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7/30/2019 Arterial & Venous System Final
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ARTERIAL & VENOUSSYSTEM
Dr. MRS. Chhaya Saraf
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LEARNING ISSUES
Understand the importance of arterialdistension and recoil
Describe the mechanisms of peripheral
arterial pulsationsArterial system & functions
Venous system & functions
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Anatomy
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WALLS OFBLOODVESSELS
Circular Smooth Muscle
Vaso-constriction/dilation
Elastin and collagen
Strengthens, Anchors
EndotheliumMinimize friction
Sympathetic stimulation(alpha receptors) Noradrenalinecauses vasoconstrictionSympathetic inhibition VasodilatationVasomotor tone-Even at rest sympathetic tone is there
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WINDKESSELEFFECT
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VASCULAR DISTENSIBILITY
P
Dilatation
Increased Blood flow
Distensibility allows blood vessels to accommodatepulsatile output & also smooth flow to tissues
Veins are 6-10 times more distensible
Fractional increase in volume per 1 mmHgpressure rise
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VASCULAR COMPLIANCE/CAPACITANCE
Total quantity of blood stored per 1 mmHgpressure rise
Compliance = Distensibility x volume
In veins compliance is 24 times more thanarteries (8x3)
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VOLUME PRESSURE CURVE
Increased sympathetic tone
increases pressure
Helpsin shifting blood e.g.hemorrhage
Small pressure changeafter large volume change
More pressure changeafter small volume change
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DELAYED COMPLIANCE-STRESS RELAXATION
Transfusion
Hemorrhage
Increased volume initially increases the pressure but
later on it comes to normal due to stretch
Stress relaxation of muscle
Readjustmentof muscle
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VENOUS SYSTEM
Main features Compliant Compressible
Extremity veins have
Valves Mean peripheral venous
pressure4-6 mmHg
Central Venous
Pressure(RAP)~ 0-4 mmHg Cardiac pumping VR
Increased RAP openscollapsed veins
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PERIPHERAL VENOUS PRESSURE
Venoconstriction by sympathetic stimulationmaintains the circulation & shifts a blood
Specific reservoirs Spleen
Liver
Large abdominal veins
Venous plexus beneath the skin
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Role of gravity
For every 13.6 mm distancethere is 1 mm Hg pressureincrease
It is seen in veins as well asarteries so arterial pressure inlegs is 100+90=190mmHg
HYDROSTATIC PRESSURE
AND VENOUS PRESSURE
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SKELETAL MUSCLE PUMP VENOUS PUMP
Incompetence & destruction of valves - varicose veins
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NORMAL ARTERIAL PRESSUREPULSATIONSATAORTICROOT
Pressure pulsations reduces tozero in capillaries d/to
distensibility & resistance inarteries
Dicrotic notch& wave
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DETERMINANTSOF PULSE PRESSURE
PULSEPRESSURE = STROKEVOLUMECOMPLIANCE(DISTENSIBILITY)
Systolic pressure
Diastolic pressure
Pulse pressure
In old age due to non
compliant arteries PP isincreased
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ABNORMAL PRESSURE PULSE WAVE
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Damping duringpropagation
PRESSUREPULSE PROPAGATION
pulse wave is not seenin capillaries.
Last curves show decreasein intensity due to changein Resistance &
Compliance of peripheralvessels
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MAIN STUDY MATERIALGUYTON 15THCHAPTER
Thank You