Topic 11: Cardiovascular System - Blood Circulation Flashcards
What is blood flow?
- volume of blood flowing through any tiswsue/min
- ml/min
What is blood flow in a vessel determined by?
- pressure and resistance
What is the formula for blood flow?
F = deltaP/R
where
F=flow
deltaP = blood pressure gradient (difference) between 2 points
R=resistance
In terms of BP gradient, where does blood pressure decrease from?
decreases from aorta to arterioles (resistance vessels) to large veins (capacitance vessels)
What is resistance?
- opposes flow
- friction of blood rubbing against vessel walls
What does resistance depend on? (3)
- vessel length
- blood viscosity
- radius of arterioles (major resistance vessels)
Which factors that determine resistance normally do not change? (2)
- vessel length
- blood viscosity
how are radius of arterioles controlled by?
- smooth muscle innervated by SNS
vasodilation and constriction
What is blood flow to organs controlled by?
- vasoconstriction and vasodilation
What occurs in vasoconstriction in terms of radius of arteriole, resistance, and flow?
- decreased radius
- increased resistance
- decreased flow
What occurs in vasoconstriction in terms of pressure in artery and organ?
- pressure in artery increases (backs up)
- pressure in organ drops (less blood flows into organ capillaries
What occurs in vasodilation in terms of radius of artery, resistance, and flow?
- increased radius
- decreased resistance
- increased flow
What occurs if vasoconstriction/dilation is local (ie. to one organ)?
- no observable change in systemic (arterial) BP
What occurs if vasoconstriction/dilation is systemic?
- systemic BP will change
- note systemic is entire body
