Circulatory System AP Biology Exchange of materials Animal

Circulatory System AP Biology

Exchange of materials § Animal cells exchange material across their cell membrane u u Fuel: _____________ Nutrients: ___________ Oxygen: ____________ Waste: _____________ § If you are a 1 -cell organism that’s easy! u ____________________ § If you are many-celled that’s harder!

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 CHO CH 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 from & to gas exchange systems: lungs, gills u intracellular waste § waste products from cells w water, salts, nitrogenous wastes (urea) u protective agents § immune defenses w white blood cells & antibodies § blood clotting agents u regulatory molecules § hormones § buffers

Thermoregulation § Vasodilation & vasoconstriction u u adjusts blood flow evaporative cooling Vasoconstriction Vasodilation

Temperature management Countercurrent heat exchange

The basic circulatory system § All animals have: circulatory fluid u tubes u muscular pump u

Open circulatory system Who? § _________ § i. e. Arthropoda and most Mollusca § Structure u no separation between blood & interstitial fluid § hemolymph

Closed circulatory system § Taxonomy u Some Invertebrata § Annelida and Cephalopoda u All Vertebrata § Structure u blood confined to vessels & separate from interstitial fluid § 1 or more hearts § large vessels to smaller vessels § material diffuses between blood vessels & interstitial fluid closed system = higher pressure

Blood & blood cells § Blood is a tissue of cells in a fluid u ________ = fluid (55% of volume) § ions (electrolytes), plasma proteins, nutrients, waste products, gases, hormones u ________ = (45% of volume) § Erythrocytes: _________ w Function: _________ § Leukocytes: _________ w defense § Platelets w Function: _________

Components of Blood tissue

Blood cell production § Stem cells pluripotent cells u in bone marrow u produce all types of blood cells u cells differentiate in bone marrow & lymph tissue u

Red blood cells § Function u O 2 transport § Structure u small biconcave disks § large surface area u lack nuclei & mitochondria 5 liters of blood in body = 25 trillion RBC § more space for haemoglobin w iron-containing protein that transports O 2 § generate ATP by anaerobic respiration w only last 3 -4 months (120 days) w ingested by phagocytic cells in liver & spleen w ~3 million RBC destroyed each second w produce ~3 million RBC every second to replace

Hemoglobin § Protein with 4° structure u O 2 carrier molecule 250, 000 molecules hemoglobin/RBC § each Hb molecule carries 4 O 2 § each RBC carries 1 million O 2

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 & oxygen-poor blood; maintains high pressure

Evolution of vertebrate circulatory system fish 2 chamber V amphibian 3 chamber reptiles 3 chamber A A V A V birds & mammals 4 chamber A V

Evolution of 4 -chambered heart § Selective forces u increase body size § protection from predation § 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 § need to deliver 10 x fuel & O 2 to cells

Vertebrate cardiovascular system § 4 -chambered heart, separated by a septum u u atrium = receive blood ventricle = pump blood out § Blood vessels u ________= carry blood away from heart arterioles u ________= return blood to heart venules u capillaries = thin wall, exchange / diffusion § capillary beds = networks of capillaries

Blood vessels arteries veins artery venules arterioles capillaries venules veins

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

Veins: Built for low pressure flow § Veins Blood flows thinner-walled u wider diameter toward heart 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 n squeeze blood through veins Closed valve u Valves (animation) § in larger veins one-way valves allow blood to flow only toward heart

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

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 u capillaries in brain, heart, kidneys & liver usually filled to capacity sphincters open sphincters closed

Exchange across capillary walls (animation) Fluid & solutes flows out of capillaries to tissues due to blood pressure Lymphatic capillary Interstitial fluid flows back into capillaries due to osmosis § plasma proteins osmotic pressure in capillary § “bulk flow” BP > OP BP < OP Interstitial fluid Blood flow 90% fluid returns to capillaries Capillary Arteriole 10% 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

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

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

Gas Exchange animation

Mammalian heart to neck & head & arms

Coronary arteries Link: CABG (“cabbage”)

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

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 (audio) u u defect in valves causes hissing sound when stream of blood squirts backward through valve Mitrial valve: normal and defective

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

Measurement of blood pressure § High Blood Pressure (hypertension) u if top number (systolic pumping) > 150 u if bottom number (diastolic filling) > 90

Control of heart § Evolution of system to control heart beat timely delivery of O 2 to cells is critical u cells of cardiac muscle are “self-excitatory” u § contract without any signal from nervous system § each cell has its own contraction rhythm, so have to coordinate them u cells synchronized by sinoatrial (SA) node § “pacemaker” § cells in wall of right atrium § sets rate & timing of cardiac cell contraction

SA node & Electrical signals (animation) § Pacemaker generates electrical impulses across heart u signal also transmitted to skin = EKG or ECG allows atria to empty completely before ventricles contract stimulates ventricles to contract from bottom to top, driving blood into arteries

Regulation of heart rate § Physiological cues affect heart rate u nervous system § speed up pacemaker § slow down pacemaker § heart rate is compromise regulated by opposing actions of these 2 sets of nerves u hormones § epinephrine from adrenal glands increases heart rate body temperature u activity u § exercise, etc.

Cardiovascular disease § Leading cause of death in U. S. u plaques develop in inner wall of arteries § narrowing channel u stroke, heart attack, atherosclerosis, arteriosclerosis, hypertension (high blood pressure) § tendency inherited, but other risk factors: smoking, lack of exercise, obesity, diet rich in fat

Cardiovascular health (U. S. 2001) Heart Disease 696, 947 Cancer 557, 271 Stroke 162, 672 Chronic lower respiratory diseases 124, 816 Accidents (unintentional 106, 742 injuries) Diabetes 73, 249 Influenza/Pneumonia 65, 681 Alzheimer's disease 58, 866 Nephritis, nephrotic syndrome & nephrosis 40, 974 Septicemia 33, 865

Women & Heart Disease Death rates for heart disease per 100, 000 women, 2002 Risk factors § Smoking § Lack of exercise § High fat diet § Overweight § Heart disease is 3 rd leading cause of death among women aged 25– 44 years & 2 nd leading cause of death among women aged 45– 64 years.