Circulatory Systems and Exchange of Materials in Animal Cells

Slide1AP Biology2008-2009 Circulatory Systems

Slide2AP Biology

Slide3AP BiologyExchange of materials  Animal cells exchange material across their cell membrane  fuels for energy  nutrients  oxygen  waste (urea, CO 2 )  If you are a 1-cell organism that’s easy!  diffusion  If you are many-celled that’s harder

Slide4AP BiologyOvercoming limitations of diffusion O 2 CHO CHO aa aa CH CO 2 NH 3 aa O 2 CH aa CO 2 CO 2 CO 2 CO 2 CO 2 CO 2 CO 2 CO 2 CO 2 CO 2 NH 3 NH 3 NH 3 NH 3 NH 3 NH 3 NH 3 NH 3 O 2 aa CH aa CHO O 2  Diffusion is not adequate for moving material across more than 1-cell barrier

Slide5AP BiologyIn circulation…  What needs to be transported  nutrients & fuels  from digestive system  respiratory gases  O 2  & CO 2  from & to gas exchange systems: lungs, gills  intracellular waste  waste products from cells  water, salts, nitrogenous wastes (urea)  protective agents  immune defenses  white blood cells  &  antibodies  blood clotting agents  regulatory molecules  hormones

Slide6AP BiologyCirculatory systems  All animals have:  circulatory fluid =  “ blood ”  tubes =  blood vessels  muscular pump =  heart open closed hemolymph blood

Slide7AP BiologyOpen circulatory system  Taxonomy  invertebrates  insects, arthropods, mollusks  Structure  no separation between blood & interstitial  fluid  hemolymph

Slide8AP BiologyClosed circulatory system  Taxonomy  invertebrates  earthworms, squid, octopuses  vertebrates  Structure  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 pressures

Slide9AP BiologyVertebrate circulatory system  Adaptations in closed system  number of heart chambers differs 4 chamber heart is double pump = separates oxygen-rich & oxygen-poor blood; maintains high pressure What’s the adaptive value of a 4 chamber heart? 2 3 4 low pressure to body low O 2 to body high pressure & high O 2 to body

Slide10AP BiologyEvolution of vertebrate circulatory system fish amphibian reptiles birds & mammals A A V V V V V A A A A A V 2 chamber 3 chamber 3 chamber 4 chamber

Slide11AP BiologyEvolution of 4-chambered heart convergent evolution  Selective forces  increase  body size  protection from predation  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, O 2 , waste removal  endothermic animals need 10x energy  need to deliver 10x fuel & O 2  to cells

Slide12AP BiologyVertebrate 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

Slide13AP BiologyArteries: 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

Slide14AP BiologyVeins: Built for low pressure flow  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 valves allow blood to flow only toward heart Open   valve Blood flows toward heart Closed valve

Slide15AP BiologyCapillaries: Built for exchange  Capillaries  very thin walls  lack 2 outer wall layers  only endothelium  enhances exchange across capillary  diffusion  exchange between blood & cells

Slide16AP BiologyControlling 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  capillaries in  brain ,  heart ,  kidneys  &  liver  usually filled to capacity sphincters  open sphincters  closed

Slide17AP BiologyExchange across capillary walls Arteriole Blood flow Venule Lymphatic capillary Interstitial fluid Fluid & solutes flows out of capillaries to tissues due to  blood pressure   “bulk flow” Interstitial fluid flows back into capillaries due to  osmosis   plasma proteins    osmotic    pressure in capillary BP > OP BP < OP 15% fluid returns via lymph 85% fluid returns to capillaries Capillary

Slide18AP BiologyLymphatic 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

Slide19AP BiologyLymph system Production & transport of WBCs Traps foreign invaders lymph node lymph vessels (intertwined amongst blood vessels)

Slide20AP BiologyMammalian circulation What do  blue   vs.   red   areas represent? What do  blue   vs.   red   areas represent? pulmonary systemic systemic

Slide21AP BiologyMammalian heart Coronary arteries to neck & head & arms

Slide22AP BiologyCoronary arteries bypass surgery

Slide23AP BiologyAV SL 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”

Slide24AP BiologyAV SL AV 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

Slide25AP BiologyCardiac cycle systolic ________ diastolic pump   (peak pressure) _________________ fill   (minimum pressure)  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 110 ____ 70

Slide26AP BiologyMeasurement of blood pressure  High Blood Pressure (hypertension)  if top number ( systolic  pumping) > 150  if bottom number ( diastolic  filling) > 90