Hemodynamics

Question 1

Flow

Answer 1

Flow = change in pressure/ resistance

Remains constant throughout system

Question 2

Poiseulle’s Law

Answer 2

Flow = dP (pir^4)/(8mulength)
mu = viscosity
Radius is most important variable impacting flow

Question 3

How is pulsatile flow converted to constant flow?

Answer 3

Elastic aorta experiences pulsatile flow from LV
Pulsatile is dampened as it proceeds through system and energy is absorbed. Arterioles are major resistance vessels w/ more smooth muscle that convert flow.

Question 4

Compliance

Answer 4

dV/dP; vessel change in volume per change in pressure, the elastic property of a vessel that is determined by elastin content. Veins are more compliant than arteries, compliance decreases with age

Question 5

Law of LaPlace

Answer 5

Tension = (dP*r)/mu
mu is wall thickness.
Wall tension increases as pressure and radius increase and is reduced by thicker vessel walls

Question 6

Fick’s Principle

Answer 6

X consumed = [X]in - [X]out

Question 7

Hydrostatic and Oncotic pressure in capillaries

Answer 7

Hydrostatic pressure promotes filtration; higher on arterial side
Oncotic pressure promotes reabsorption; higher on venous side