Lecture 15: Hemodynamics and Systemic Circulation Part I Flashcards
Which vasculature has the highest and lowest pressure?
Highest pressure: arteries
Lowest pressure: veins
Which vasculature has the highest amount of volume for blood?
Veins (65% total blood volume)
When veins constrict, what happens to the blood?
Can move blood to arterial side to increase blood pressure
*change in volume but not much with resistance
When arteries constrict, what happens to the blood?
There is a change in resistance but not much with volume
How do you calculate the velocity of blood flow?
Velocity = Flow/Area
How do you calculate blood flow?
Flow = Pressure Gradient/Resistance
How do you calculate cardiac output?
Cardiac Output = (Arterial - Venous Pressure)/Total Peripheral Resistance
What factors can affect resistance?
Viscosity
Length of Vessel
Radius of Vessel (biggest factor)
Adding resistance beds in series _____ resistance
Adding resistance beds in series INCREASES resistance (the longer the tube the higher the resistance)
Adding resistance beds in parallel _____ resistance
Adding resistance beds in parallel DECREASES resistance (the more divisions the blood goes through, the less resistance)
What is laminar flow?
Smooth blood flow with little turbulence (high velocity in center and lower velocity in the sides)
<2000
What is the Reynolds number equation?
Reynolds Number = (density x diameter x velocity)/Viscosity
*Becomes more turbulent is there is an increase in density, diameter, velocity or decrease in viscosity
What is compliance?
How easy for vessel to expand
What is the formulate to calculate compliance?
Compliance = (Δvolume)/(Δ pressure)
Which type of blood vessel has the greatest compliance?
What vessel has the lowest compliance?
Veins
Arteries, even lower when arteries are aged (as in atherosclerosis)
When veins constrict, what happens to its compliance?
Volume is reduced so compliance decreases
- blood shifts to arterial side, increasing arterial blood pressure
- can change diameter and compliance stays the same
Why is there a pulsatile nature in the blood pressure from aorta to small arteries? How does this relate to systolic and diastolic pressures?
Due to compliance and distension during ejection and recoil during diastole
Systolic is highest pulsatile point and diastolic is lowest pulsatile point
How do you calculate pulse pressure?
Pulse Pressure = Systolic - Diastolic
How do you calculate mean pressure?
Mean Pressure = Diastolic + ⅓ Pulse Pressure
How does blood volume in lungs compare to aorta?
How does resistance and pressure in lungs compare to aorta?
- same
- both lower in lungs than aorta
If there is a decrease in compliance, what would happen to pulse pressure?
It will increase (mostly the systolic pressure, diastolic will stay the same or decrease)
*think about compliance formula
If there is a increase in resistance, what would happen to pulse pressure?
Stays the same
-if cardiac output and stroke volume stays the same
How is left atrial pressure measured?
Why?
Use a catheter through jugular vein –> RA –> RV –> pulmonary vein and blow up a balloon
- pressure measured here is related to Left Atrium pressure
- good sign of cardiac failure
What is cardiac failure?
Left ventricle cannot properly pump blood efficiently
