Cardiovascular System - Lecture 7 Flashcards
What kind of waves does the heart propagate?
un-damped
What happens to colliding waves of the heart?
they block
What was the phenomenon that Mines was exploiting in his experiment?
if you take a chunk of heart muscle out, you will have heterogeneity and some cells will have a slightly longer refractory period than other
How many times does the heart beat per second?
1
How long do the ventricles contract for during a heart beat?
1/3 of the period that the heart contracts
What is the pressure of the ventricle (L or R) compared to the aorta initially when the heart beats?
it is lower
When does the ventricle pressure stop increasing during a heart beat?
until it is greater than the aortic pressure
What happens after the ventricular pressure stops increasing during a heart beat?
the aortic valve opens
What happens to the pressure in the ventricles after the aortic valve opens?
it drops
What are the 5 steps after one of the ventricles beats?
- pressure in the ventricle is lower than the aorta
- pressure in the ventricle increases until it is greater than the aortic pressure
- aortic valve opens
- aortic pressure tracks ventricular pressure
- pressure in the ventricles starts to drop
What is the mean arterial pressure equal to?
100 mmHg
What is the formula for mean arterial pressure?
MAP = diastolic pressure + 1/3 pulse pressure
Why doesn’t the aortic pressure not drop to zero?
because of the Windkessel effect
What is compliance?
how easy it is to stretch out the muscular wall
How much of the cycle do the ventricles contract?
1/3
How much of the cycle is systole?
1/3
How much of the cycle is diastole?
2/3
How much of the cycle do the ventricles not generate pressure?
2/3
Why is the systemic pressure > 0?
due to the Windkessel effect
What is the formula for compliance?
C = change in volume/change in pressure
What does an aneroid sphygmomanometer measure?
the pressure in the cuff
What does an aneroid sphygmomanometer consists of?
a cuff with a bladder
an inflating bulb
a needle valve
an aneroid gauge
What is the difference between an aneroid sphygmomanometer and a mercury sphygmomanometer?
it uses a column of mercury instead
What are the 3 indirect ways to measure blood pressure?
palpation, auscultation, oscillometry