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Physiology - Cardiovascular Notes.docx

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Department
Nursing
Course Code
NUR1 324
Professor
Prof

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Flow Pressure ResistanceFlowvolume mL or L time minCardiac output5 Lmino Flow generated by left or right heart 3 Flow through a vesselarea cm xmean velocity sec o Velocity not the same at all points in cross sectionCrosssectional area of aortafew cm o Velocity in aortahigh pressurefluid moving quickly o Average speed in big vessel like aorta 30cmsec o Down arterial treecrosssectional area increasing and velocity decreasingflow same o Flow slowest in smallest vesselsPractical units cm HO or mmHg 2 Pressure Paforcearea mmHgpghheight cm HO 2o Blood pressure 12080 mmHg o Central venous pressure 6cm HO 2o pghdensity cant change x gravity cant change x height can changepressure exerted by column 10cm high is 10cmo 1mmHg136 mm HO136 cm HO 22o Atmospheric pressure0 o Not all pressure hydrostaticpressure decreases as fluid moves out of a bag and down tubeMeasuring CVP central venous pressure o Veins which come into the right atrium have approximately the same pressure as in the right atriumCVPpressure in RA o Keep manometer at higher level than right atriumcause fluid to move out of manometer and into RA through catheter until hydrostatic pressureRA pressure CVP o When the liquid in the manometer is at the same level as the RA the PinPout and the flow0Measure the amount of liquid in the manometer at that time and that will be your CVP o CVP510 cm H0 2 Jugular vein distension o Put is chest cavityeverything pushed to leftRA squeezed and pressure increases insidetransmural pressure increases pressure insidepressure outsideCVP increasesjugular vd o Treatmenttube through ribs to take fluid outPerfusion pressurearterial pressure o Perfusion pressure drives flow through vessels o Perfusion pressurearterial pressurevenous pressureo Venous pressure negligible so perfusion pressurearterial pressure o Perfusion pressurepressure flowing inpressure flowing outPinPoutP0flow0 no perfusion pressureno flowFlowperfusion pressureresistance o Absolute pressure not importantdifference in pressures is important o Increase in ppincrease in flowVSincrease in resistancedecrease in flow o ResistancePRUmmHgml x secLaminar or parabolic flow o Velocity drops from centre of vessel to edge of vessel velocity at edge of vessel0 Parabolic flowexplains viscosity as blood flow fromo Normal flow through vesselslaminar flow smooth flowPoiseuilles Law 4o R8 vLr o R proportional to length and viscosity o R inversely proportional to radius Small changes in rlarge changes in Rsmaller rlarger Rless flowResistance o Resistance in series RRR RR or R 1212 FlowP RR 12 Dont want system in series because dont want all organs getting same amount of flow ex exercisemore flow to muscles at that time o Resistance in parallel 1R1R1R RR or R 1212 FlowPRPR 12 Want system in parallel so small arterial pressure to drive flow through vessels Concentrate on controlling size of vessels which will control R of each organ and that controls flow through each organAnatomyFlow of blood o RARVpulmonary trunkR and L pulmonary arteries 2lungs2 R pulmonary veins and 2 L pulmonary veinsLALVaortarest of bodysuperiorinferior vena cavaRAAtria chambers through which blood flows from veins to ventriclesits contraction aids ventricular filling but is NOT essential for itVentriclesdrives blood to pulmonary system to get oxygenated and then blood to rest of body Arterieslowresistance tubes conducting blood to the various organs with little loss in pressurealso act as pressure reservoir for maintaining blood flow during ventricular relaxationArteriolesmajor site of resistance to flowsmooth muscles relax and contract which controls individual organs resistance by controlling crosssectional areaindividual organs control flow of blood to themselvesVeins o Lowresistanceblood flow back to heart o Superior vena cavablood from top part of body o Inferior vena cavablood from bottom part of bodyPulmonary vessels o 4 pulmonary veins 2 from R lung and 2 from L lung o 2 pulmonary arteries 1 to R lung and 1 to L lungboth from pulmonary trunkSeptums o Interatrial septumseparates RA and LA o Interventricular septumseparates RV and LV o LV free wall thicker than RV free wallLV pumps to whole body Pericardiumsac around heartfat and connective tissueValves o AV valvesblood flow between atriums and ventriclesTricuspid valve 3 flapsRARVBicuspid valve mitral valve2 flapLALV o Semilunar valvesblood flow between ventricles and aorta and pulmonary arteriesPulmonic valveRV2 pulmonic arteriesAortic valveLVaorta o Valves sit in fibrous ring which is not made of cardiac tissueo Chordae tendinae connective tissuedont stretch attached to valves and papillary musclesVentricles develop increased pressure causes valve to closeventricles contractpapillary muscles contractpull on chordate tendinaepull on leaflets on valves so they dont ever into atriumMake sure no regurgitation from ventricles to atriumsRegurgitation if chordae tendinae or papillary muscles weak or not workingvalve replacementCovering of heart o Endocardiumcovering of ventricles and atriums o Myocardiummuscle outside ventricles and atriums o Epicardium sticks to musclePericardial fluidPericardium outsidevery tough o Pericardial fluid acts as lubricant so heart can move easily when it contractsIf it fills with too much fluid ventricles compressed and cant fill properlycant pump properlyless blood flowdecreased BP
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