9/18b Cardiac Physiology (Biomedical Sciences) Flashcards
• Apply the principles of hemodynamics to describe the relationships among flow, pressure, and resistance throughout the cardiovascular system. • Discuss the mechanisms that control the distribution of blood flow • Describe the mechanisms that regulate arterial pressure in the short and long term • Describe the cardiovascular responses to the stress of exercise
To meet rang of metabolic needs of the heart, we must regulate
- output of the system (CO=HRxSV)
- Distribution of output (vasculature)
Rigid tube with pressure transducers on left and right sides.
When pressure on left and right sides are the same, what is the flow
ZERO FLOW because no pressure gradient
Rigid tube with pump and pressure transducers on left and right sides.
When pressure on left is more than the pressure on the right and there is a pump in between what is the flow?
Fluid flows from left to right
How do you find the Total peripheral resistance (TPR)?
TPR = (delta P)/Q OR MAP/CO
Rigid tube with pump and pinched at the bottom and pressure transducers on left and right sides.
What is happening if the Q is the same?
- Increasing resistance because we are decreasing the diameter
- radius^4, small change in radius yields a huge change in resistance
- Pright increases
- Pleft decreases because there is less flow into the left side
Rigid tube with pump and split into 100 at the bottom and pressure transducers on left and right sides.
What is happening if the Q is the same?
-if there’s a 10-fold increase in resistance, then we have a 10-fold increase in pressure gradient
when we increase resistance and need to maintain flow, what do you have to do?
INCREASE the pressure GRADIENT, but how do you get the new pressure gradient?
-if there’s a 10-fold increase in resistance, then we have a 10-fold increase in change in pressure gradient
Blood pressure across the system
- Pulmonary Circuit blood pressure
1. Large Arteries: 15
2. Arterioles:
3. Capillaries: 10
4. Large Vein: 8
5. Atrium: 2-5 - Systemic Circuit blood pressure
1. Large Arteries: 90-100
2. Arterioles: 50
3. Capillaries: 20
4. Large Vein: 4
5. Atrium:0-2
What is Q an index of?
Q = delta P/R CO = BP/TPR
what is the BP pressure gradient from one side of the system to the other side?
90-100 mm Hg
Large pressure drop in a region of a system, means
there must be a large resistance
Biggest pressure drop is at what level?
at the level of the arterioles because the arterioles are the greatest source of resistance to flow in the CV system and a key determinate of TPR
If we want to affect TPR, what do we act on?
Arterioles!
If the flow in the systemic circuit is 5l/min the pulm flow is the same too? T/F
TRUE
What determines how much blood a particular organ gets?
Arterioles! decrease blood flow to a given organ -constrict arteriole -decrease radius -increase resistance -decrease flow