Circulation and Gas Exchange

1. Circulation and Gas Exchange Chapter 42

2. Diffusion is not enough transport materials in an organism. Transport systems connect organs of exchange with the cells that need the materials. Invertebrates have a gastrovascular cavity or a circulatory system for internal transport. Open vs. Closed systems Vertebrate adaptations of the CV system Pumping cycle of the heart in mammals The cardiac cycle and maintaining the heart’s rhythmic beat Structure of Arteries, Veins and Capillaries and functions Movement of blood flow through pipes and blood pressure. The lymphatic system Blood as a tissue and clotting Gas Exchange systems: Gills, Tracheal systems, Lungs Mammalian respiratory system CO2 Transport in blood Summary of Key Ideas

3. Diffusion is not enough transport materials in an organism. • 1 second for glucose to travel 100 um • 100 seconds to diffuse 1 mm. • Three hours to travel 1 cm. WAY TOO SLOW!!!!! Therefore mechanisms of transport must be in place.

4. Transport systems connect organs of exchange with the cells that need the materials. • Gastrovascular cavities: Body wall of the digestive cavity is only two cells thick. • The GV cavity is very spread out over the entire animal. • Therefore digestion occurs followed by immediate diffusion and distribution to the surrounding cells in the tissues.

5. Internal Transport is accomplished in the Gastrovascular cavity of Cnidarians

6. Open vs. Closed Circulatory Systems • Animals with many cell layers need more than GV cavities. Diffusion is too much to ask. • Both open and closed systems have 3 parts: Blood or some equivalent, Blood Vessels, and a Heart. • Blood pressure is the motive force behind fluid movement.

7. Open Systems: Blood pumped into sinuses that bathe tissues Interstitial Fluid = The fluid surrounding the cells of tissues. In open circulation, there is no difference between interstitial fluid and blood. Heart is an elongated tube located dorsally Therefore it is called Hemolymph Insects and other arthropods

8. Closed Circulation:Blood always contained in vessels In closed circulation, interstitial fluid and blood are different and distinct One heart pumps blood into vessels that branch into smaller vessels Earthworms, squid, octopuses, vertebrates

9. Vertebrate adaptations of the CV system Evolutionary path of vertebrates: Fishes Amphibians Reptiles Mammals Systematic circulation  Pulmocutaneous and systematic  Double circulation Birds

12. Anatomy and pumping cycle of the mammalian heart

13. Pump Your Blood Songby Potsie and The Fonz • Pump, pump, pumps your blood. • The right atrium’s where the process begins, where the CO2 blood enters the heart. • Through the tricuspid valve, to the right ventricle, the pulmonary artery, and lungs. • Once inside the lungs, it dumps its carbon dioxide and picks up its oxygen supply. • Then it’s back to the heart through the pulmonary vein, through the atrium and left ventricle. • Pump, pump, pumps your Blood. • "PUMP YOUR BLOOD" SONG - VERSE TWO • Pump, pump, pumps your blood. • The aortic valve’s, where the blood leaves the heart, then it's channeled to the rest of the bod. • The arteries, arterioles, and capillaries too bring the oxygenated blood to the cells. • The tissues and the cells trade off waste and CO2, which is carried through the venules and the veins • Through the larger vena cava to the atrium and lungs, and we're back to where we started in the heart. • Pump, pump, pumps your blood 

14. Regulation of the cardiac Cycle Systole = contraction Diastole = relaxation Cardiac Output = Volume of blood pumped by left ventricle/min into systematic circuit. C.O. is a composite of heart rate and stroke Volume.

15. Maintaining the Heart’s rhythm

16. Structures of arteries, veins and capillaries

17. Blood Flow and Velocity • Law of continuity states if a pipes diameter changes over its length, a fluid will flow faster as the pipe narrows. • But the blood travels 1000x faster in the aorta than the capillaries. Why? • Because the narrowing component is based upon total cross sectional area. • That is, add up all of the capillaries cross sections and you will find that the “narrowing” effect is actually an expansion when you consider the number of capillaries. • Makes sense right? • Capillaries are very thin to promote gas exchange. Blood is designed to go through very slowly so this can occur

18. Blood Pressure Fluids flow from high hydrostatic pressure to low. Arteries or veins have the highest pressure? Why?

19. Summing it all up

20. Capillary exchange • Exchange of materials from in the capillaries to the interstitial fluid • Some movement occurs via endocytosis on one side of the wall of the capillary cell. • Diffusion of small molecules like O2 and CO2 • Sometimes the pressure is significant enough to force fluid from the inside the cap through the endothelial wall and to the intersitial fluid. We lose as much as 4L/ day. • Therefore you need a system to recollect this fluid.

21. The Lymphatic System • Diffusion of these “leaked’ fluids occurs into the lymph capillaries. • This fluid then drains into the circulatory system near the junction of the venae cava with the right atrium. • The lymph fluid gets filtered through lymph nodes which are conglomerations of white blood cells that screen out viruses and bacteria (get swollen upon infection)

23. Blood as a tissue

24. Stem cells in marrow allow for differentiation: An example of pluripotentcy

25. An Overview of Gas Exchange • Respiratory surfaces tend to be thin and have much surface area and be moist.

26. Water or land? Big or Small? Respiratory surfaces vary. • Sponges, Cnidarians, Flatworms ? • Respiratory surface is their plasma membrane. • Earthworms ? • Resp. surface is the skin, must be moist. • Spiders? Fish? Crickets?

27. Gills for aquatic animals vary. • Very folded to increase S.A. • Ventilation is very important

28. Fish Gills

29. Countercurrent Exchange of Blood and Oxygenated water is a way to maximize O2 diffusion.

30. Tracheal Systems are a series of hollow air tube inside a terrestrial animal

31. The Lungs: Restricted to one location, so the O2 and CO2 need to be delivered.

32. How breathing in lungs works

33. Loading and unloading of respiratory gases,

34. How does hemoglobin work to carry O2?

35. CO2 Transport in the blood