13. CVS Physiology Flashcards
(41 cards)
What is the resting coronary blood flow?
250 mL/min
How much is coronary blood extraction?
Coronary O2 extraction is about 110 mL/L/min (55% of the available content)
Therefore supplies muscle that extracts 40 mL/L of oxygen per minute at rest
Do coronary arteries undergo autoregulation?
It autoregulates between a MAP range of 50-120 mmHg
What is the normal cardiac ejection fraction?
70%
What is the dicrotic notch represent?
rebound of the aortic valve
Normal LV end systolic volume?
30 mL
Normal stroke volume?
70ml
normal LVEDP
100 mm Hg
What can be used to measure pulmonary vascular resistance?
A Swan-Ganz catheter can measure cardiac output and PA pressure, enabling the PVR to be calculated.
- a flow-directed balloon catheter with a thermistor tip.
How does 5-HT affect pulmonary artery pressure?
5-HT produces pulmonary vasoconstriction, raising PAP
What is the mean pulmonary artery pressure?
What fraction is that of systemic circulation?
Mean PAP is 15 mmHg (around one sixth of systemic MAP), with both circulations having the same flow.
normally 25/10 mm Hg
The pressure drop is greater across major veins or major arteries?
They are similar in major vessels.
The largest drop is seen in arterioles.
The pressure drop across the hepatic portal bed is similar to that across the splenic vascular bed? T/F
False.
The hepatic portal bed is a very low pressure/low resistance one.
In the hepatic portal vein the pressure is approximately 3 times higher than that in the inferior vena cava.
T/F
False.
Normal hepatic portal vein pressure is 5-10 mmHg, little different from that in the IVC
How does the pressure drop between vary between pulmonary and systemic circulation differ?
The drop across the pulmonary circulation is only about a sixth of that in the systemic circulation.
in a CVP waveform, what does the ‘c’ wave represent?
The c wave occurs during early ventricular contraction (systole),
as the closed tricuspid valve bulges back into the right atrium.
What does the ‘a’ wave represent in a CVP waveform?
The a wave results from atrial contraction, so Is absent in AF
The a wave occurs in late diastole, long after aortic valve closure.
What does the ‘v’ wave represent in the CVP waveform?
The v wave occurs during diastole.
The v wave occurs during ventricular relaxation (diastole) but before the tricuspid valve opens.
Does the LV eject more blood per beat than the RV?
No, equal volumes.
During strenuous work, does the LVEDV increase or decrease?
Decreases because more blood will be ejected with increased ejection fraction.
At what RV pressure does the pulmonary valve open?
10-12 mmHg
LV pressure during diastole?
5 mmHg
What blood does the ductus venosus contain?
The ductus venosus contain blood returning from the placenta via the umbilical vein, oxygenated blood.
TRUE OR FALSE:
In fetal circulation - blood entering the right atrium can reach the systemic circulation without passing through the left side of the heart.
True.
Blood from the RA can reach the systemic circulation via the RV, pulmonary artery and ductus arteriosus.
It is mostly SVC blood that follows this pathway, which is largely kept separate from IVC blood via streaming in the RA.
