2. AP Biology Lab #10 Physiology of the Circulatory System

3. Blood pressure is a measurement of the force applied to the walls of the arteries as the heart pumps blood throughout the body. Blood pressure is determined by the strength of contraction, amount of blood pumped into the arteries, the viscosity of the blood, and the size and flexibility of the arteries.

5. fluids exert force against surfaces they come in contact with hydrostatic pressure

6. fluids flow from high pressure to areas of low pressure

7. fluids flow faster in narrower pipes… than wider pipes

8. BUT -even though capillaries are smaller than arteries; we have more capillaries

9. Therefore: greater cross- sectional area of capillaries

10. Therefore, fluids flow faster in arteries than capillaries

11. This is a good thing, b/c gas exchange can take place in the capillaries

13. Blood exerts a pressure against the wall of the vessel in which it is flowing.

15. At the arterial end of a capillary, blood pressure is greater than osmotic pressure, and fluid flows out of the capillary into the interstitial fluid. Capillary Red blood cell 15  m Tissue cell INTERSTITIAL FLUID Capillary Net fluid movement out Net fluid movement in Direction of blood flow Blood pressure Osmotic pressure Inward flow Outward flow Pressure Arterial end of capillary Venule end At the venule end of a capillary, blood pressure is less than osmotic pressure, and fluid flows from the interstitial fluid into the capillary. Figure 42.14

16. One type of cardiovascular disease, atherosclerosis –Is caused by the buildup of cholesterol within arteries Figure 42.18a, b (a) Normal artery (b) Partly clogged artery 50 µm250 µm Smooth muscle Connective tissue Endothelium Plaque

19. 90 or below is a normal diastolic reading 140 or below is a normal systolic reading

21. Cuff is wrapped around the upper arm & inflated until the pressure closes the brachial artery

22. *No blood can now flow past the cuff,

23. Pressure from cuff is higher than pressure in the artery

24. Stethoscope used to listen for the sound of blood flowing below the cuff

25. If artery is closed, no blood flowing… no sound.

26. Cuff is loosened until the blood can flow freely through the artery

27. You will hear the sound of blood pulsing into the artery

28. Pressure from blood is now greater than the pressure from the cuff

29. Cuff is loosened until the blood can flow freely through the artery

30. Sound below the cuff will disappear, pressure remaining in the artery when heart is relaxed.

32. Range depends on heredity, gender, environment

34. Figure 42.9 Artery Vein 100 µm ArteryVein Arteriole Venule Connective tissue Smooth muscle Endothelium Connective tissue Smooth muscle Endothelium Valve Endothelium Basement membrane Capillary All blood vessels – Are built of similar tissues – Have three similar layers Arteries have thicker walls – To accommod ate the high pressure of blood pumped from the heart

35. In the thinner-walled veins –Blood flows back to the heart mainly as a result of muscle action Figure 42.10 Direction of blood flow in vein (toward heart) Valve (open) Skeletal muscle Valve (closed)