Lecture 29 - Cardiovascular System: Physiology of Blood Flow and Blood Pressure Flashcards
How will pressure gradient help with blood flow?
It will produce a force that moves fluid in the direction of lower pressure. Larger pressure gradient creates more force
What affects rate of blood flow?
Blood flow through a vessel is function of the opposing forces of pressure and resistance
How does resistance affect blood flow?
Resistance slows down the velocity/volume flow rate of blood caused by the friction between the walls of the tube and the fluid
T/F? Vessel resistance does not increase linearly with vessel length
False - it does increase linearly with vessel length. The longer the vessel, the more surface that’s in contact with blood, causing more friction
T/F? Vessel luminal diameter is inversely related to resistance
True - smaller diameter = larger resistance; more blood will be in contact with the smaller vessel wall
Does vessel diameter or vessel length have a larger impact on resistance?
Vessel diameter - change in diameter of a vessel will always produce a larger change in resistance than an equivalent change in length
What is viscosity?
A measure of resistance due to interactions among the molecules in the moving fluid
The more the molecules and materials suspended in the fluid interact with each other, the more viscous it is, causing internal friction -> slows down overall flow
How does turbulent (non-laminar) flow affect resistance?
It increases resistance
Laminar flow is when liquid is moving unidirectionally in smooth layers. In turbulent, these layers are disrupted and movement is not unidirectional, decreasing overall flow
How does turbulent flow occur?
Occurs due to shifts or changes in the geometry of the vessel wall:
- branch points
- tight curves
- irregular surfaces
Describe arterial pressure
It fluctuates with the changes in pressure due to the cardiac cycle - it is the highest during and just after ventricular systole, and lowest during diastole
How is blood pressure reported?
Systolic pressure/diastolic pressure
What is pulse pressure?
Difference between systolic pressure and diastolic pressure
What is mean arterial pressure (MAP)
Diastolic pressure plus 1/3 pulse pressure
How is blood pressure measured?
Measured through a cuff (sphygmomanometer) that tracks how much external pressure it takes to block blood flow
What do elastic arteries do?
They help buffer pulse pressure, reducing the variability in blood flow and pressures in capillaries
Arteries with larger amounts of elastic tissue stretch when blood is forced into them with high pressure, temporarily reducing blood flow rate