Cardiovascular Physiology 1 Flashcards
What is Hemodynamics?
The study of blood flow
What is the formula for blood flow?
F= 𝛥p/R
What is Resistance?
The friction that impedes flow
What are the units of flow?
mL/min
What are the units of pressure?
mmHg
What are the units of resistance?
mmHg/mL/min
What is the driving force for flow?
The pressure difference between two points
What must the relationship between the difference in pressure in order to have flow?
𝛥P>R
What is blood flow determined by?
The pressure difference between two points and the resistance to flow
What is the major mechanism for changing blood flow in the cardiovascular system?
Altering the resistance of the blood vessels
What portion of the flow equation cannot be measured directly?
Resistance, but it can be calculated
What is Blood Hydrostatic pressure?
The pressure that the volume of blood within our circulatory system exerts on the walls of the blood vessels that contain it
What happens to blood flow when there is no pressure difference?
There is no blood flow
What determines the Resistance to blood flow?
- Viscosity of the blood
- Length of the blood vessel
- Diameter of the blood vessel
Why can’t Resistance be measured?
Because it is determined by several factors
What is Viscosity?
The friction between molecules of a flowing fluid
Why is blood not considered a homogenous fluid?
It contains many things like electrolytes and proteins and formed elements
What are the Formed elements in blood?
RBCs, WBCs and Platelets
What is the Hematocrit?
The number of RBCs in the blood
What can change the viscosity of the blood?
The hematocrit
How does blood vessels Length and Diameter affect the viscosity?
They affect it by determining the amount of contact between moving blood and stationary wall of vessel
How is friction affected by blood vessel length?
A blood vessel with a longer length will produce more friction
In what physical way does blood flow through vessels?
In concentric layers
How does the orderly layer affect blood flowing through vessels?
It helps to reduce energy losses in the flowing blood by minimizing viscous interactions between the adjacent layers of the blood and the blood vessel
What is the relationship between viscosity, vessel length and vessel radius described by?
Poiseuille’s law
What is Poiseuille’s equation?
R = (8ɳl)/(πr^4)
What does R represent?
Resistance to blood flow
What does ɳ represent?
Viscosity of blood
What does l represent?
Length of the vessel
What does r represent?
The radius of the blood vessel
What is Resistance to flow inversely proportional to?
Radius of the vessel
What is the factor with the greatest effect on blood flow?
The radius of the blood vessel
