Factors affecting flow through tubes Flashcards
Define pressure.
Force exerted per unit area
Define pressure gradient.
The difference in forces exerted (per unit area) at either end / side of an object e.g. a tube or membrane
Define flow.
The volume of fluid passing a given level of the circulation / airways per unit time
Define velocity.
The rate of movement of fluid along a vessel / airway
Define resistance.
A force that tends to oppose the flow of a substance
What is flow generated by?
A pressure gradient
Describe Ohm’s law for fluid dynamics.
Flow = pressure gradient / resistance
What does Boyles Law state?
At a given temperature, the pressure and volume of an ideal gas are inversely proportional
How is pressure gradient calculated?
deltaP = Q x R
Apply the formula P = Q x R to the cardiovascular system.
Mean arterial pressure – central venous pressure = cardiac output x systemic vascular resistance
Where is velocity at the lowest and highest in laminar flow?
Lowest at edges. Highest at centre
Which 3 factors affect resistance?
Radius
Length
Viscosity
Give the equation for calculating resistance.
R = 8nl / pier4
Describe Poiseuille’s Law on affect on flow.
Q = deltaPpier4 / 8nl
Flow is directly proportional to which power of the radius of a tube?
Fourth
