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Circulatory Systems

This text discusses the exchange of materials in animal cells, including nutrients, fuels, oxygen, and waste products. It explains the limitations of diffusion and the need for circulatory systems to transport these materials. It also explores the structures and functions of different circulatory systems, such as open and closed systems, invertebrate and vertebrate systems, and the adaptations of the vertebrate cardiovascular system. The text further explains the role of blood vessels, the importance of valves in the heart, and the functions of the lymphatic system.

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Circulatory Systems

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  1. Circulatory Systems

  2. Exchange of materials • Animal cells exchange material across their cell membrane • fuels for energy • nutrients • oxygen • waste (urea, CO2) • If you are a 1-cell organism that’s easy! • diffusion • If you are many-celled that’s harder

  3. CO2 CO2 O2 NH3 aa NH3 CO2 NH3 CO2 CO2 NH3 O2 NH3 CO2 CO2 CO2 aa NH3 NH3 NH3 CHO CO2 CO2 aa CH Overcoming limitations of diffusion • Diffusion is not adequate for moving material across more than 1-cell barrier aa O2 CH CHO CO2 aa NH3 CHO CH O2 aa

  4. In circulation… • What needs to be transported • nutrients & fuels • from digestive system • respiratory gases • O2 & CO2 • intracellular waste • water, salts, nitrogenous wastes (urea) • protective agents • immune defenses • white blood cells & antibodies • blood clotting agents • regulatory molecules • hormones

  5. Open circulatory system • Taxonomy • invertebrates • insects, arthropods, mollusks • Structure • no separation between blood & interstitial fluid • hemolymph

  6. Closed circulatory system closed system = higher pressures • Taxonomy • invertebrates • earthworms, squid, octopuses • vertebrates • Structure • blood confined to vessels & separate from interstitial fluid • 1 or more hearts • material diffuses between blood vessels & interstitial fluid

  7. Vertebrate circulatory system • Adaptations in closed system • number of heart chambers differs 2 3 4 high pressure & high O2to body low pressureto body low O2to body What’s the adaptive value of a 4 chamber heart? 4 chamber heart is double pump = separates oxygen-rich & oxygen-poor blood; maintains high pressure

  8. Evolution of 4-chambered heart • Selective forces • increase body size • bigger body = bigger stomach for herbivores • endothermy • can colonize more habitats • flight • decrease predation & increase prey capture • Effect of higher metabolic rate • greater need for energy, fuels, O2, waste removal • endothermic animals need 10x energy convergentevolution

  9. Vertebrate cardiovascular system • Chambered heart • atrium = receive blood • ventricle = pump blood out • Blood vessels • arteries = carry blood away from heart • arterioles • veins = return blood to heart • venules • capillaries = thin wall, exchange / diffusion • capillary beds = networks of capillaries

  10. Blood vessels arteries veins artery arterioles venules arterioles capillaries venules veins

  11. Arteries: Built for high pressure pump • Arteries • thicker walls • provide strength for high pressure pumping of blood • narrower diameter • elasticity • elastic recoil helps maintain blood pressure even when heart relaxes

  12. Veins: Built for low pressure flow Blood flows toward heart • Veins • thinner-walled • wider diameter • blood travels back to heart at low velocity & pressure • lower pressure • distant from heart • blood must flow by skeletal muscle contractions when we move • squeeze blood through veins • valves • in larger veins one-way valvesallow blood to flow only toward heart Openvalve Closed valve

  13. Capillaries: Built for exchange • Capillaries • very thin walls • lack 2 outer wall layers • only endothelium • enhances exchange across capillary • diffusion • exchange between blood & cells

  14. Controlling blood flow to tissues • Blood flow in capillaries controlled by pre-capillary sphincters • supply varies as blood is needed • after a meal, blood supply to digestive tract increases • during strenuous exercise, blood is diverted from digestive tract to skeletal muscles Why? sphincters open sphincters closed

  15. Exchange across capillary walls Lymphatic capillary Fluid & solutes flows out of capillaries to tissues due to blood pressure • Interstitial fluid flows back into capillaries due to osmosis BP > OP BP < OP Interstitial fluid Blood flow 85% fluid returns to capillaries Capillary 15% fluid returns via lymph Arteriole Venule

  16. Lymphatic system • Parallel circulatory system • transports white blood cells • defending against infection • collects interstitial fluid & returns to blood • maintains volume & protein concentration of blood • drains into circulatory system near junction of vena cava & right atrium

  17. Production & transport of WBCs Traps foreign invaders Lymph system lymph vessels (intertwined amongst blood vessels) lymph node

  18. systemic Mammaliancirculation pulmonary systemic What do bluevs.redareas represent?

  19. Mammalian heart to neck & head& arms Coronary arteries

  20. Coronary arteries bypass surgery

  21. SL AV AV Heart valves • 4 valves in the heart • flaps of connective tissue • prevent backflow • Atrioventricular (AV) valve • between atrium & ventricle • keeps blood from flowing back into atria when ventricles contract • “lub” • Semilunar valves • between ventricle & arteries • prevent backflow from arteries into ventricles while they are relaxing • “dub”

  22. Lub-dub, lub-dub • Heart sounds • closing of valves • “Lub” • recoil of blood against closed AV valves • “Dub” • recoil of blood against semilunar valves • Heart murmur • defect in valves causes hissing sound when stream of blood squirts backward through valve SL AV AV

  23. 110 ____ 70 systolic ________ diastolic pump(peak pressure) _________________ fill(minimum pressure) Cardiac cycle • 1 complete sequence of pumping • heart contracts & pumps • heart relaxes & chambers fill • contraction phase • systole • ventricles pumps blood out • relaxation phase • diastole • atria refill with blood

  24. Blood flow velocity • Determined by cross sectional area of vessels • FAST in large vessels (big but very few of them) • SLOW in capillaries (tiny vessels but many of them)

  25. Blood pressure • Maintained by elastic recoil in arteries • Dissipated by resistance in narrow arteries • Regulated by: -vasoconstriction & vasodilation -cardiac output

  26. Functions of the blood Transport • Dissolved gases (e.g. oxygen, carbon dioxide); • Waste products (e.g. water, urea); • Hormones; • Enzymes; • Nutrients • Plasma proteins such as blood-clotting and antibodies • Blood cells Maintains Body Temperature -distributes heat Controls pH 6.8 to 7.4 Regulation of Body Fluid Electrolytes and osmotic balance

  27. Components of blood- plasma and formed elements

  28. The clotting sequence platelet = thrombocyte • Torn blood vessel with ragged edges rips open thin walled thrombocytes passing by. • THROMBOPLASTIN released from platelet and starts the cascade Prothrombin thrombin p.p. fibrinogen fibrin (soluble) (insoluble p.p. mesh) that gets plugged with RBC’s  making a CLOT Fibrin mesh=clot

  29. Sinoatrial node produces an electrical stimulation on its own • Impulse then spreads In all directions through atria causing contraction • Impulses reach AV node, which causes ventricles to contract

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