Systemic Circulation and Hemodynamics Flashcards
Arteries have ____ flow and ____ pressures
HIGH
Arterioles can moderate pressure because they have a lot of ____ in their walls
Smooth muscle
Capillaries have what important quality?
LARGE cross-sectional area
Veins have ____ flow and ____ pressures
LOW
Veins have what important quality?
Act as a storage reservoir; LARGE volume
What is the equation for Flow (Q)?
Pressure gradient/Resistance
If you increase resistance, what effect will that have on the flow?
DECREASE flow
If you decrease resistance, what effect will that have on the flow?
INCREASE flow
Resistance is directly proportional to what?
Viscosity
If you increase viscosity you will do what to resistance?
INCREASE
Resistance is indirectly proportional to what?
Radius (diameter) of the vessel
If you increase the radius of a vessel you will do what to resistance?
DECREASE
If you increase the radius of a vessel, what effect will that have on the flow?
Increased radius = decreased resistance = increased flow
If you decrease the radius of a vessel, what effect will that have on the flow?
Decreased radius = increased resistance = decreased flow
Ratio of RBC:plasma in the blood
Hematocrit
Increased hematocrit increases ____
Viscosity
Increased viscosity will increase?
Resistance
– and thus decrease flow
Hematocrit is usually around 40-50% and is higher in what gender?
Males
Adding resistance beds in series ____ resistance
INCREASES
Adding resistance beds in parallel _____ resistance
DECREASES
How are capillary beds arranged, in series or parallel and what is the corresponding resistance?
They are arranged in parallel = low resistance
Flow is the same as?
Cardiac output
What is the equation for Cardiac Output (flow)?
Arterial pressure - Venous pressure / TPR
TPR
Total Peripheral Resistance
Where is the site of greatest control of blood flow and TPR?
Arterioles!!
Increased Sympathetic tone does what to TPR and flow?
Vasoconstriction
- INCREASED TPR and DECREASED flow
Decreased Sympathetic tone does what to TPR and flow?
Vasodilation
- DECREASED TPR and INCREASED flow
What is the equation for Velocity?
Flow / Cross-sectional Area
Where will velocity be high?
Arteries
Where will velocity be low?
Capillaries - due to the HIGH CSA!
When velocity is HIGH the blood flow may become ___
Turbulent
What predicts when turbulence will occur?
Reynold’s Number