Vascular System Flashcards
How is Flow defined?
Vessel with the highest pressure (arterial(aorta)) minus Vessel with the least pressure (vena cavae) /R resistance
aorta - not measurable -> arterial
vena cavae - not easy to measure -> is very low -> 0
What affects resistance the most (see formula)?
radius, to the power of 4
Why is pressure in the vascular system fluctuating?
because ventricles and atrials are contracting (Systole) and relaxing (Diastolic)
What are Systole and Diastole?
The highest point of pressure = Systole
The lowest point of pressure = Diastole
When does the fluctuation stop?
right before the blood gets in the venous system
Where is the biggest drop in pressure?
In the arterioles, because they have the biggest increase in resistance
How do arteries react to an increased amount of blood pushed through them?
increased input of blood during systole in arteries -> arteries will stretch -> inflow > outflow
during Diastole the arteries shape gets back to normal, no inflow of blood -> outflow > inflow
What decreases the ability of stretching and dampening of arteries?
Arteriosclerosis
What is the mean arterial pressure MAP?
We don’t want fluctuation when measuring blood pressure ->
MAP (mean) = single blood pressure that produces the same flow
MAP formula!!! EXAM
MAP = Diastolic pressure - 1/3 * pulse pressure
MAP = Diastolic pressure - 1/3 (Systolic - Diastolic) !!!
How is flow through the cardiovascular system defined?
MAP / R -> KEY factor is r in R (resistance) power of 4
How can the diameter (radius) be regulated?
Smooth muscle cells surrounding arterioles
Smooth muscle contraction = Vasoconstriction (decrease in radius, increase resistance) Smooth muscle relaxing = Vasodilation (increase in r, decrease in resistance)
Vaso = vascular system (arteriols)
