Lecture 10: Overview of Circulation Flashcards
What is systolic arterial pressure in the systemic circulation?
120 mm Hg
What is the diastolic arterial pressure in the systemic circulation?
80 mm Hg
What is the pulmonary artery systolic pressure?
25 mm Hg
What is the pulmonary diastolic pressure?
8 mm Hg
What are the functional parts of the arteries?
arteries arterioles capillaries venules veins
What do the arteries do in circulation
transport under high pressure
What do the arterioles do in circulation?
control conduits
What do capillaries do in circulation?
exchange between blood and extracellular fluid
What percent of blood volume is in the systemic circulation?
84%
What percent of blood is in the veins?
64%
What percent of blood is in the arteries?
13%
What percent of blood is in the systemic arterioles and capillaries?
7%
What percent of blood is in the heart and lungs?
16%
What is the equation for velocity of blood flow?
V= F/A
F= volume of blood flow A= cross sectional area
Rate of blood flow to each tissue of the body is almost always precisely controlled in relation to what?
to the tissue need
The cardiac output is controlled mainly by _______
sum of all the local tissue flows
Arterial pressure regulation is generally independent of either ________ or _________
local blood flow
cardiac output control
What is pressure gradient?
pressure difference between the two ends of a vessel
What is resistance?
impediment to blood flow through the vessel
Ohm’s law
F= change in pressure/ resistance
What is the overall blood flow of an adult at rest?
5000 ml/min
Laminar blood flow = _________ flow
streamline
In laminar flow, the velocity of fluid flowing in center is _______ than that of fluid flowing towards outer edge
greater
what is turbulent flow?
nonlayered flow
Turbulent flow creates _____ and produces more _____ than laminar flow
murmurs; resistance
When does turbulent flow occur?
when flow is too great
when blood passes an obstruction with the vessel
when blood has to make a sharp turn
when flood passes over a rough surface
Tendency for turbulent flow increases in ______ proportion to velocity of blood flow
direct
Tendency for turbulent flow increases in ______ proportion to diameter of the vessel
direct
Tendency for turbulent flow increases in ______ proportion to density of the blood
direct
Tendency for turbulent flow increases in ______ proportion to viscosity
inverse
Laminar flow equation
Re= (vdp)/ n
v= mean velocity of blood flow d= vessel diameter p= density n= viscosity
What is Re?
Reynolds number, the measure for the tendency for turbulence to occur
When Re rises above 200-400, turbulent flow will occur in _____ regions of a vessel
some
When Re rises above 2000, turbulence will even occur in _____ vessels
straight
What is blood pressure?
the force exerted by the blood against any unit area of the vessel wall
What can pressure be measured with?
mercury manometer
electronic transducers
What is resistance?
impediment to blood flow in a vessel
What variable determine resistance?
vessel radius
blood viscosity
vessel length
What is cardiac output?
rate of blood flow through entire circulatory system, 100 ml/sec
What is the pressure difference from systemic arteries to systemic veins?
100 mm Hg
In conditions when vessels are strongly constricted, total peripheral resistance may rise to _____
4 PRU
When vessels are greatly dilated, the resistance can fall to as little as _____
0.2 PRU
What is the mean pulmonary arterial pressure?
16 mm Hg
What is the mean left atrial pressure?
2 mm Hg
What is conductance?
measure of blood flow through a vessel for a give pressure difference
conductance is ______ proportional to diameter
directly
What is Poiseuille’s Law?
V = π p r4 / 8 η l
What is the equation for resistance for blood vessels arrange in parallel
1/Rtotal= 1/R1 + 1/R2 +1/R3…..
What does amputation of a limb or removal of a kidney do?
removes a parallel circuit:
reduces total vascular conductance
reduces total blood flow
increases total peripheral vascular resistance
What circulations are arranged in parallel?
brain kidney muscle gastrointestinal skin coronary circulation
What is viscosity?
measure of the fluid’s internal resistance
Greater the viscosity, ______ the resistance
greater
What is the prime determinant of blood viscosity?
hematocrit
Anemia _____ viscosity
decreases
Polycythemia _____ viscosity
increases
