1. Cardiovascular Physiology （心血管生理学）
Qiang XIA (夏强), PhD
Department of Physiology
Room C518, Block C, Research Building, School of Medicine
Tel:

2. Vascular Physiology（血管生理学）

3. Lecture Outline Functional parts of blood vessels Hemodynamics
Arterial blood pressure
Microcirculation
Venous pressure and venous return
The lymphatic system

4. Functional parts of blood vessels
Elastic vessels (Windkessel vessels)
（弹性血管）
Resistance vessels (Precapillary resistance vessels)（阻力血管）
Exchange vessels（交换血管）
Capacitance vessels（容量血管）
Distribution vessels（分布血管）
Shunt vessels（短路血管）

6. Hemodynamics（血流动力学）
Blood flow
Q= DP/R = (P1-P2)/R

7. Q= PA/R Q: cardiac output, 5 L/min R: total peripheral resistance
PA: aortic pressure
Q= PA/R

8. Resistance of blood flow
Poiseuille Law: Q=pDPr4/8hL
h: viscosity
r: radius of the vessel
L: length of the vessel
R= 8hL/pr4
Q= DP/R
Jean Louis Marie Poiseuille \pwä-'zəi\ (April 22, December 26, 1869) was a French physician and physiologist.
Poiseuille was born in Paris, France.
From 1815 to 1816 he studied at the École Polytechnique in Paris. He was trained in physics and mathematics. In 1828 he earned his D.Sc. degree with a dissertation entitled Recherches sur la force du coeur aortique. He was interested in the flow of human blood in narrow tubes.

9. r: main determinant of blood flow

10. Arterial blood pressure（动脉血压）
Arteries

11. Blood pressure measurement 1. Direct (invasive) measurement technique

12. 2. Indirect (non-invasive) measurement technique

13. Pulse pressure (PP，脉压): the difference between SP and DP
Systolic pressure (SP，收缩压): the maximum arterial pressure reached during peak ventricular ejection
Diastolic pressure (DP，舒张压): the minimum arterial pressure just before ventricular ejection begins
Pulse pressure (PP，脉压): the difference between SP and DP
Mean arterial pressure (MAP，平均动脉压): the average pressure in the cardiac cycle (=DP+1/3PP)
These figures should not be stacked vertically– this confuses the scale on the abscissae.

14. Mean arterial pressure (MAP)

15. To estimate systolic and diastolic pressures, pressure is
released from an inflatable cuff on the upper arm while
listening as blood flow returns to the lower arm.

16. Click here to play the
Sphygmomanometry
Flash Animation

17. Blood Pressure Classification Chart
Classification of blood pressure for adults age 18 years and older
Blood Pressure Classification Chart
Category
Systolic (mm Hg)
Diastolic (mm Hg)
Normal
Lower than 120
Lower than 80
Prehypertension
Hypertension  
Stage 1
90-99
Stage 2
160 or higher
100 or higher
Adapted from The Seventh Report on the joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), NIH Publication No , May 2003
The classification chart is based on adults, aged 18 and older, who are not taking high blood pressure medicines and who are not acutely ill. If systolic and diastolic measurements fall into different categories, the higher category should be used to classify the person's blood pressure status.

18. Factors affecting arterial blood pressure
Stroke volume
Heart rate
Peripheral resistance
Elastic vessels
Blood volume
Ventricular ejection

19. MAP = CO  SVR Q= PA/R Q: cardiac output (CO)
R: total peripheral resistance (SVR)
PA: aortic pressure (MAP)
MAP = CO  SVR

20. 1 2 3 5 4

21. The blood moved in a
single heart contraction
stretches out the arteries,
so that their recoil
continues to push
on the blood, keeping it
moving during diastole.
Movement of blood into and out of the arteries during the cardiac cycle

23. Arterial pulse（动脉脉搏）

24. In response to the pulsatile contraction of the heart:
pulses of pressure move throughout the vasculature, decreasing in amplitude with distance

25. Arterial pulse recorded in different vessels

26. Arterial pulse recorded under different conditions

27. Microcirculation（微循环）
Function:
Transfer of substances between blood & the tissues

28. Structure of microcirculation
A-V shunt

29. 3 pathways Circuitous channel (Nutritional channel)（营养通路） 2 1 3 4 5
A-V shunt 1 2 3 4 5

30. Thoroughfare channel（直捷通路）
A-V shunt 1 2 3 4 5

31. Arteriovenous shunt (A-V shunt)（动-静脉短路）1 2 3 4 5

32. Blood travels from artery to arteriole to capillary to venule to vein

33. Arterioles（微动脉） Two major roles:
To be responsible for determining the relative blood flow in individual organs at any given MAP
To be a major factor in determining MAP

34. Dynamic adjustments in the blood distribution to the
organs is accomplished by relaxation and contraction
of circular smooth muscle in the arterioles.
Graphic in proofs looked as if arterioles are EMPTY.

35. Arteriolar Radius & Blood Flow
Click here to play the
Arteriolar Radius & Blood Flow
Flash Animation

36. Arteriolar Resistance & BP
Click here to play the
Arteriolar Resistance & BP
Flash Animation

37. Local Control of Blood Flow
The mechanism independent of nerves or hormones by which organs and tissues alter their own arteriolar resistances, thereby self-regulating their blood flows
Active hyperemia（主动充血）
Flow autoregulation（血流自身调节）
Reactive hyperemia（反应性充血）
Local response to injury（对损伤的局部反应）

38. Local control of organ blood flow
Active hyperemia and flow autoregulation differ in their
cause but both result in the production of the same
local signals that provoke vasodilation.

39. Reactive hyperemia – When an organ or tissue has had its blood supply completely occluded, a profound transient increase in its blood flow occurs as soon as the occlusion is released

40. Response to injury – Tissue injury causes a variety of substances to be released locally from cells or generated from plasma precursors. These substances make arteriolar smooth muscle relax and cause vasodilation in an injured area

41. Extrinsic Control Sympathetic nerves（交感神经）
Parasympathetic nerves（副交感神经）
Noncholinergic, nonradrenergic autonomic neurons (NO or other noncholinergic vasodilator substances)（NANC）
Hormones (epinephrine, angiotensin II, vasopressin, atrial natriuretic peptide)

42. Sympathetic stimulation of alpha-adrenergic receptors cause
vasoconstriction to decrease blood flow to that location.
Sympathetic stimulation of beta-adrenergic receptors lead to
vasodilation to cause an increase in blood flow to that location.

43. Renin-angiotensin system（肾素-血管紧张素系统）

44. ANGII can be produced directly by conversion of angiotensinogen by the tissue plasminogen activator (tPA), cathepsin G and tonin or by hydrolysis of angiotensin I by chymase and cathepsin G.
CAGE = chymostatin-sensitive angiotensin
II-generating enzyme

45. Robert Toto & Biff F. Palmer. Am J Nephrol 2008;28:372–380

46. Vasopressin（血管升压素）

47. Endothelium-derived vasoactive substances
Vasodilator factors
PGI2 – prostacyclin（前列环素）
EDRF (endothelium-derived relaxing factor, nitric oxide)
EDHF (endothelium-dependent hyperpolarizing factor)

48. The 1998 Nobel Prize in Physiology or Medicine
Nitric oxide as a signaling molecule in the cardiovascular system
Louis J Ignarro Ferid Murad Robert F Furchgott

50. Sildenafil, the prototypical PDE5 inhibitor
A phosphodiesterase type 5 inhibitor, often shortened to PDE5 inhibitor, is a drug used to block the degradative action of phosphodiesterase type 5 on cyclic GMP in the smooth muscle cells lining the blood vessels supplying the corpus cavernosum of the penis. These drugs are used in the treatment of erectile dysfunction, and were the first effective oral treatment available for the condition. Because PDE5 is also present in the arterial wall smooth muscle within the lungs, PDE5 inhibitors have also been explored for the treatment of pulmonary hypertension, a disease in which blood vessels in the lungs become abnormally narrow.

51. Vasoconstrictor factors – Endothelin-1（内皮素-1）

52. Major factors affecting arteriolar radius
Diversity among signals that influence contraction/relaxation
in vascular circular smooth muscle implies a diversity of
receptors and transduction mechanisms.

55. Capillaries（毛细血管） Main function:
Exchange of nutrients and metabolic end products

56. Capillaries lack smooth muscle, but contraction/relaxation of circular smooth muscle in upstream metarterioles and precapillary sphincters determine the volume of blood each capillary receives.

57. the primary point exchange between the blood and the
Capillary walls
are a single
endothelial cell
in thickness.
The capillary is
the primary point exchange between the blood and the
interstitial fluid (ISF).
Intercellular clefts assist the exchange.
Graphic is confusing since ALL of lumen is red (but plasma is clear)– accompanying photo shows an RBC.

58. Structure of capillary wall

59. Structure of the capillary wall
Continuous: found in muscle, skin, lung, central nervous system
Fenestrated: found in exocrine glands, renal glomeruli, intestinal mucosa
Discontinuous: found in liver, spleen, bone marrow

60. Relationship between total cross-sectional area and flow velocity
Six balls in per minute
mandates six balls out per minute.
Therefore, the velocity of the balls in the smaller tubes is slower.

61. There are many, many capillaries, each with slow-moving
blood in it, resulting in adequate time and surface area
for exchange between the capillary blood and the ISF.

62. Diffusion
Pinocytosis
Filtration and Reabsorption

63. Filtration Absorption
Movement of fluid and solutes out of the blood is called filtration.
Movement of fluid and solutes into the blood is called absorption.
Absorption

64. Net filtration pressure (or Effective filtration pressure)

65. EFP Pc
EFP + Filtration
EFP -  Reabsorption

66. Fluid Change Across Capillary Wall
Click here to play the
Fluid Change Across Capillary Wall
Flash Animation

67. Dynamic changes in vasodilation/vasoconstriction in the
Effects of arteriolar vasodilation or vasoconstriction on capillary blood pressure
Dynamic changes in vasodilation/vasoconstriction in the
arterioles regulate downstream pressures and flow rates.

68. Venous pressure and venous return
（静脉血压与静脉回流）

69. Venous pressure
Peripheral venous pressure（外周静脉压）──
the pressure in the peripheral veins
Central venous pressure (CVP，中心静脉压)──
the pressure in the thoracic vena cava & the right atrium 4~12cmH2O

70. Central venous pressure measurements were obtained for three astronauts (indicated by different colors). Notice the dramatic CVP changes that occurred during launch as well as when the astronauts arrived in space.

71. Measurement of central venous pressure
Jugular venous pressure is a clinical measure of central venous pressure. It is the height of the pulsating column of blood in the great veins draining into the right atrium and, in malaria, is a useful measure of over- or under-hydration (hyper- or hypovolaemia).
Jugular venous pressure is the vertical distance, measured in cm, between the venous pulsation in the neck and the sternal angle (junction of the second rib with the sternum) when the patient is propped up on pillows at 45 to the horizontal. In this position, the sternal angle marks the level of the right atrium. The height of the jugular venous pressure is normally 4–5 cm. In order to measure it, the patient should be made as comfortable and relaxed as possible. It is difficult or impossible to identify venous pulsation if the neck muscles are contracted. Try to achieve good (oblique) lighting of the neck. Look for the jugular venous pulse in the internal jugular vein or its external jugular tributaries on both sides of the neck with the patient's chin tilted up and slightly away from you. The following characteristics help to distinguish jugular venous pulsation from carotid arterial pulsation. The jugular venous pulse:
has two waves for every single carotid artery pulsation; make this comparison by gently palpating the carotid pulse on the opposite side of the neck;
falls with inspiration and rises with expiration (except where there is cardiac tamponade);
can be obliterated by pressing firmly but gently with the back of the index finger placed horizontally just above the clavicle at the root of the neck;
may be visible only when the patient is lying flat (in cases of hypovolaemia) or when the patient is sitting upright at 90 (for example, in severe congestive cardiac failure);
is usually impalpable.

72. At rest, approx. 60% of the total blood volume is in the veins
At rest, approx. 60% of the total blood volume is in the veins. Sympathetically mediated venoconstriction can substantially increase venous return to the heart.

73. Determinants of venous pressure
Contraction of venous smooth muscle
Sympathetic neurons
Hormonal and paracrine vasodilators and vasoconstrictors
Skeletal muscle pump
Respiratory pump

74. Venous valve

75. Varicose vein（曲张静脉）

77. Varicose vein
great saphenous vein

78. Venous flow is assisted by the skeletal muscle pump
mechanism working in combination with one-way valves.

79. Respiratory activity (Respiratory pump)

80. Alterations in “venous return” alter end-diastolic volume (EDV);
increased EDV directly increases stroke volume and cardiac output.

81. The Lymphatic System （淋巴系统）
The lymphatic system is a network of small organs (lymph nodes) and tubes (lymphatic vessels) through which lymph flows

82. Lymphatic fluid, formed by the slight mismatch between filtration and absorption in the capillaries, returns to the blood in the veins.

83. Terminal lymphatics

84. Lymphatic pump

85. Relation between interstitial fluid pressure and lymph flow

86. Significance of lymphatic return
Absorption of proteins
Transportation of fat and other nutrients
Balance between plasma and interstitial fluid
Protection

87. Elephantiasis
（象皮肿）
Chronic, often extreme enlargement and hardening of cutaneous and subcutaneous tissue, especially of the legs and external genitals, resulting from lymphatic obstruction and usually caused by infestation of the lymph glands and vessels with a filarial worm.

88. Elephantiasis
Also known as lymphatic filariasis, this condition occurs when parasitic worms (any of several types of filaria worms) infest the lymphatic system.  The filaria are transmitted by mosquitoes to the blood and can build a population in the lymph nodes, blocking fluid drainage from arms, legs, genitals, or breasts.  It is called elephantiasis (literally, "elephant condition") because in extreme cases, the arms and legs look like the limbs of an elephant. Elephantiasis affects over a 100 million people around the world.  However, most cases are not as extreme as in this photo!

90. A summary of dynamic changes in MAP and TPR.
Check figure #s in “from …” boxes
A summary of dynamic changes in MAP and TPR.

91. Blood loss causes a reduction in MAP, which, if left unchecked, would result in rapid and irreversible damage to the brain and the heart.

92. The End.