Flashcards in Circulation Part 2 Deck (20)
What is determined by the fick principal and the indicator dilution?
determination of flow
What do venous occlusion plesthymography, doppler ultrasonic flowmeter and vascular flow cuffs have in common?
all contribute to determination of vessel flow
What is the 3 port system of the Fick Principal?
Input blood concentration of substance x
Output blood concentration of substance x
Addition/removal of substance x from tissue (see fig 20-18 in Guyton)
amount of substance per min divided by the AV difference is equal to what?
T/F: Indicator dilution is based on conservation of mass.
See figure 20-19
What is distensibility?
the ability of a vessel to stretch (distend)
What is compliance?
The ability of a vessel to stretch and hold volume
What is associated with a small change in volume in systemic arteries?
a large change in pressure
What is a large change in volume in systemic veins associated with?
a small change in pressure
T/F:Systemic arteries are about 8X more distensible and 24 X more compliant than veins.
False; swap veins and systemic arteries
Local blood flow is regulated in proportion to what?
the metabolic demand in most tissues
T/F: Short term control of blood flow involves changes in tissue vascularity.
False; this is true of long term control; short term control involves constriction/dilation of vessels
Which type of control of blood flow is associated with vascular endothelial growth factor and angiotensin?
long term control
T/F:Arterioles act as an integrator of multiple inputs regarding control of flow.
T/F:Arterioles are richly innervated by SNS vasoconstrictor fibers and have beta receptors.
False; they have alpha receptors
T/F: Short term Local control of flow involves vasoconstriction/vasodilation of precapillary resistance vessels.
Explain the Local Vasodilator Theory.
Active tissue releases local vasodilator (metabolites) which relax vascular smooth muscle
Explain Oxygen demand theory.
As tissue uses up oxygen, vascular smooth muscle cannot maintain constriction.