Poiseuille’s Law
What factor determines flow speed the most in arteries?
Radius of the vessel
Based on Bernoulli principle. Velocity and pressure increase together. (True or False)
False. Velocity and pressure are inversely related
What is a stenosis?
A narrowing of a vessel
What is laminar flow?
Flow that is smooth and parallel throughout the vessel
What is resistence?
What makes it harder for blood to travel within a vessel
What power is radius raised by?
4th power
At the maximum velocity of a stenosis, what happens to the pressure?
Pressure decreases
What is viscosity?
How thick a fluid is
What is turbulent flow?
Flow that is chaotic and moves in random directions.
What factor makes the largest change in resistance?
Vessel radius
If there is an increase in blood viscosity, what happens to resistence?
Resistance increases (R∝η) Resistance is proportional to viscosity.
What happens to the velocity when blood moves through a narrowed vessel?
Velocity will increase (if flow rate remains the same)
True or False: Laminar flow is disorganized blood flowing in different directions.
False. That is the definition of turbulent flow. Laminar flow is an organized layer of flow.
Where are flow speeds the highest within a vessel?
At the center of the tube
What happens to resistence when blood is thick or thin?
Thick blood = increased resistance
Thin blood = decreased resistance
If the length of a vessel doubles while everything else remains the same, what happens to resistance?
Resistance doubles. Length and resistance are proportional.
What happens to the total energy when blood flows through a vessel without a change in velocity?
Total energy remains constant
What is the measurement for blood flow?
Q = Volume flow rate
What number does Reynolds have to be for turbulence to take place?
>2000
What is series resistence?
The total resistance across the entire vessel added together (The sum of all the resistances)
Vessel A. Vessel A is 1/16, while vessel B is 1/256. The bigger the radius, the less resistive it is. So based on Poiseuille's law, Vessel A will have more resistance.
Based on Bernoulli's principle, how is pressure and velocity related?
Inversely related
What is a pressure gradient?
The difference in pressure between two points that drives blood flow
What doppler setting is commonly used to analyze turbulence?
Appears as mosaic pattering under color doppler
What type of resistance describes the relationship of multiple pathways a vessel can travel? (If blood has more than one pathway to travel, resistance decreases.)
Parallel resistance