基礎(chǔ)醫(yī)學(xué)各論：10.循環(huán)系統(tǒng)生理3

1、Cardiovascular Physiology （心血管生理學(xué)） Vascular Physiology（血管生理學(xué)）（血管生理學(xué)） ? Lecture Outline Functional parts of blood vessels Hemodynamics Arterial blood pressure Microcirculation Venous pressure and venous return The lymphatic system Functional parts of blood vessels nElastic vessels (Windkessel vessels

2、) n（彈性血管） nResistance vessels (Precapillary resistance vessels)（阻力血管） nExchange vessels（交換血管） nCapacitance vessels（容量血管） nDistribution vessels（分布血管） nShunt vessels（短路血管） Hemodynamics（血流動力學(xué)） Blood flow Q= DP/R = (P1-P2)/R Q= PA/R Q: cardiac output, 5 L/min R: total peripheral resistance PA: aortic pr

3、essure Poiseuille Law: Q=pDPr4/8hL h: viscosity r: radius of the vessel L: length of the vessel Q= DP/R Resistance of blood flow R= 8hL/pr4 Jean Louis Marie Poiseuille pw-zi (April 22, 1799 - December 26, 1869) was a French physician and physiologist. Poiseuille was born in Paris, France. From 1815

4、to 1816 he studied at the cole 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. r: main determinant of blood flow

5、 If the radius of an arteriole is halved, its resistance will fall to _ of its original value. A 1/2 B 1/4 C 1/8 D 1/16 E 1/32 Decreasing the radius of a vessel by one-half its original radius will have what effect upon blood flow to distal portion? A Blood flow will decrease to 50% of original flow

6、. B Blood flow will decrease by 25% of original flow. C Blood flow will decrease to 10% of original flow. D Blood flow will decrease to 6% of original flow. Arteries Arterial blood pressure（動脈血壓） Blood pressure measurement 1. Direct (invasive) measurement technique 2. Indirect (non-invasive) measure

7、ment technique Systolic pressure (SP，收縮壓，收縮壓): the maximum arterial pressure reached during peak ventricular ejection Diastolic pressure (DP，舒張壓，舒張壓): the minimum arterial pressure just before ventricular ejection begins Pulse pressure (PP，脈壓，脈壓): the difference between SP and DP Mean arterial press

8、ure (MAP， 平均動脈壓平均動脈壓): the average pressure in the cardiac cycle (=DP+1/3PP) Mean arterial pressure (MAP) 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. Click here to play the Sphygmo

9、manometry Flash Animation Blood Pressure Classification Chart CategorySystolic (mm Hg)Diastolic (mm Hg) NormalLower than 120Lower than 80 Prehypertension120 - 13980 - 89 Hypertension Stage 1140-15990-99 Stage 2160 or higher100 or higher Adapted from The Seventh Report on the joint National Committee

10、 on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), NIH Publication No. 03-5233, 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 measureme

11、nts fall into different categories, the higher category should be used to classify the persons blood pressure status. Classification of blood pressure for adults age 18 years and older Factors affecting arterial blood pressure Stroke volume Heart rate Peripheral resistance Elastic vessels Blood volu

12、me Ventricular ejection Q= PA/R Q: cardiac output (CO) R: total peripheral resistance (SVR) PA: aortic pressure (MAP) MAP = CO SVR 1 2 3 5 4 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 diastol

13、e. Movement of blood into and out of the arteries during the cardiac cycle Arterial pulse（動脈脈搏） In response to the pulsatile contraction of the heart: pulses of pressure move throughout the vasculature, decreasing in amplitude with distance Arterial pulse recorded in different vessels Arterial pulse

14、 recorded under different conditions Clinical Application of Arterial Pulse ? Systematic examination of pulses: Which and what order?Where and how?Why? 1. Radial arteryRadial side of wrist. With tips of index and middle fingers. To assess rate and rhythm. Simultaneously with femoral to detect delay.

15、 Not good for pulse character. 2. Brachial arteryMedial border of humerus at elbow medial to biceps tendon. Either with thumb of examiners right hand or index and middle of left hand. To assess pulse character. To confirm rhythm. 3. Carotid arteryPress examiners left thumb against patients larynx. P

16、ress back to feel carotid artery against precervical muscles. Alternatively from behind, curling fingers around side of neck. Best for pulse character and, to some extent, left ventricular function. To detectcarotid stenosis. At resuscitation (CPR). 4. Femoral arteryPatient lying flat and undressed.

17、 Place finger directly above pubic ramus and midway between pubic tubercle and anterior superior iliac spine. To assess cardiac output. To detect radiofemoral delay. To assessperipheral vascular disease. 5. Popliteal arteryDeep within the popliteal fossa. Compress against posterior of distal femur w

18、ith knee slightly flexed. Mainly to assess peripheral vascular disease. In diabetics. 6. Dorsalis pedis (DP) and tibialis posterior (TP) arteries (foot) Lateral to extensor hallucis longus (DP). Posterior to medial malleolus (TP). As above. 7. The abdominal aortaWith the flat of the hand per abdomen

19、, as body habitus allows. In peripheral vascular disease. To detect aneurysmal swelling. From: http:/www.patient.co.uk/ Microcirculation（微循環(huán)） Function: Transfer of substances between blood 28:372380 Vasopressin（血管升壓素） Vasodilator factors PGI2 prostacyclin（前列環(huán)素）（前列環(huán)素） EDRF (endothelium-derived relaxi

20、ng factor, nitric oxide) EDHF (endothelium-dependent hyperpolarizing factor) Endothelium-derived vasoactive substances 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 Sildenafil, the proto

21、typical 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 u

22、sed 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 w

23、hich blood vessels in the lungs become abnormally narrow. Vasoconstrictor factors Endothelin-1（內(nèi)皮素（內(nèi)皮素-1） Diversity among signals that influence contraction/relaxation in vascular circular smooth muscle implies a diversity of receptors and transduction mechanisms. Major factors affecting arteriolar

24、radius From the biologically active substances produced from arachidonic acid which are listed below, select which is a vasodilator and platelet aggregation inhibitor produced by endothelial and smooth muscle cells A Thromboxane A2 B Lipoxin A C Lipoxin B D Leukotriene C4 E Leukotriene D4 F Leukotri

25、ene B4 G Leukotriene F4 H Leukotriene E4 I Thromboxane B2 J Prostacyclin (PGI2) From the biologically active substances produced from arachidonic acid that are listed below, select which one is synthesized by platelets and promotes vasoconstriction. A Thromboxane A2 B Lipoxin A C Lipoxin B D Leukotr

26、iene C4 E Leukotriene D4 F Leukotriene B4 G Leukotriene F4 H Leukotriene E4 I Thromboxane B2 J Prostacyclin (PGI2) Capillaries（毛細血管） Main function: Exchange of nutrients and metabolic end products Capillaries lack smooth muscle, but contraction/relaxation of circular smooth muscle in upstream metart

27、erioles and precapillary sphincters determine the volume of blood each capillary receives. The capillary is the primary point exchange between the blood and the interstitial fluid (ISF). Intercellular clefts assist the exchange. Capillary walls are a single endothelial cell in thickness. Structure o

28、f 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 Structure of the capillary wall Six balls in per minute mandates six balls out per minute. The

29、refore, the velocity of the balls in the smaller tubes is slower. Relationship between total cross-sectional area and flow velocity 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. D

30、iffusion Pinocytosis Filtration and Reabsorption Movement of fluid and solutes into the blood is called absorption. Absorption Filtration Movement of fluid and solutes out of the blood is called filtration. Net filtration pressure (or Effective filtration pressure) EFP + Filtration EFP - Reabsorptio

31、n EFP Pc Click here to play the Fluid Change Across Capillary Wall Flash Animation Dynamic changes in vasodilation/vasoconstriction in the arterioles regulate downstream pressures and flow rates. Effects of arteriolar vasodilation or vasoconstriction on capillary blood pressure In which of the follo

32、wing lists of blood vessels is the sequence of vessels arranged from highest to lowest total cross-sectional area in the body? A Arteries, arterioles, capillaries, veins B Arterioles, capillaries, arteries, veins C Capillaries, arterioles, veins, arteries D Veins, capillaries, arterioles, arteries E

33、 Arteries, veins, arterioles, capillaries Venous pressure and venous return （靜脈血壓與靜脈回流） Venous pressure Peripheral venous pressure（外周靜脈壓） the pressure in the peripheral veins Central venous pressure (CVP，中心靜脈壓) the pressure in the thoracic vena cava make this comparison by gently palpating the carot

34、id 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 visibl

35、e 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. At rest, approx. 60% of the total blood volume is in the veins. Sympathetically mediated venoconstriction can subs

36、tantially increase venous return to the heart. Determinants of venous pressure Contraction of venous smooth muscle Sympathetic neurons Hormonal and paracrine vasodilators and vasoconstrictors Skeletal muscle pump Respiratory pump Venous valve Varicose vein（曲張靜脈） Varicose vein great saphenous vein Ve

37、nous flow is assisted by the skeletal muscle pump mechanism working in combination with one-way valves. Respiratory activity (Respiratory pump) Alterations in “venous return” alter end-diastolic volume (EDV); increased EDV directly increases stroke volume and cardiac output. The lymphatic system is

38、a network of small organs (lymph nodes) and tubes (lymphatic vessels) through which lymph flows The Lymphatic System （淋巴系統(tǒng)） Lymphatic fluid, formed by the slight mismatch between filtration and absorption in the capillaries, returns to the blood in the veins. Terminal lymphatics Lymphatic pump Relat

39、ion between interstitial fluid pressure and lymph flow Absorption of proteins Transportation of fat and other nutrients Balance between plasma and interstitial fluid Protection Significance of lymphatic return Elephantiasis （象皮腫） Chronic, often extreme enlargement and hardening of cutaneous and subc

40、utaneous 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. 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 flu