. Agglutination Antibody Antigen Bacterium Fig. 43.11b, p. 985

  23. Immunological Memory • First encounter with an antigen elicits a primary immune response • Later exposure to the same antigen elicits a rapid secondary immune response with a greater production of antibodies

  24. The Mammalian Heart • A four-chambered pump • Two atria at top of heart • Two ventricles at bottom of heart • Atrioventricular (AV) valves between atria and ventricles • Semilunar (SL) valves between ventricles and aorta / pulmonary arteries • Blood is pumped into two separate circuits • Pulmonary circuit (right heart)- to the lungs • Systemic circuit (left heart)- to the body

  25. Blood Vessels • Blood leaves the heart in large arteries • Branch into smaller arterioles • Arterioles deliver blood to capillary networks • Capillaries exchange substances between blood and interstitial fluid • Small venules collect blood from capillaries • Join into larger veins that return blood to heart

  26. To systemic circuit To body Aorta Pulmonary arteries (to lungs) VC-from body Superior vena cava (returns blood from head, upper limbs) Left pulmonary veins (return blood from lungs)From pulmonary circuit Right pulmonary veins (return blood from lungs) PV Right atrium Left atrium AV AV (MV) valve (shown open) AV (TV) Valve (shown open) Left ventricle Right ventricle Septum Inferior vena cava (returns blood flow from trunk, legs) KEY Semilunar (SL) valves Atrioventricular (AV) valves To systemic circuit Fig. 42-9, p. 957

  27. systemic circuit Capillary networks of head and forelimbs Superior vena cava Pulmonary artery Pulmonary artery pulmonary circuit pulmonary circuit Aorta LA RA LV RV Capillary network of right lung Capillary network of left lung Pulmonary vein Pulmonary vein Inferior vena cava To lower body parts Capillary networks of abdominal organs and lower limbs systemic circuit Fig. 42.10, p. 958

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