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CVPR: CV Unit I > Hemodynamics > Flashcards

Flashcards in Hemodynamics Deck (28):
1

Mechanism of blood flow through vessels

-pressure differences drive blood flow through vessels
-difference between arterial and venous pressure drives blood flow through organ

2

Location of highest pressure and highest resistence

-high pressure @ aorta
-largest drop in pressure/highest resistance @ arterioles

3

Total blood volume

~ 5L

4

Location of greatest blood volume

-venous system = "capacitance vessels"

5

Flow definition w/in context of CV system

-(Q)=volume per unit time (ml/min)
-constant throughout closed system

6

Cardiac output definition

-total flow in CV system

7

Velocity definition w/in context of CV system

-(v)=distance per unit time (cm/sec)
-inversely related to cross-section area (A)
-velocity high w/small A (i.e. aorta) & velocity low w/high A (i.e. capillaries)

8

Flow equation

-Q=P/R
-Q=flow
-P=pressure difference
-R=resistance
-aka CO=(mean arterial pressure - mean venous pressure)/total peripheral resistance (TPR)

9

Poiseuille's Equation

-Q=P x (pi*r^4)/(8nl)
-Q=flow
-P=pressure difference
-r=radius
-l=length
-n=viscosity of blood

10

Resistance of vessels in series vs. parallel

-total resistance of vessels in series is higher than any individual vessel
-total resistance of vessels in parallel is less than the vessel with the smallest resistance

11

Laminar flow definition

-smooth, streamlined, most efficient
-velocity slowest at edge, fastest at center

12

Turbulent flow definition

-irregular
-requires more pressure for same average velocity (vs. laminar)

13

Factors that increase turbulent flow

-large diameter
-high velocity
-low viscosity
-abrupt diameter change
-irregularities on tube walls

14

Pulsatile flow

-heart pumps intermittently--pulsing flow through aorta; pressure is not constant

15

Systolic vs. Diastolic pressure

-peak aortic (~arterial) pressure vs. minimum aortic pressure

16

Pulse pressure definition

-pulse pressure=systole - diastole= 120 - 80 = 40mmHg

17

mean arterial pressure (MAP) definition

MAP ~ diastolic + 1/3(systolic - diastolic)

18

Compliance definition/equation

-C=(change in V)/(change in pressure)
-represents the elastic properties of a vessel
-determined by proportion of elastin to collagen

19

Arteriosclerosis

-loss of compliance cause by thickening/hardening of arteries
-some normal comes w/aging

20

LaPlace Law equation

-T=(P*r)/u
-T=tension
-P=transmural pressure
-r=radius
-u=wall thickness

21

Pressure/radius impact on Tension (i.e. in LaPlace Law)

-Tension increases w/increasing pressure and radius --> hypertension increases stress on vessel/chamber walls

22

Transformation of pulsatile flow --> continuous flow

-degree of compliance in main arteries contributes to transformation of pulsatile flow deriving from heart to continuous flow @ capillaries

23

Major types of transport of CV system

-bulk transport=cargo brought from point A to B
-transcapillary transport=movement of cargo between capillaries and tissues

24

Fick's principle definition and equation

-considers how much of a substance is used by a tissue
-x(used)=x(in)-x(out)=Q([x]in - [x]out)

25

Hydrostatic pressure definition

- ~blood pressure
-net hydrostatic @ capillaries: difference between pressure and interstitial pressure
-promotes filtration

26

Oncotic pressure definition

-osmotic force created by proteins in blood and interstitial fluid
-alpha globulin and albumin = major determinants of oncotic pressure
-solutes move from high to low concentration vs. solvents move towards high concentration
-promotes reabsorption of fluid

27

Starling equation

-Flux=k[(Pcap - Pint) - (Ocap - Oint)]
-k=constant
-Pcap=cap hydrostatic pressure
-Pint=interstitial hydrostatic pressure
-Ocap=cap oncotic pressure
-Oint=interstitial oncotic pressure

28

Net flux fluctuations @ capillary bed

-factors that increase hydrostatic (blood) pressure (hypertension) or reduce oncotic pressure (liver disease) --> excess filtration --> edema
-arterial end=more filtration vs. venous end=more reabsorption
-different net flux at different cap beds