Lesson 19 (Part 3) Flashcards
What is the driving force behind fluid flow?
Pressure
What is the formula for pressure?
P = F/A P = pressure F = force A = area
What is pressure difference required for?
Fluid to flow
What is a pressure difference also known as?
Pressure gradient
What is the formula for pressure gradient?
Delta P = P2-P1
What is the unit for pressure? (2)
- Pa
2. N/m^2
How does fluid flow?
From an area of high pressure to an area of low pressure
What does Q represent?
Volumetric flow rate
Volumetric flow rate?
Volume of blood passing a point per unit of time
What is the unit for Q?
mL/s
What is the formula for volumetric flow rate?
Q = delta P/R Q = volumetric flow rate P = pressure R = resistance
What is Q applied?
To a long straight tube
What is the formula for resistance?
R = 8Ln/pie r^4 R = resistance L = length of tube (cm) n = viscosity r = radius (cm)
What happens to the resistance when the length of the tube increases?
It increases also
- longer the tube the higher the resistance
What happens to the resistance when the viscosity increases?
It increases
- the higher the viscosity the higher the resistance
What happens to the resistance when the radius increases?
It decreases
Viscosity
Resistance to flow offered by a fluid
What is the unit for viscosity?
Poise
What is the viscosity of anemia compared to polycythemia?
It will be lower
What has the strongest effect on resistance of all the parameters?
Radius or diameter
What happens to the resistance if the radius doubles?
Resistance decreases by 16x
Vasoconstriction
Smaller blood vessels, so it restricts the blood flow
Vasodilation
Larger blood vessels, which allows more blood flow
- when it is needed
What is Poiseuille’s equation?
Q=deltaP pie d^4/128Ln
- long straight tube
What is the formula for radius?
r = 1/2d r = radius d = diameter
