3.2 Myocardium & Blood flows Flashcards

Question

Cerebral blood flow what is it

Answer 1

750mls min 50mls 100g min 15% CO

Answer 2

Cerebral metolbic rate o2 consumption 3-3.5mls o2 100g min 50mls in total brain weight 1.4kg - use 20% basal o2 conspump hgih level metbolic activty - not tolerate momentray o2

Answer 3

No -global flow ulatered change distrib - motor cortex increase flow small - other receive less

Answer 4

CPP / CVR MAP-CPP ``` Factors affecting CVR Metabolic autoreg pressure autoreg chemical factors nervous system ```

Answer 5

autoreg - ability tissue adjust blood supply - recive flow carry fxn local vasodil metbolite impratnat min min reg control cbf exampls admin indction tho- decrease cbf - decreae cmro2 cbf decrease fitting causes incrase work - cbf increase supply meets demand metbolic regulation - moment moment reg cbf glocal may reman constant draw curtve metabolic ontrol cbf - page 63 flow metabolism coupling

Answer 6

rel constant cbf - despite map 50-150 page 63 Myogenic theory Pressure arteriole increase - increase stethc vessel vascular sm responds -> stretch contract - resting tone higher results decrease redius - increased resistance vells - return blood flow to normal despite continuation pressure quickly - seconds

Answer 7

Chronic htn & acute sympathetic stim Main point - lower limit shift to right not tolerate drop bp - without decrease cbf Low BP not tolerated espec i fealvated ICP Neonates - pressure reg left shift platue anrrow 30-90 slopes upward to right lower bp - phys approp left shift decrease upper limit neonate less toerate higher bp

Answer 8

page 64 Curve almost liner 2.6-10.6 CBF linear change over pco2 wide rang Where is the normal Pco2 Decrease CB F - sustain hypocanpoa - dimish time - bic equil across bbb brain ISF pH - normal thus so does CBF Effect - advance 4-hours Sudnden return normal art pco2 - excess CBF & Rise OCp

Answer 9

Cerbal vasoldtion in response hypoxia low flow limits amount ocygen deliver - vasodilation causes prevent further decrease cbf- with decrease art pco2 Proven in hypernaric chamaber Sifficenmt o2 dissovled - oxygne receive adeq o2 despite low cbf - acute hypocapnic vasoconsitrciton counter ewffect hypox vosdil remoced further decrease cbf

Answer 10

Page 65 CBF not affected until po2 <50mmhg 6.6kpa Shape odc for hb po2 falls o2 content not alter much upper part as falls <60 oxy content falls rapidly - steep odc not much decrease o2 supply in level reach cerbrel arterioles - vasodialte cbf incrases to maint o2 delivery

Answer 11

SNS - not import chang cerebral circ - change CVR autonomic stimulation allter cvr small amount Improtant in CBF - effects on CPP Barorecporor monitor mean carotid arterial pressure BP falls - neuroanl firing cartoid sinus diecrase reflex - rapid powerful sympathet stim - hr contract vasocn attemp maintain map

Answer 12

Stretch receptors walls heart blood vessel Carotid sinus aortic arch Arterial Ra LA Pulm veins small dilation ICA - increase rate firing distention - decrease sympathehtic increase vagal response Carotid aortic baro - end NTS at medulla - releaseglutamte, siognal go caudal ventrolaterral medulla Carotid sinus reflex & pressure autoreg - aim mantain constant cbf - despite change map Carotid sinus reflex - responds rapider - improtant moment moment activ - chjange positon pressure autoreg - minutes Under cond extreme hypoxia - ishaemic response - chusin reflex Max sympathetitic stim - last ditch resore CBF & o2 2supply

Answer 13

CPP CVR CPP - driving flow blood perfusion organs - diff map & venous draing tissue added consideration brain - icp icp higher cenous pres then map - icp type something occurs lungs heart - starling resistor CPP i MAP minus greatr CVP or ICP dterm - CPP require all three measure

Answer 14

Curve drawn map x and cbf y - reason MAP est CPP larger than ICP & JVP Easy measure Meausre ICP - more incasive Path condition ICP high - high map low

Answer 15

Decrease ICP | Mimise blood loss

Answer 16

Brain ecnlsoed righid bony skull total volume conents fixed attempt increase volume any conents - rapid icnrease pressure Diagr pg 67 Presuure not rise much initally csf out ventricle into extracran SA space vuffer exhausted - rise very abrupt Intracrain coent normally - 85% brain 10% csf blood 5%

Answer 17

Head up tilt No obstruction drainage avoid vdilator cerebral Hyperventilation Mannitol Contolled hypotension

Answer 18

Decrease CPP - hydrostitc effect keep jug veinbs collapse - no congestion Min venous bleeing Addit - decre VR - pool blood extermity - hypotension activated carotid sinus - icrease bp fianl efect perfusion - effectie pressure & metab autoreg Idisag - increase risk venous air ebolism drop cpp & cbf may not be warranted

Answer 19

Rapidly reduce art pco2 Decrease 4% every mmHg decrease art pco2 from normal intracerbral pressure decrease - desired effect Advant - rapid reliable potent easily control disadv not lasting -less 4-12h -> decrease bic brain ECF - restores ecf pH to normal & vascon - decreased allow art pco2 rise - tend excess increase cbf

Answer 20

Hypertonic - not cross cell membrane draws water all cells doesnt direct affect CBF - does decrease intrcerbal decrease volumes - rapid IV volume expanded water ICF - osmotic diruesis - loss fluid & decreae IV fluid benefical - not direct depend on diuresis

Answer 21

Urea less able cross bbb hpyeronic urea - cause cerebral dehydr - reduce icp rapid excrete kidney

Answer 22

RAP low & Vp in vein above RA falls - hdyrostic pressure effect - pressure drops almost 0 & veins collaprse jug vein in erect position normally collapse

Answer 23

Pressure grad - favours entry air cerbral dural sinus - despire fact jug vein distended Dural sinus not collapse rigid walls -presure can subatmopher - air can sucked in - during caniotomy in sitting venous air embolism - large & rapid

Answer 24

200- 250 mls/min 5% CO Supply LV - predom diastole - subendo flow to LV cease to LV during systole (commonest site MI) Lower pressure in RV - differences less Draw flow curves related to cardiac cycle 69

Answer 25

Driving pressure for coronoary circulation Aortic diastolic pressure - larger of LVEDP or RAP (cor sinus pressure) LV diastolic pressure & rap smaller than aortic - CPP is stating aortic diastolic Intraop - peripheral arterial disatolic pressur - index co pp Difficult acurate diastolic pressure peripher - niv & Invasive

Answer 26

Starling resistors Three pressures i heart Arterial pressure IV pressure Cor sinus / RAP CPP - perfusion pressure during diastole - highest most flow - lv occurs Exa,[;s LVV - systole Aort - intracetric pressure =120-120= 0 LV duastole Aorti diastolic - RAP 80-5=75 RV during systole = Aortic - intraventricular 120-25=95 RV during systole Aortic - RAp 80-5 =-5 LV larger flow - larger mass - effects improtant Subendo vsesles - subject ffull impact iv pressure - ceases during systole maj artery epicardial surface

Answer 27

Cor sinus drain in RA 90% Thebesian vessels pO2 cor sinus blood 20mmHg - myocardium high extracion ratio 55-65%

Answer 28

55-65 Blood supply low relative to oxygen conumsption myodacridum extract a lot of oxygen for unit blood flow Signif - heart requires more oxy cor blood flow must increase Extraction high - no reason extraction increase Increased myocardial consumption must be acomp by increase flow

Answer 29

Cor artery flow increases to supply oxygen to match demand Normally high extraction increased - provide more oxygen High extraction ratio remains high - rest exercise anaemia Heart cant devleop oxygen debty cor flow can increase 5 times 1250 Increase metabolic autreg in arterioles counteract symp med vasocon - increase mostly during ddiastole Hypox hypercarb increase h ion, lactate, k adenosine

Answer 30

During strenous exercise - energy skeltal muscle exceed supply atp - aerobic metbolism - o2 deilvery insufficient energy atp anaerobic metab Lactate prod After exercise increased - increased o2 ptake Metabolise excsess lactate & replace atp stoore Size o2 determ measure excess o2 consumpt end exercise until basal levels Myocardial cannot accum o2 debt - all aerobic

Answer 31

Total hepatic flow 1500mls/min 30% Hepatic artery 300-500ml min press 90-100 Portal vein 1000-1200mls min - 10mmhg Some autoreg in artery portal - not autoreg Recirpocal relationship - increased sympathetic active - increase portal flow - decrease heptaic artery liver reseovr - 500mls - deliver cirulation - vasocon

Answer 32

40-50 hep art 50-60 portal vein Liver - cannot supply artery supply removed

Answer 33

50mls o2 mn 20% o2 cinsumption | well maintained - increased extraction if blood supply changes

Answer 34

Fick prince - ICG - co also Dye removed circ only in liver - total excr bile doesnt have enterohepatic circulation level blood spect 805nm Dye given contatst infusion - steady concnetration - rate infusion = uptake Hep arter conc - same as peripheral artery Hep vein - determ sample catheter

Answer 35

measure 805 - isobest for hb - amount light absorb hb - not vary with oxygen reduced o2 & oxy absorb same wwavelength True sat not altered

Answer 36

1200-1300mls - 25% CO Majority 95% flow - cortex 5% medulla Measured clearance PAH - para aminohippurate low plasma conc - renal blood almost completely cleared PAH - PAH equal renal plasma flow RBF - can be calc if HCT known

Answer 37

Freely filtered at glomerulus & secreted - not reabsorbed Indicator cleared from blood single circulation Stable easy measure non toxic not cause alteration in flow PAH has properties also measure eceltromagnetic othery type flow meter

Answer 38

Fick principle underly principle - application law conservation matter Uptake substance tissue - difference amount entering = flow x art conc amount leave tissue flow x venous rearrangement Flow = uptake / a-v conc diff Kidney Renal plasma PAH uptake / renl art pah - ren ven pah Pah totally cleared - renoul venous pah - arterial not required - not taken up any tissue venous pah should be idntical Renal PAH uptake - urinary pah times volume produced Effective renal = urinary pah xbol urine / periph venous pah Insepction eqn reveals - same quation clearance UV/P Low pAH conc - not all PAH removed Correction factor convert effective renal plasma flow into renal plsam flow divide by 0.9 above 90% extraction PAH

Answer 39

sing plasma conc and plasma cleared pah - follows it is plasma not blood filtered glomerulus volume calculated is clearance volume PAH for PAH removed plasma

Answer 40

18mls/o2 min Renal blood suppl 25% co weight 0.5 body weight Renal o2 consumo 7% total baody consumpiton dont correalte kidney very meatbolic active high o2 consump compared weight RBF higher predicted oxygen consumtion - o2 extraction ratio low Tissues receive flow needed to carry out function most - oxygen metbolite maginatue flow - excretory & homestoatic functions - determine large blood rather than oxyegen consumption

Answer 41

MAP autoreg 75-105 Myogenic - glomerular arterioles tubuloglomeural feedback - involving juxtglom app Sitatuion myogenic mech -intrinsic mechansim - primary control rbf tubuloglomerular feedback - involved primary maintain constant filtration rate - effector vascon / vasodil afferent arteriole - assist maintain constancy of blood flow - indirect consqew

Answer 42

Imporatnt feedback autoreg GFR - too much fluid or electrolyte reaches early distal tubule - sensed macula densa - feedback signal vasocon - glomerual afferent arteriole decrease rbf and gfr = decreased delivery fluid * electrolytes in distal tubule Two componenets to tubuloglomerular feedback - feeedback signal cause vasocon / dil details - not fully elucidated signal sense macula desna - change na flux accross membrane change content early distal tubular fluid macula densa cells - compound acts signal vasoconstrictor mechanism act efferent arteriole - vasdil afferent - renin angII not fully workled Mech effect gfr change - few percent between map 80-160

Answer 43

Pressure dependent Mechnism autoreg GFR not perfect GFFR does increase little increase MAP Small increase GFT - a/w larger increase urine flow Estimated GFR - controlled controlle dfew percet maintain normal levels ater & solute reab / excretion Nt apprecated how tight control GFR - minimise change water & solute excretion Tight control GFR - water excretion vary w/ autoreg pressure rang Outside range - extremely large incrase/ decrease urine flow occur small perfect change is a lrage voulme change 5% increase gfr - 9L day large volume - too much reabsorb mainta noirmal volume Pressure diruesis - intrsice system control bp presure volume control system Effect change renal water na excrtetion response change art pressure Most imporatnt mech control blood vol - vital part pressure depend urin e flow autoreg urine flow - not consistent survival

Answer 44

20 mmHg similar coronary sinus

Answer 45

Norad - contrict renal vessle - interlobaeral artery & aff aterioles At II casocon - effect both aff + EFF arterioles PG = Increase cortex flow decrease medullary flow Ach - vasodilation

Answer 46

Smallest blood vessels in body smallest arterioles metaarteroles precap sphincter cap small venules arterioles - vascular sm major site sttem vasc resist many tissue remain closed wiout flow reserve capacity - open quickly local don fall po2 when addit flow reqd Some tissue - contaains direct av connex shunt flow under great control nervous system now partic tfer gas skin - heat regulation

Answer 47

sm metart - precapp contract & relax - intermittent flow in capillary - vasomotion local drop PO2 - impratnt factor rrelax precaiplly sphincter intermitt cap flow - not cycliac rise bp - flucation smooth out arterioles

Answer 48

System cap 5% lbood vol extreme imporatn - exchange water electolyte gas waste nutrient cap membrnn most drug need cross reach site action intracsular volume contaact ISF - baths all cells body transfer substance principl fucntion microcir Movement water accross cap membrane - 2 proccess diffusion filtration water molecuesl smaller size of pores in capilalry -c ross wall easily cross gap enotheilail cell electrole small mol - cross membrane thru pores - via intercell gaps lipidsouilbe sub - o2 co2 cross thin wall endothial cell protein large do not easily cross some transfer pinocytsosis

Answer 49

Water movement //t tow process diffsuion otal daily diffusion water across cap hgh 80000l day larger total cap blood flow co 8000l day Diffusional movement water large both direction not result net movement across cap - no osmotic gradient FIltration Accross capillar also occurs - ultrafiltration plasma proteins do not cross Imbalance hydrostitic & oncotiuc pressure - along capillary memnbrane - starlings hypotehsis UF 20ml min - body whol 18mls reabs in capillary rest retuend as lymph 2ml min No net movement water d/t diffsuion accross membrane net diffsuon depnd conc gradient - orinaryl no water cocn differece cap mebrane Filtration does = net movement water d/t imbalance between force out and inward - different times tissue net move in or out forces change in value along length capillary - typical sitaution net movement out at arterial end - net movement in at vbenous end

Answer 50

Large volume bidirection whole length concntration gradtion hydrostaic oncotic pressure - not involve reponso net movement gas nutrients waste - move down con grat

Answer 51

Ultrafiltration - protein not cross membrane volume msaller inward or outward at position along capillary net movement gover starling forces not important gas nutrient waste - is improitant water

Answer 52

Fluid movement d/t filtration accross wal cpaillary depend balance hydrostraic pressure gradient & oncotic pressure grdient across capillary Pc Pi Tc Ti hydrstrric capilary oncotic interstitium Net driving pressure = Pc-Pi - Tc - Ti Net fluid flux - proportional to net driving pressure Reflection coeff filtration coeff Capillary hydrostatic pressure falls along legnth of arterial to venous end driving pressure - decrease become neg

Answer 53

Correction factor - apply to measured oncotic pressure ghradient accross capillary wall Small leak protein accross capillary membrane two improtant effect Itnstertial fluid oncotic pressure higher than would be Not all protein effective retain water effective capillary oncotic pressure lower measured oncotic presure Both effect decrease pressure grad Instit oncotic pressure - acount included cal grad Used correct magnitaute of measuredgraident ake account ineffectives some of oncotic pressure grad 0-1 eg CSF & GF - low protein - reflection coeff close 1 Prtein cross wall hepatic sinusiod - protein cocn lymph high reflection coeff low - walls do not reflect all protein ack - formula for net driving pressure include reflection coeff

Answer 54

net flud flux d/t filtration across capillary wall - proportional to net drving pressure fitlration coefficient k is contstaing of proortioanlity in flux starling equn net flux = K x (net driving pressure) K x {(Pc-Pi)-d(Tc-Ti)} k fitlration coeff d reflection coeff filtration coeff two compnents net fluid flux depned area capillary walls where transfer occurs permeability capilary wall to water - K = area x hydraulic condcutivty leaky cpailly - high filtration coeff glomeuralr capilary all leaky naturally Filtration coeff - leaky capil membrane h20 reflection coeff - protein

Answer 55

Art end Venous end Pc 25 10 Pi -6 -6 Tc 25 25 Ti 5 5 Net driving pressure out at art end & ion venous end Change in net driving pressure d/t decrease capillary hydrostatic pressure - asummes reflection coeff high

Answer 56

sitatuion different remarkable body whole net uf reabso 2-4l day net excess capil gfr - 180l Gloemrueres Filtration coeff hih - high perm water reflection coeff high - 1 filtrate true ultrafiltre - essent imperprotein - oncotic pressure filtrate 0 hydrostat pressure in capill high - not decerase along legnth large loss fluid & imperm to protein - onctoic pressure in capillary icnrease along length of capillary - Net outward filtration along whole legth capilary hydrostatic pressure gloermural capill affect balance aff & efferetn constriction

Answer 57

Balance twoard reabsoprtion cap hyrstic pressure lower - genreally lower pressure in PA

Answer 58

Cap membrane in cerebral Relatively impermeable to most low molecular weigh solutes present in blood as well as plasma proteins Ions N Cl make up most solutes solutes effective exert osmotic force acrros menbrae Starling force cerbral cap & hyydrstat pressure and osmotic pressure d/t effective solutes oncotic pressure small vs high osmotic pressure effectgive samll solutes small leak solutes - reflection ceoff - plasma & other cap bed 1 milosm increase icrease osmotic gad bl and brain exert 17-20mmhg small change tonicity marked effect on cerebral vol

Answer 59

Gas exchange Moves pulmonary blood flow close a/w alverolar gas at bl gas barrier - gas exchange facil large amt of flow pulmonary = co Membrane thin - Large surface area 1 Pul capil - thin wall Alv wall - cap dense network - continous film blood - large cap surf area pressure pulm lower - system - pvr low - pressure sufficent perfuse apical areas - erect healthy adult

Answer 60

Cap hydrostat 13 art 6 venous - vary effects gravity erect lung instital hydrostatic pressure - vary 0 to negative value Cap oncotic pressure 25mmh instital oncotic 17 - est collection lung lymph Oncotic pressure grad - interstital - oncotic pressure high - signif protein leak - albumin - normal circ - refecltion coeff low - est 0.5 Considering typical value -e st net oncotic snmall - favours reabsorption Hydrostatic press grad capil - intra alv vessel [ presure expose close alv pressure - actual measure - slight neg - closer holum more neg - favour flow alverolar intestium into lymphatics

Answer 61

Capillary hydrstatic pressure vary - effects gravity erect lung - suspend gravitato field - pressure veseel high than apex pressure difference - static water column Distance 30cm 0 pressur diff 30 typical pa press 25/8 Pressure barely adeq - prefusion apex low resistiance - half d/t capil - no muslce wall cap hydrstoatic quicl;y affect change pap & lap without buffer normal - smell net forward movement fluid est = pulmonary flow rate use 10-20mls hr

Answer 62

not uself - not possible measure value estimate - plasma protein as index cap oncotic and pa cather

Answer 63

Large surf area & thin walls - faciliatte filtration cap to interstitum intertsil moves wtoward hilum along space beside vessel airway hydrostaitc instet - more neg apporaching hilum - excess filtrate removed lymphatics flow premoted vetilatiy cycle & 1 way valves

Answer 64

For it to occur - excess fluid accumulate in iterstitum - then move into alvoeli lung resistant - usually absorbed 1 increase lymph flow - increase filt increase flow 2 decrease intertstitial oncotic pressure - oncotic buffering filtration icnrease - albmuin loss in filtrate decrease - combined increased flow 0- washses albumin out interstitum & interstitial oncotic pressure decrease 3 High interstitial compliance Large volume fluid - acumulate gel intestium without much pressure rise tissue full fluid - pressure rise - alveolar flooding bathtub effect - analogy tub take lot fill - point full suddnely overlys safety - effective capillary hyosratic rise x3 before flooding surfactant also has a protective role

Answer 65

Tissue ability regulate own blod suplly - so recieved bloof flow requires for function intrinsic & local - each tissue eprate nervus/ humoral factors affect arterioal resistance Heart brain kidney - low neurogenic control circ 45% co to them Pressure autoreg metabolic autoreg

Answer 66

blodo - tissue cosntant despite change system art pressure blood flow - most tissue require dont alter w/ rise fall pressure - tissue arteriolar resitrance change to compenase & hold flow coontsant - effective wide range map - many tissues cerebral blow flow for 50-150 in carotid Myogenic mech increase pressure - increased strethc walls - vascular SM - repond contract increased tone locally l- increase resist -drop blood flow Uterine cirulatuion during preg vasc bed preg utereus flully dilate - autoreg not present uter blood flow late preg pressure depenedent - anaethit implication decrease half normal before oxygenation affect Hepatic portal supply venous drain bowle - not autoreg liver- heaptic art supply autoreg

Answer 67

Varies depending on metabolic needs of organ or tissue active nearly all tissues all times- vasoidlator mediator considered cause identiy not est certrainty mos ttissue possible adnosie nitric h ion increase demand blood 0- increased metabolic activity - local increase in mediator - causes local arteriolar vasodilation increase blood flow