Circulatory Systems AP Biology 2008 2009 Exchange of

Circulatory Systems AP Biology 2008 -2009

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

Overcoming limitations of diffusion § Diffusion is not adequate for moving material across more than 1 -cell barrier CO 2 aa O 2 CH aa CO 2 CHO NH 3 CH AP Biology CO 2 CHO O 2 aa aa O 2 aa CH NH 3 CO 2 NH 3 O 2 NH 3 CO 2 NH 3 CO 2 aa CHO

In circulation… § What needs to be transported u nutrients & fuels § from digestive system u respiratory gases § O 2 & CO 2 u intracellular waste w water, salts, nitrogenous wastes (urea) u protective agents § immune defenses w white blood cells & antibodies § blood clotting agents u regulatory molecules § hormones AP Biology

Open circulatory system § Taxonomy u invertebrates § insects, arthropods, mollusks § Structure u no separation between blood & interstitial fluid § hemolymph AP Biology

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

Vertebrate circulatory system § Adaptations in closed system u 2 low pressure to body number of heart chambers differs 3 4 low O 2 to body high pressure & high O 2 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 u increase body size § bigger body = bigger stomach for herbivores u endothermy § can colonize more habitats u flight § decrease predation & increase prey capture § Effect of higher metabolic rate u greater need for energy, fuels, O 2, waste removal § endothermic animals need 10 x energy AP Biology convergent evolution

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

Blood vessels arteries veins artery venules arterioles capillaries venules veins AP Biology

Arteries: Built for high pressure pump § Arteries u thicker walls § provide strength for high pressure pumping of blood narrower diameter u elasticity u § elastic recoil helps maintain blood pressure even when heart relaxes AP Biology

Veins: Built for low pressure flow Blood flows toward heart § Veins thinner-walled u wider diameter u Open valve § blood travels back to heart at low velocity & pressure § lower pressure w distant from heart w blood must flow by skeletal muscle contractions when we move Closed valve n squeeze blood through veins u valves § in larger veins one-way valves allow blood to flow only toward heart AP Biology

Capillaries: Built for exchange § Capillaries u very thin walls § lack 2 outer wall layers § only endothelium w enhances exchange across capillary u diffusion § exchange between blood & cells AP Biology

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? AP Biology sphincters open sphincters closed

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

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

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

Mammalian circulation systemic pulmonary systemic AP Biology What do blue vs. red areas represent?

Mammalian heart Coronary arteries AP Biology to neck & head & arms

Coronary arteries bypass surgery AP Biology

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

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

Cardiac cycle § 1 complete sequence of pumping heart contracts & pumps u heart relaxes & chambers fill u contraction phase u § systole § ventricles pumps blood out u relaxation phase § diastole § atria refill with blood systolic ____ AP Biology diastolic pump (peak pressure) _________ fill (minimum pressure) 110 ____ 70

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) AP Biology

Blood pressure § Maintained by elastic recoil in arteries § Dissipated by resistance in narrow § arteries Regulated by: -vasoconstriction & vasodilation -cardiac output AP Biology

AP Biology

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 p. H 6. 8 to 7. 4 Regulation of Body Fluid Electrolytes and osmotic balance AP Biology

Components of blood- plasma and formed elements Component Scientific name Plasma Red blood cells properties Mostly water, plasma proteins, dissolved nutrients, wastes, ions, and hormones, and heat erythrocytes Biconcave disc. Made of red Hgb is pigment that carries O 2, CO 2 -Hgb is Protein, with an Fe core -low blood o 2 erythropoietin horm released stim bone marrow RBC increase O 2 White blood leukocytes cells Immunity and defense from infection Large cells, large darkly staining nuclei platelets Tiny thin walled bags containing thromboplastin that cause CLOTTING AP Biology thrombocytes

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 p. p. thrombin fibrinogen (soluble) p. p. a CLOT AP Biology Fibrin mesh=clot fibrin (insoluble mesh) that gets plugged with RBC’s making

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 AP Biology