1. Circulation

2. Arteries AWAY Branch Typically oxygenated.

3. Capillaries Smallest. Most abundant. – How many?? – Why? Exchange

4. Veins TOWARDS Converge. Typically deoxygenated.

5. 3 Layers of the Vascular Wall Tunica interna Tunica media Tunica externa.

6. Tunica Interna/Intima Lining. Endothelium. Supported by loose CT. Only layer in capillaries.

7. Tunica Media Primarily smooth muscle plus elastic fibers. Most prominent layer in arteries.

8. Tunica Media Smooth muscle tone Regulated by: – Metabolites – Hormones – Sympathetic vasomotor neurons.

9. Vasomotor neurons constantly release NE onto TM smooth muscle. – What does the NE do? – Why have a constant release?

10. Increased NE release by a vasomotor neuron causes: – Tunica media smooth muscle tone to: – Vessel diameter to: – Resistance to blood flow in the vessel to: – Blood flow thru the vessel to:

11. This gentleman has fatty plaques in his lower leg arteries. How do you think they affect blood flow? How does that relate to his facial expression? His doctor recommends that the sympathetic nerves to those arteries be cut. Why?

12. Tunica Externa/Adventitia Primarily collagen Function? Most prominent layer in veins

13. Elastic Arteries Aorta and major branches. Act as AUXILIARY PUMPS.

15. Regional distribution Significant layer Muscular Arteries

16. Smallest. May or may not have an externa. Highly innervated by vasomotor neurons. Arterioles

17. Regulation of blood pressure and flow. Easy to change the diameter. – How would you do it? – Why would you want to? Arterioles

18. Capillaries Smallest. Thin walls Billions Function? Almost everywhere.

19. Continuous capillaries –––––––– Most common and least permeable. No endothelial “holes” Intercellular clefts. Abundant in…

20. Fenestrated capillaries – Endothelial “holes” – Intercellular clefts – Found in…

21. Sinusoidal capillaries. –––––––– Most permeable and least common. Big endothelial “holes” Intercellular clefts. Can have macrophages in their lining. Why? – Found in…

22. Why are capillaries organized into beds? What tissues will have high densities of capillary beds?

23. What determines whether the sphincters are open or closed? What do precapillary sphincters do? Vascular shunt vs. True capillaries

24. If you were running, 1. Precapillary sphincters in your biceps femoris would … 2. Precapillary sphincters in your large intestine would…

25. Veins All 3 tunics. TE is the largest. Thin walls Large lumens. Low resistance High compliance

26. Veins Smooth muscle tone prevents too much distention. Capacitance vessels/Blood reservoirs. 65%

27. Veins Low pressure vessels. Contain valves. – What do they do? – Where are they needed?

28. Venous Sinuses Thin-walled veins made of endothelium only.

29. Blood Flow Volume per time. Flow thru systemic circuit = cardiac output. Flow to individual organs varies. – How is this achieved?

30. Blood Pressure Force per unit area exerted on the vessel wall by blood. Millimeters of mercury (mmHg). All vessels

31. Resistance Opposition to flow Measure of friction. Peripheral resistance. Direction!

32. While this guy is running, - the resistance of the arterioles of his quadriceps needs to… - the resistance of arterioles in his colon needs to…

33. Sources of Resistance Blood viscosity. Total vessel length. Vessel radius.

34. Viscosity resistance. Can you drink one of these with a straw? What makes it challenging?

35. What are the major contributors to blood viscosity? Does viscosity change often in a healthy person? An increase in plasma EPO will cause resistance to…

36. Total Vessel Length Length resistance. Does total vessel length change in a normal person?

37. A B Which tube has greater intrinsic resistance? As total vessel length increases, resistance will… As total vessel length decreases, blood flow will…

38. Vessel Radius (1/radius 4 ) resistance

39. Does vessel radius change in a normal healthy person? Which vessels? How is the change achieved?

40. Which tube has the greater intrinsic resistance? What layer of the vessel wall has the greatest effect on vessel resistance? a. b. c. Interna Media Externa A B

41. Resistance  (length)(viscosity) (radius) 4

42. Which tube has the LEAST resistance? Which tube has the GREATEST resistance?

43. FLOW  PRESSURE GRADIENT RESISTANCE

44. As resistance decreases, flow will… As the pressure gradient increases, flow will… Which does the heart influence more: pressure gradient or resistance?

45. Blood Pressure Why do all blood vessels have a BP? Which vessel do we usually care about? Where is systemic BP the highest? Where is systemic BP the lowest?

46. Arterial Blood Pressure Model

47. What would happen to AP if the amount of blood pumped into the arteries increased? Thus, arterial pressure varies directly with…

48. What would happen to AP if the resistance in the arterioles went up? Thus, arterial pressure varies directly with…

49. What would happen to AP if there was more blood in the entire system? Thus, arterial pressure varies directly with…

50. Systolic Blood Pressure

51. Diastolic Blood Pressure

53. What creates it? How/Where do you measure it? What’s its relationship to heart rate? Pulse

54. Pulse Pressure Change in arterial pressure caused by ventricular systole. Varies directly with… PP = SBP – DBP.

55. Mean Arterial Pressure (MAP) Arterial BP fluctuates. Why? MAP is the pressure driving blood flow. MAP is a weighted average of SBP and DBP.

56. MAP = ⅔DBP + ⅓SBP MAP = DBP + ⅓PP Mean Arterial Pressure (MAP)

57. Capillary Blood Pressure Low BP. Why is this good? (Think about the structure of a capillary.)

58. Venous Blood Pressure Even lower BP. Very small gradient.

59. What is responsible for venous return? Remaining force imparted by ventricular systole. Gravity. Skeletal muscle pump. Respiratory pump. Venomotor action.

62. Skeletal Muscle Pump

63. Respiratory Pump Deep Inspiration Thoracic volume will… Pressure in thoracic cavity will… Pressure in thoracic veins will… Blood flow into thoracic veins and towards the heart will…

64. Venomotor Tone An increase in sympathetic activity causes: – NE release on the TM of medium/large veins to… – Venous pressure to… – Venous return to…

65. Controlling MAP Why do we need to control it? Short term Long term

66. Vasomotor Cardioinhibitory Cardioacceleratory Brain Centers for Short Term MAP Control

67. Increased vasomotor center activity __creased sympathetic output to arterioles Vaso__________ __creased peripheral resistance __creased blood pressure What about a decrease in vasomotor activity?

68. Increased cardioacceleratory center activity __creased sympathetic output to heart __creased heart rate and stroke volume __creased cardiac output __creased blood pressure What about a decrease in cardioacceleratory activity?

69. Increased cardioinhibitory center activity __creased parasympathetic output to heart __creased heart rate __creased cardiac output __creased blood pressure What about a decrease in cardioacceleratory activity?

70. Baroreceptor Reflex

71. Baroreceptors signals the cardiac and vasomotor centers via CN IX and X. Frequency of these impulses is proportional to MAP. Cardiac and vasomotor centers adjust their output accordingly.

72. Demonstrating the Baroreceptor Reflex Take the subject’s radial pulse. Find the carotid pulse point and GENTLY press on it. What will happen to the radial pulse? Why?

73. Adrenal Medullary Mechanism Release epinephrine (and a small amt of NE) in response to: – Large drops in MAP. – Increases in physical activity. – Stressful situations.

74. –––––––––– HR SV CO PR BP Adrenal Medullary Mechanism How would activation of the adrenal medulla affect:

75. Renin-Angiotensin-Aldosterone System Renin Angiotensin II

76. VasoconstrictionAldosterone &Thirst Antidiuretic hormone Increased TPR Increased BV Increased BP Renin-Angiotensin-Aldosterone System Angiotensin II

77. In response to a fall in MAP, renin release by the kidney would: In response to a rise in MAP, renin release by the kidney would: Renin-Angiotensin-Aldosterone System

78. A 25yo woman complains to her doctor of headaches and blurred vision. Her blood pressure is 200/130 mmHg. After the BP has been reduced, investigations are made to find the cause of the problem. It’s discovered that her left renal artery is narrowed. Why would this cause the rise in BP?

79. Long Term BP Control Achieved by the... Primarily done by altering...

80. ____________ blood volume _________BP Long Term BP Control Large increase in BP ____________ urine formation ____________ urine output

81. As we go from the aorta to the billions of capillaries, what happens to the total cross- sectional area? What happens to the velocity of blood flow?

82. As we go from the billions of capillaries to the venae cavae, what happens to the total cross- sectional area? What happens to the velocity of blood flow?

83. The Paradoxical Problem of the Vasomotor Center

84. Local Regulation of Blood Flow Autoregulation - adjustment of blood flow to each tissue according to its immediate needs. Surplus or deficiency of local chemicals influences local vessel diameter and blood flow.

85. Working Muscle Tissue Tissue CO 2 levels ___ Tissue O 2 levels ___ Arterioles serving tissue vaso________ Lactic acid levels ___ ______blood flow to tissue CO 2 _______ Lactic acid _______ Heat _______ O 2 ________ Local Regulation of Blood Flow Tissue temp. ____

86. Capillary Exchange Btwn blood plasma and tissue fluid. Nutrients, wastes, signaling molecules FLUID

87. Capillary Fluid Exchange 4 forces – Capillary osmotic pressure. – Capillary hydrostatic pressure. – Interstitial osmotic pressure. – Interstitial hydrostatic pressure.

88. Capillary Hydrostatic Pressure A.k.a… What does it do? ISF CAPILLARY HP

89. Capillary Osmotic Pressure Mostly due to… What does it do? ISF CAPILLARY OP

90. Interstitial Hydrostatic Pressure Usually inconsequential b/c… What would it do? ISF HP CAPILLARY

91. Interstitial Osmotic Pressure Usually inconsequential b/c… What would it do? ISF OP CAPILLARY

92. Capillary Fluid Exchange Thebalance of what 2 forces typically determines if fluid enters or exits the capillary? Net filtration pressure

93. Capillary Filtration If capillary HP >> capillary OP, – What kind of fluid movement will occur? ISF CAPILLARY

94. Capillary Reabsorption If capillary HP << capillary OP, – What kind of fluid movement will occur? ISF CAPILLARY

95. Pressure Capillary Fluid Exchange Is capillary HP constant?? Is capillary OP constant?? Distance along the capillary Arterial endVenous end

96. Pressure Capillary Fluid Exchange At which end of the capillary is filtration likely to occur? At which end is reabsorption likely to occur? Distance along the capillary Arterial endVenous end

97. CAPILLARY EXCHANGE Water and other substances leave capillaries because of net outward pressure at the capillary's arteriolar ends What is hydrostatic pressure? It is _____ mm of Hg. Which is greater than the inward _________ force of ____ mm of Hg. The net outward pressure of _____mmHg causes substance to flow into the __________ space and into the ______. Water enters a capillary's venule end because of a net inward pressure of ___ mm. Which force is greater at the venule end? This force is _____ mm of Hg. Why does the outward force of 41.3 mm Hg decrease to 21.3 mm Hg? Now substances leave the _________ space and go into the _________. What maintains the osmotic pressure in the capillaries? substances move in and out along the length of the capillaries according to their respective concentration gradients. arteriole venule 41.3 osmotic2813.3 interstitialcells Capillary's arteriolar endsCapillary's venular end osmotic 28 interstitialcapillary ’ s venule end lymphatic Hydrostatic pressure changes due to inefficient heart Blood backs up into vascular system causing edema Pulmonary edema - Which ventricle is failing? Systemic edema - Which ventricle is failing? Ascites - abdominal edema. 6.7

98. Capillary Fluid Exchange Capillary HP usually slightly exceeds capillary OP. Why does this matter?