Blood Pressure Flashcards
How is MAP estimated
usually roughly 100mmHg
Area under curve of pressure (look at cardiac cycle diagram)
The diastolic pressure + 1/3 pulse pressure
pulse pressure is systolic minus diastolic pressure
What determines MABP?
Cardiac output x TPR
What are the short term regulators of MABP?
Nervous activity mainly so effects of vasoconstriction and vasodilation, as well as effects on the heart so inotropy aletring SV and HR being altered
What regulates MABP in the long term
Fluid control by the kidneys, affecting CO mainly, not TPR
What influences aortic pulse pressure
Systolic: Stroke volume; aortic compliance
Diastolic: aortic compliance; run off from aorta ( TPR and heart rate)
How does compliance of blood vessels (namely the aorta) alter with age
It decreases, so as the vessel becomes more filled with collagen (more stiff), for a given volume the change of pressure is larger. Thus pulse pressure will increase (increase in systolic pressure)
How does TPR alter diastolic pressure
If you increase TPR, there is a less rapid run off, thus increasing diastolic pressure. vice versa. This will decrease the pulse pressure
Increased heart rate means higher diastolic pressure- less time for run off