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AP Biology Circulatory Systems AP Biology AP Biology Exchange of materials Animal cells exchange material across Overcoming limitations of diffusion Diffusion is not adequate for moving their cell membrane fuels for energy nutrients oxygen waste (urea, CO2) material across more than 1-cell barrier If you are a 1-cell organism that’s easy! AP Biology aa aa CO2 CHO NH3 CHO CH O2 aa aa O2 aa NH3 CO2 CO2 CO2 NH3 NH3 CO2 CH NH3 NH3 CO2 CO2 NH3 O2 NH3 NH3 CO2 O2 CH diffusion If you are many-celled that’s harder CO2 CO2 CHO CO2 aa AP Biology 1 AP Biology In circulation… What needs to be transported Circulatory systems All animals have: nutrients & fuels circulatory fluid = “blood” tubes = blood vessels muscular pump = heart from digestive system respiratory gases intracellular waste O2 & CO2 from & to gas exchange systems: lungs, gills open closed waste products from cells water, salts, nitrogenous wastes (urea) protective agents immune defenses white blood cells & antibodies blood clotting agents regulatory molecules hormones AP Biology Open circulatory system Taxonomy invertebrates hemolymph AP Biology Closed circulatory system Taxonomy Structure closed system = higher pressures invertebrates earthworms, squid, octopuses insects, arthropods, mollusks blood vertebrates Structure no separation between blood & interstitial fluid blood confined to vessels & separate from interstitial fluid 1 or more hearts large vessels to smaller vessels hemolymph material diffuses between blood vessels & interstitial fluid AP Biology AP Biology 2 AP Biology Vertebrate circulatory system Adaptations in closed system 2 Evolution of vertebrate circulatory system number of heart chambers differs 3 4 fish 2 chamber low pressure to body high pressure & high O2 to body low O2 to body What’s the adaptive value of a 4 chamber heart? 4 chamber heart is double pump = separates oxygen-rich & AP Biology oxygen-poor blood; maintains high pressure Evolution of 4-chambered heart Selective forces increase body size Birds AND mammals! Wassssup?! V A A V A V A V AP Biology Vertebrate cardiovascular system Chambered heart arteries = carry blood away from heart arterioles decrease predation & increase prey capture veins = return blood to heart capillaries = thin wall, exchange / diffusion Effect of higher metabolic rate endothermic animals need 10x energy AP Biology need to deliver 10x fuel & O2 to cells A V V flight greater need for energy, fuels, O2, waste removal A A Blood vessels endothermy can colonize more habitats birds & mammals 4 chamber atrium = receive blood ventricle = pump blood out herbivores reptiles 3 chamber protection from predation bigger body = bigger stomach for amphibian 3 chamber venules convergent evolution capillary beds = networks of capillaries AP Biology 3 AP Biology Blood vessels arteries veins artery Arteries: Built for high pressure pump Arteries arterioles provide strength for high venules pressure pumping of blood arterioles capillaries venules AP Biology maintain blood pressure even when heart relaxes AP Biology Veins: Built for low pressure flow Blood flows toward heart Veins thinner-walled wider diameter Open valve Capillaries: Built for exchange Capillaries only endothelium enhances exchange at low velocity & pressure lower pressure distant from heart blood must flow by skeletal muscle very thin walls lack 2 outer wall layers blood travels back to heart across capillary contractions when we move Closed valve squeeze blood through veins narrower diameter elasticity elastic recoil helps veins thicker walls diffusion exchange between blood & cells valves in larger veins one-way valves allow blood to flow only toward heart AP Biology AP Biology 4 AP Biology Controlling blood flow to tissues Blood flow in capillaries controlled by Exchange across capillary walls after a meal, blood supply to digestive tract increases Fluid & solutes flows out of capillaries to tissues due to blood pressure during strenuous exercise, blood is diverted from “bulk flow” pre-capillary sphincters supply varies as blood is needed digestive tract to skeletal muscles Why? Lymphatic capillary Interstitial fluid flows back into capillaries due to osmosis plasma proteins ↑ osmotic pressure in capillary BP > OP BP < OP Interstitial fluid capillaries in brain, heart, kidneys & liver usually filled to capacity What about edema? Blood flow 85% fluid returns to capillaries Capillary AP Biology sphincters open Lymphatic system sphincters closed AP Biology 15% fluid returns via lymph Arteriole Lymph system Venule Production & transport of WBCs Traps foreign invaders Parallel circulatory system transports white blood cells collects interstitial fluid & returns to blood defending against infection lymph vessels maintains volume & protein concentration of blood drains into circulatory system near junction of vena cava & right atrium (intertwined amongst blood vessels) lymph node AP Biology AP Biology 5 AP Biology Mammalian circulation systemic Mammalian heart to neck & head & arms pulmonary Coronary arteries systemic AP Biology What do blue vs. red areas represent? Coronary arteries AP Biology Heart valves 4 valves in the heart bypass surgery flaps of connective tissue prevent backflow SL Atrioventricular (AV) valve between atrium & ventricle keeps blood from flowing back into atria when ventricles contract AV AV “lub” Semilunar valves between ventricle & arteries prevent backflow from arteries into ventricles while they are relaxing “dub” AP Biology AP Biology 6 AP Biology Lub-dub, lub-dub Heart sounds Cardiac cycle 1 complete sequence of pumping closing of valves “Lub” recoil of blood against closed AV valves “Dub” heart contracts & pumps heart relaxes & chambers fill contraction phase SL AV systole ventricles pumps blood out AV recoil of blood against semilunar valves diastole atria refill with blood Heart murmur defect in valves causes hissing sound when stream of blood squirts backward through valve AP Biology relaxation phase systolic ________ AP Biology diastolic pump (peak pressure) _________________ fill (minimum pressure) 110 ____ 70 Measurement of blood pressure Bloody well ask some questions, already! High Blood Pressure (hypertension) if top number (systolic pumping) > 150 AP Biology if bottom number (diastolic filling) > 90 AP Biology 7
