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Cardiophysiology

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concise cardiophysiology that will help a medical student, reference from guyton and essential of medical physiology and others

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Cardiophysiology

  1. 1. VS
  2. 2. Dr: Ayub Abdulcadir Sheikh: • Postgraduate MBBS, at University of Somalia. • Resident physician at Sureya Medical Center. • A lecturer physiology at Frontier University. Dedication: To all my family especially may parents (Allah may bless you), also my student in frontier university.
  3. 3. TABLE OF CONTENTS 1. Introduction to Heart (anatomical, Histological)…………………………..…………. 1 2. Excitation contraction of Heart Muscle ………………………………………….…… 2 3. Cardiac cycle and pressures, volume changes ……………………………………...… 3 4. Cardiac cycle and pressures, volume changes ……………………………………...… 4 5. Regulation of Heart Pumping …………………………………………………...…..… 5 6. Cardiac Conductive system ………………………………………………………..….. 6 7. Autonomic nerve controlling Conductive system ………………………………….… 7 8. Electrocardiogram (ECG) …………………………………………………………. 8 - 9 9. Arrhythmias ……………………………………………………………………… 10 - 12 10. Cardiac Output ……………………………………………………………..………… 13 11. Overview circulation & control of blood flow ……………………….…………. 14 - 15 12. Microcirculation …………………………………………………………….………… 16 13. Control of blood flow ……………………………………………………….…… 17 – 23 14. Arterial blood pressure & it’s Regulation ………………………………………. 24, 25 15. Venous pulse & pressure …………………………………………………..…………. 26 16. Capillary pressure & it’s Regulation ………………………………………..………. 27
  4. 4. Page | 1 Cardiovascular system: 1. Blood. 2. Heart (cardiac). 3. Blood vessels. Heart Septum: 1. Interatrial septum. 2. Interventricular Septum Layers of heart: 1. Endocardium. 2. Myocardium. 3. Pericardium: a. Outer parietal pericardium :- Outer fibrous. Inner serous. b. Inner visceral (Epicardium) Chambers of heart: 1. Right Atrium. 2. Left Atrium. 3. Right Ventricle. 4. Left Ventricle. Cardiac Valves: 1. Atriovantriclular Valve: (Tricuspid and Mitral). 2. Semilunar Valve: (Pulmonary and Aortic) Cardiac Circulation: 1. Pulmonary. 2. Systemic. Blood Circulation: 1. Superior & Inferior Vena Cava. 2. Right atrium. 3. Right ventricle. 4. Pulmonary artery. 5. Lungs. 6. Pulmonary veins. 7. Left atrium. 8. Left ventricle. 9. Aorta. 10. Whole the body Actions of heart: 1. Chronotropic: heart rate. 2. Inotropic: contraction. 3. Dromotropic: velocity. 4. Bathmptropic: excitability. Types of cardiac muscles: 1. Atria. 2. Ventricle. 3. Conductive system Papillary muscle Histological cardiac muscle: • Intercalated disc. • Gap junction. • Myofibril (Actin & Myosin filaments) Cardiac has 2 pumps: a) Right or left blood pump. b) Upper or lower blood pump. About heart: ➢ Size of your fist. ➢ 250 g (female) ➢ 300 g (male). ➢ Superior surface of diaphragm ➢ Left of the midline ➢ Anterior to the vertebral column, posterior to the sternum
  5. 5. Page | 2 Cardiac Action Potential: 1. Fast Sodium Channel. 2. Slow Calcium Channel (Na Ca Channel) Phases of Action Potential in Cardiac muscle: 1. Phase 0 = Depolarization (Na influx). 2. Phase 1 = Initial repolarization (K outflux). 3. Phase 2 = Plateau (Ca influx). 4. Phase 3 = Rapid repolarization (K outflux). 5. Phase 4 = Resting membrane potential (Na-K ATPase) Excitation – Contraction of cardiac muscle: 1. Arrival of action potential on T-Tube. 2. Activation of Ca channel. 3. Ca from extracellular enters the cell. 4. Binding Ca to Ryanodine receptors of Sarcoplasmic reticulum. 5. Release of sarcolasmic calcium. 6. Accumulation of Calcium in the cell. 7. Formation of Ca signals. 8. Ca binds to TnC. 9. Opening of actin myosin binding site. 10. ATP activates Myosin head. 11. Formation of Cross-bridge b/w actin and Myosin. 12. Cardiac muscle contraction occurs (pumping of blood). 13. Again ATP binds to myosin head. 14. Detachment of Actin and Myocin. 15. Ca released from TnC. 16. Relaxation will occur. 17. Closure of Actin binding sites. 18. Some Ca is pumped in the ECF whereas the others pumped in the Sarcoplasmic reticulum. Velocity of signal conduction in cardiac muscle: 1. Atria = 0.3 m/s. 2. Ventricle = 0.5 m/s. 3. Purkinje fiber = 4 m/s Refractory period of cardiac muscle: Relative refractory period. The strength of contraction of cardiac muscle depends to a great extent on the concentration of calcium ions in the extracellular fluids. Calcium Induced Calcium Release (CICR): Look at Step 4 and 5
  6. 6. Page | 3 Cardiac Cycle: 1. Systole. 2. Diastole. Normal range of cardiac cycle = 0.8 s During exercise: systole, more diastole. Systole: 1. Atrial systole. 2. Ventricular systole: a) Isometric contraction. b) Ejection period. Diastole: 1. Atrial diastole. 2. Ventricular diastole: a) Protodiastole. b) Isometric relaxation. c) Rapid filling. d) Slow filling. e) Last rapid filling. Cardiac sounds: 1. First sound: Closure of Atrioventricular valve. 2. Second sound: Closure of seminular valve. 3. Third sound: Rushing of blood into ventricles. 4. Fourth sound: Contraction of atrial musculature. End Systolic Volume: 60 – 80 ml. End Diastolic Volume: 130 – 150 ml. Stroke volume: (EDV - ESV) (130 - 60) Normal = 70 ml Ejection Fraction: (SV / EDV) X 100. Normal = > 50% Events of the cardiac cycle for left ventricular function, showing changes in left atrial pressure, left ventricular pressure, aortic pressure, ventricular volume, the electrocardiogram, and the phonocardiogram.
  7. 7. Page | 4 The volume-pressure diagram: Phase I: Period of filling. Phase II: Period of isovolumic contraction. Phase III: Period of ejection. Phase IV: Period of isovolumic relaxation. Fig: Changes in intraventricular volume and pressure during a single cardiac cycle (red line). The shaded area represents the net external work (EW) output by the left ventricle during the cardiac cycle. Shift to right: (if increased time of filling). Ex: increased volume of blood Shift to left: (if decreased time of filling). Ex: increased sympathetic activity. P wave: Atrial depolarization (Atrial contraction). QRS complex: Ventricular Depolarization (Ventricular Contraction). T wave: Ventricular Repolarization (Ventricular Relaxation). Atrial relaxation is mixed in QRS complex but does not appear in ECG. Preload: Is the pressure during filling of the ventricle. End Diastolic pressure Ventricular filling Afterload: Is the arterial pressure against which the ventricle must contract. End Systolic pressure Ventricular ejection
  8. 8. Page | 5 Regulation of Heart Pumping: 1. Frank Starling Mechanism (Venous Return). 2. Autonomic Nervous System (Sympathetic & Parasympathetic) 3. Other factors. 1. Frank Starling Mechanism (intrinsic control) states that: A. If increased venous return leads. B. greater the heart muscle is stretched during filling & C. the greater is the force of contraction & D. the greater the quantity of blood pumped into the aorta. 2. Distribution and function of Autonomic Nervous System: A) Sympathetic A N S: Location: In SA node, AV node, Septum, Whole the heart. Function: • Increases heart rate = 70 -220 bpm. • Increases force of contraction. • Increases volume of blood pumping. • Increases ejection pressure. • Increases cardiac output = 5 – 30L/minute. B) Parasympathetic A N S: Location: In SA node, AV node. Function: • Strongly decreases heart rate = <50 bpm. • Slightly decreases force of contraction. • Slightly decreases volume of blood pumping. • Slightly decreases ejection pressure. • Normal or slight decrease cardiac output = 5L/minute. Increasing the arterial pressure load (up to a limit) does not decrease the cardiac output 3. Other factors: • Hyperkalemia: (cardiac weakness, abnormal rhythmus, or block conduction). • Hypocalcemia: (decreased excitability and contractility). • Hypercalcemia: (spastic contraction). Due to less development of sarcoplasmic reticulum of cardiac muscle, the contraction of heart muscle is depending among the concentration of Extracellular calcium. • Slightly increase in temperature: (increases the permeability of ions also increases the contractility of heart).
  9. 9. Page | 6 Conductive system: 1. Sino Atrial Node (Pacemaker): Three Internodal fibers: A. Anterior (Bachman) Internoadal F. B. Middle (Wenckebach) Internoadal F. C. Posterior (Thorel) Internoadal F. 2. Atrioventricular Node. 3. Atrioventricular Bundle (Bundle of Hiss): A. Right Bundle Branch. B. Left Bundle Branch. 4. Purkinje Fiber. Importance of Conductive System: 1) Generation of self rhythmical excitation of heart. 2) Conduction or propagation of these rhythmical excitation. Average human age of 100 year the heart will beat approximately 3 billion times. Velocity of Conduction: 1. SA node = 70 – 80 bpm. 2. AV node = 40 – 60 bpm. 3. Purkinje fiber = 20 – 40 bpm Total velocity conduction before ventricular contraction is 0.16 s. ➢ Slow conduction in the transitional, nodal, penetrating AV bundle is due to diminished number of Gap junction. ➢ Rapid conduction in Purkinje fiber is due to presence of large number of Gap junction. Properties of conductive system: 1. Self excitation continually due to: ➢ Opening and Influx of Na & Ca ions in the node. 2. Hyperpolarization continually due to: ➢ Opening and Outflux of K ions in the node.
  10. 10. Page | 7 ➢ Parasympathetic nerve fiber: 1. Release of Acetylcholine (Ach). 2. Ach binds with Muscarinic Cholinergic receptors. 3. Activation of G protein. 4. Activation &opening of K channel, then K outflux. 5. G protein also Inactivates Adenyl Cyclase. 6. Decreased production of cAMP. 7. Closure of Na and Ca channels leads. 8. HYPERPOLARIZATION. “Cardiac cycle” = more than 0.8 s ➢ Sympathetic nerve fiber: 1. Release of Epi/Nor-epinephrine 2. These binds with Adrenergic receptors. 3. Activation of G protein. 4. Activates Adenyl Cyclase. 5. Increased production of cAMP. 6. Opening & influx of Na and Ca channels & 7. Inactivation & closing of K channel leads . 8. DEPOLARIZATION. “Cardiac cycle” =less than 0.8 s Ventricular Escape: when severe stimulation of parasympathetic fiber causes the heart to stop, then after 5 – 20 s the heart will beat again. ECTOPIC PACEMAKER: is a pacemaker that is not in the original position (sinus node).
  11. 11. Page | 8 Electrocardiography (ECG): is the interpretation of the electrical activity of the heart over a period of time. Advantages of ECG: 1. Heart rate. 2. Heart rhythm. 3. Abnormal electrical conduction. 4. Poor blood flow to heart muscle (ischemia) 5. Heart Attack. 6. Coronary artery disease. 7. Hypertrophy of heart chambers. ECG Paper: A. Light line of Small square = 1 X 1 mm. B. Dark line of Large square = 5 X 5 mm. C. X axis of one small square = 0.04 s. D. Y axis of one small square = 0.1 mV 12 ECG lead: 1. Bipolar Limb leads: • Limb lead I: Between the right arm (negative electrode) and the left arm (positive electrode). • Limb lead II: Between the right arm (negative electrode) and the left leg (positive electrode). • Limb lead III: Between the left arm (negative electrode) and the left leg (positive electrode). 2. Unipolar limb lead (augmented leads): • aVR: Between the right arm (positive electrode) and left arm + left leg (negative electrode). • aVL: Between the left arm (positive electrode) and right arm + left leg (negative electrode) • aVF: Between the left foot (positive electrode) and right arm + left arm (negative electrode). 3. Unipolar Chest lead (precardial leads): • V 1 : Over 4th intercostal space near right sternal margin • V 2 : Over 4th intercostal space near left sternal margin • V 3 : In between V2 and V4 • V 4 : Over left 5th intercostal space on the mid clavicular line • V 5 : Over left 5th intercostal space on the anterior axillary line. • V 6 : Over left 5th intercostal space on the mid axillary line. Einthoven triangle: The Heart is said to be in the center of an imaginary equilateral triangle drawn by connecting the roots of three limbs (Rt Arm, Lt Arm, Lt Leg).
  12. 12. Page | 9 Normal ECG: • Normal ECG consists of waves, complexes, intervals and segments. • Waves of ECG recorded by limb lead II are considered as the typical waves. • Isoelectric line: above (Positive wave) and below (Negative wave) Abnormal ECG: 1. Abnormal pattern of cardiac excitation resulting in different types of arrhythmias. 2. Abnormalities of myocardium. 3. Cardiac abnormalities due to alteration in plasma electrolytes. 4. Cardiac involvement secondary to other diseases.
  13. 13. Page | 10 Arrhythmia: irregular heartbeat or disturbance in the rhythm of heart Causes of Arrhythmia: 1. Scarring of heart tissue from a prior heart attack 2. High blood pressure 3. Hyperthyroidism 4. Smoking 5. Alcohol, drug abuse 6. Stress, diabetes. Sign & Symptoms of Arrhythmia: 1. Palpitation, Chest pain, Shortness of breath, 2. Lightheadedness or dizziness, 3. Sweating, 4. Fainting (syncope) or near fainting. Complication: 1. Stroke. 2. Heart Failure.
  14. 14. Page | 11 Sinus tachycardia Sinus Arrhythmias Sinus Bradycardia
  15. 15. Page | 12 paroxysmal ventricular tachycardia
  16. 16. Page | 13 Cardiac output: “The quantity of blood pumped into the aorta each minute. by the heart”. Normal CO: in males (5.6L/min), in females (4.9L/min). • Cardiac index: “is the minute volume expressed in relation to square meter of body surface area”. • Cardiac index = CO/ body surface area. • Normal Range: 2.6–4.2 L/min/m2 • Below 2.2 L/min/m2 indicate cardiogenic shock. Body Surface Area = Height (cm) X Weight (Kg) 3600 • Cardiac Reserve: “difference b/w the rate at which the heart pumps blood and its maximum capacity for pumping blood at any given time”. • Cardiac Reserve = Maximum CO – Normal CO X 100 / Normal CO. • It’s expresses as percentage %. • Example Normal person = 400% (if Max CO = 25L/min & Norm CO = 5l /min) Distribution of CO in the body When total peripheral resistance is more than 100, both the cardiac output and the Arterial pressure are decreased, vice verse. Factors that cause Hypereffective heart (age, sex, exercise, pregnancy, nervous stimulation, physiological ventricular hypertrophy, environment, emotional). Factors that cause Hypoeffective heart (severe increased arterial pressure, inhibition of nervous stimulation, congenital and heart disease, fever).
  17. 17. Page | 14 Blood flow through tissues is determined by interaction of these: 1. Tissue needs. 2. Cardiac output. 3. Arterial blood pressure. Function of circulation: 1. Transport: nutrients, O2, waste products, hormones, drugs. 2. Maintain appropriate internal environment.
  18. 18. Page | 15 Blood flow through a blood vessel is determined by two factors: (1) Pressure difference. (2) Vascular resistance. Ohm’s law: “the blood flow is directly proportional to the pressure difference but inversely proportional to the resistance”. Two type of Blood flow through a blood vessel: 1. Streamline (linear) flow. 2. Turbulent flow. Vascular resistance of two types: 1. Total peripheral vascular resistance: 1 PRU (peripheral resistance unit) 2. Total pulmonary vascular resistance: 0.14 PRU. A valuable characteristic of the vascular system is that “all blood vessels are distensible”. The most distensible by far of all the vessels are the veins. • Steps in measuring Blood Pressure:
  19. 19. Page | 16 ❖ Structure of Capillary: a) Unicellular layer of endothelial cells. b) Surrounded by a thin basement membrane. c) Two pores or pathways: • Intercellular cleft: water & water soluble ions • Caveolae: Transport of plasma protiens Function of the microcirculation: is transport of nutrients to the tissues and removal of cell excreta. The metarterioles and the precapillary sphincters are in close contact with the tissues that serve as open and close for controlling tissue blood flow ❖ Types of Capillary: 1. Continuous. 2. Fenestrated. 3. Sinusoid. When the molecular weight of the substance is less, the permeability of that substance is more. ❖ Interstitium: • Is the space between cells of the total volume of the body • The structure of the interstitium: 1. Collagen fiber bundles. 2. Proteoglycan filaments. 3. Small rivulets of “free” fluid and small free fluid vesicles. ❖ Starling forces: • The four primary forces that determine whether fluid will move through capillary & interstitium: 1. Capillary pressure (Pc). 2. Interstitial fluid pressure (Pif) 3. Capillary plasma colloid osmotic pressure (Πp) 4. Interstitial fluid colloid osmotic pressure (Πif)
  20. 20. Page | 17 Types of Control tissue blood flow by: 4. Local control. 5. Endothelial Derived Factors. 6. Nutrient and Ions control. 7. Humoral control. 8. Nervous control. Factors determine the Control tissue blood flow: 1. Increase or decrease in Heart Rate. 2. Vasoconstriction or Vasodilatation. 1. Local Control of blood Flow: B) Acute local control: rapid changes in local vasodilatation or vasoconstriction. A) Long Term control: slow, controlled changes in flow over a period of days, weeks, or even months. Properties: 1. Increases in Tissue Metabolism Increase Tissue Blood Flow. 2. Reduced Oxygen Availability Increases Tissue Blood Flow. 3. Two theories that increase tissue blood flow: a) Vasodilator Theory (increased rate metabolism and decreased O2 & nutrient availability = formation of vasodilator substance). b) Oxygen Demand Theory (decrease O2 concentration leads vasodilatation). Example of Acute local control: 1. “Reactive Hyperemia” Occurs after the Tissue Blood Supply Is Blocked for a Short Time. 2. “Active Hyperemia” Occurs When Tissue Metabolic Rate Increases. Properties: 1. Increase or decrease in the physical sizes. 2. Increase or decrease in numbers of blood vessels supplying the tissues. Example of Long Term control: 1. “Tissue Vascularity” occurs if the metabolism in a tissue is increased for a prolonged period, vascularity increases (angiogenesis). 2. “Role of Oxygen in Long-Term Regulation” occurs at high altitudes, premature babies, 3. Development of Collateral Circulation . 4. 2. Endothelial Derived Factors: A) Nitric Oxide: (Vasodilatation). B) Endothelin: (Vasoconstriction).
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  22. 22. Page | 19 3. Nutrient & Ions for Local Control of blood Flow: A) Vasodilatation: 1. Decreased glucose. 2. Vitamin B deficiency. 3. Acetate and Citrates. 4. Increased K. 5. Increased Mg. 6. Increased H. 7. Increased CO2. B) Vasoconstriction: 1. Increased Ca+2 . 4. Humoral & Hormonal Control of blood Flow: A) Vasodilators: 1. Bradykinins. 2. Histamine. 3. Acetylcholine. 4. Thrombins. 5. Bacterial toxin. 6. Shear stress. 7. Substance P. 8. ATP. 9. Prostaglandin E, PGI2. 10. Atrial Natriuretic Peptide B) Vasoconstrictor: 1. Norepinephrine. 2. Angiotensin II. 3. Antidiuretic hormone (ADH). 4. Thromboxane. 5. Prostaglandin F. 6. Trauma.
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  24. 24. Page | 21 (+/-) (+/-) (+/-) • 5. Nervous Control of blood Flow: A) Cardioaccelator Center: • Pressor area • Give sympathetic activity: 1. Increase heart rate. 2. Increase heart contractility. 3. Release of epi-norepinephrine from adrenal medulla. B) Vasomotor center: • Pressor area • Give sympathetic activity: 1. Maintainance of normal vascular tone (Arteries & Veins). 2. Vasoconstrictor both “Artery and Vein” C) Cardioinhibitory center: • Depressor area from “sensory area” • Give Parasympathetic activity: 1. Decrease heart rate. 2. Decrease heart contractility. Sensory Areas from: • Nucleus Tractus Solitarus, Nucleus Ambigious and Dorsal Motor Nucleus Activity depends on the blood pressure: 1. Activates or inhibit the Cardioaceletor & Vasomotor center. 2. Activates or inhibit the Cardioinhibitory center. • Carotid sinus: (Glossopharyngeal) • Aortic Arch: (Vagus)
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  26. 26. Page | 23 Autoregulation: the mechanism in which returning normal blood flow to optimal level. 1. Metabolic theory: When the arterial pressure becomes too great, the excess flow provides too much oxygen and too many other nutrients to the tissues and “washes out” the vasodilators released by the tissues. 2. Myogenic theory: When high arterial pressure stretches the vessel, this in turn causes reactive vascular constriction that reduces blood flow nearly back to normal. N.B: “A rapid increase in arterial pressure causes an immediate rise in blood flow. Then blood flow in most tissues returns almost to the normal level, even though the arterial pressure is kept elevated”. Autoregulation Organs Are: Heart, Kidney, Brain.
  27. 27. Page | 24 Calculatiob of Mean arterial pressure (MAP): 1. Diastolic pressure + 1/3 of pulse pressure. 2. MAP = Systolic Pressure + 2(Diastolic Pressure) 3 Arterial blood pressure: is pressure exerted by the column of blood on wall of arteries. • It is expressed in four different terms: 1. Systolic blood pressure - 120 mm Hg (110 mm Hg to 140 mm Hg. 2. Diastolic blood pressure - 80 mm Hg (60 mm Hg to 80 mm Hg. 3. Pulse pressure - 40 mm Hg (SP 120 – DP 80 = 40). 4. Mean arterial blood pressure: the average pressure existing in the arteries - 93.3 mmHg. • Two factors influence the variation of arterial blood pressure: 1. Physiological variation: age, sex, body build, after meal, during sleep, etc. 2. Pathological variation: hypertension, hypotension. Systolic pressure is quickly and easily variable in contrast to diastolic pressure. 4 regulatory mechanisms to maintain the blood pressure within normal limits: 1) Nervous mechanism or short - term regulatory mechanism. 2) Renal mechanism or long - term regulatory mechanism. 3) Hormonal mechanism. 4) Local mechanism.
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  29. 29. Page | 26 Venous pressure is the pressure exerted by the contained blood in the veins. • Two factors influence the variation of venous pressure: 1. Physiological variation: Changing from standing to supine position, Forced expiration, Contraction of abdominal and limb muscles, etc. 2. Pathological variation: a) Increases in: Low cardiac output, venous obstruction, Paralysis of muscles, renal failure, etc. b) Decreases in: Severe hemorrhage, Surgical shock • Types of venous pressure: 1. Central venous pressure: is the pressure in the vena cava and right atrium. 2. Peripheral venous pressure: is the pressure in peripheral veins. • FACTORS REGULATING VENOUS PRESSURE: 1. Contraction of the left ventricles and its pressure leads forward of blood to the veins then to the right atrium. 2. Set points of right atrial pressure of 0mmHg maintain the venous pressure. 3. Resistance offered by venous wall. 4. Volume of blood flowing through veins. 5. Peripheral resistance is inversely to venous pressure. • Relation of respiration and venous pressure: 1. Valsalva maneuver: is the forced expiratory effort with closed glottis. a) intrathoracic pressure becomes positive (+50mmHg). b) Decrease in central venous pressure. c) 30 seconds endurance test. d) It is used to correct the abnormal heart rhythms 2. Müeller maneuver: is the forced inspiratory effort with closed glottis. a) intrathoracic pressure decreases (-70mmHg). b) Increase in central venous pressure. c) Is used to evaluate Upper respiratory tract problems & Sleep apnea syndrome. The Veins Function as Blood Reservoirs in these locations: a) Spleen b) Liver, c) Large abdominal veins, d) Venous plexus of skin. • Venous pulse is observed only in larger veins near the heart such as jugular vein. • Venous pulse recording is used to determine the rate of atrial contraction. • Recording of jugular venous pulse is called phlebogram. • Kussmaul sign: increase in venous distention + increase in venous pressure
  30. 30. Page | 27 • Also called capillary hydrostatic pressure. • Is responsible for the exchange of various substances between blood and interstitial fluid through capillary wall. • Normal value of different type capillary pressure: a) Arterial end of the capillary = 30 - 32mmHg. b) Venous end of capillary = 15mmHg. c) Glomerular capillary pressure = 60mmHg. d) Pulmonary capillary pressure = 7mmHg. • Arterioles play an important role in regulating the capillary pressure. ➢ Capillary membrane is permeable to all substances except plasma proteins (albumin). ➢ Normal oncotic pressure is about 25 mm Hg. ➢ Oncotic pressure plays an important role in filtration across capillary membrane, particularly in renal glomerular capillaries. 1. Coronary Circulation. 2. Cerebral Circulation. 3. Splanchnic Circulation. 4. Skeletal Muscle Circulation. 5. Cutaneous Circulation.

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