13: Systemic Circulation And Hemodynamics Flashcards
Where is stressed vs unstressed volume
Stressed: arteries
Unstressed: veins
Pressure and flow in arteries
Relatively high
Walls of arterioles
Muscular, contract to control flow
Site of greatest control of blood flow and TPR
Arterioles
Where is the largest CSA?
Capillaries
Largest blood volume is found where?
Veins
What happens when diameter of a vessel increases?
4 fold increase in flow
Hematocrit
Ratio of RBCs to plasma in blood
Change in resistance when adding resistance beds in series vs parallel
In series: increases resistance
In parallel: decreases resistance
Are capillaries in series or parallel?
Parallel
Where is velocity high and low?
High in arteries, low in caps
Where is compliance highest and lowest?
Highest: veins
Lowest: arteries
Compliance is the reciprocal of what?
Elastance
Where is the largest pressure drop in the vessel system?
Arterioles
Greatest and lowest BPs
Greatest: systolic: ~120
Lowest: diastolic: ~80
Pulse pressure calculation
SBP - DBP -> 40 mmHg
MAP calculation
1/3 (SBP) + 2/3(DBP)
MAP when BP is 120/80
93.3 mmHg
What increases and decreases in arteriosclerosis?
Increases: SBP, MAP, pulse pressure
Decreases: compliance
Aortic stenosis: what increases and decreases
Decreases: SBP, MAP, pulse pressure
What does increased TPR do to pulse pressure curve?
Shifts entire curve up with no change in shape
Three ways substances are exchanges thru cap wall
- Clefts
- Diffusion
- Vesicles
What passes thru clefts in caps?
Water-soluble substances like lactose, electrolytes, etc.
What passes thru caps via diffusion?
Lipid soluble substances like O2 and CO2
Vasomotion thru caps
Is oscillating so that blood isn’t constantly flowing thru caps
What causes oscillation in caps
Metarterioles, precap sphincters
What causes change in starling equatino / fluid enhange
Net forces that influence movement of water, intravascular and interstitial pressure
What do Pc, pi c, Pif and pi if stand for?
Pc: capillary hydrostatic pressure
Pi c: capillary osmotic pressure
Pif: interstitial hydrostatic pressure
Pi if: interstitial osmotic pressure
Reactive vs active hyeremia
Reactive: occurs after tissue blood supply is blocked for a short time
Active: occurs when tissue metabolic rate increases
Which is stronger, epi or norep?
Norep
