Circulation Part 1 Flashcards
What is the main function of systemic circulation?
deliver O2 and remove CO2 and wastes
What part of circulation is designed to carry blood under high pressure out to the tissue beds?
systemic arteries
What parts of circulation act as control valves to regulate blood flow?
arterioles and pre capillary sphincters
How thick are capillaries?
1 cell layer thick
Where does exchange occur between tissue and blood?
capillaries
What do venules do?
collect blood from capillaries
What structures return blood to heart/dynamic storage?
systemic veins
T/F: blood flow is proportional to metabolic demand.
True
T/F; cardiac output is controlled by local tissue flow.
true
T/F: Arterial pressure control is dependent on local flow or cardiac output.
False; arterial pressure is independent of local flow or cardiac output.
how many layers of endothelium exist in blood vessels?
1
What are the components of blood vessels?
endothelium, elastic tissue, smooth muscle, and fibrous tissue
What vessel is composed moreso of smooth muscle, aorta or typical arteries?
typical arteries
What vessel is composed more so of elastic tissue, aorta or typical arteries?
aorta
What vesel is composed more so of fibrous tissue, aorta or typical arteries?
aorta, but its still more elastic tissue than fibrous.
T/F: veins are pretty much equally composed of elastic fibers, smooth muscle, and fibrous tissue.
True
What are capillaries composed of?
only endothelium
What is Ohm’s Law?
-V=IR (analogous to deltaP=FR)
Flow, Pressure gradient, resistance and Ohm’s Law are all components of what?
Hemodynamics
What is the term for the volume of blood that passes a certain point per unit time (eg. ml/min)?
Flow (F)
T/F: At a given flow, the velocity is inversely proportional to the total cross sectional area.
True F=velocityX
T/F: Flow is inversely proportional to the change in Pressure and directly proportional to resistance.
False; vice-versa: F=deltaP/R
The driving force of blood and the difference in pressure between two points, are both ways to define what?
Pressure gradient
T/F: Pressure gradient is proportional to flow.
True
What happens to resistance of flow when the pressure drops?
the resistance increases equally
What kind of circuit is systemic circulation (predominately)?
parallel circuit
What is usually solved for indirectly by measuring flow and deltaP?
Resistance
What is TPR?
Total peripheral resistance
What are the 3 advantages of systemic circulation being predominately parallel circuitry?
Independence of local flow control, minimizes TPR, and O2 rich blood supply to every tissue
What is the term for internal friction of a fluid associated with the intermolecular attraction?
viscosity
What is the viscosity of blood?
3
Viscosity of plasma?
1.5
Viscosity of water?
1
What is mostly responsible for the viscosity of blood?>
RBCs
what happens to blood viscosity when velocity is decreased?
increases
T/F:Fibrinogen decreases flexibility of RBCs.
False, actually increases flexibility
Cells can get stuck at constriction points momentarily. What does this do to the apparent viscosity?
increases
What is Hematocrit?
% of packed cell volume (primarily RBCs)
What is the normal range of hematocrit?
38-45%
Streamline, silent, most efficient, and normal all describe what kind of flow?
Laminar
Cross mixing, vibrational noise, least effective, and frequently associated with vessel disease (bruit) all describe what kind of flow?
Turbulent
What does Reynold’s number tell us?
the probability for turbulent flow (the great the R# the great the probability for turbulence)
velocitytube diameterdensity/viscosity=?
Reynolds numbers
R# = vDp/n
If R# is less than 2000 what kind of flow is it typically?
laminar
If R# is greater than 3000 what kind of flow is it typically
turbulent
T/F: Ultrasound is commonly used to determine velocity of flow.
true
During Doppler Ultrasound, if RBCs are moving toward the transmitter and therefore compressing sound waves, what is happening to the frequency of returning waves?
increase (Doppler frequency shift)
What kind of flow is a Broad band (ultrasound) associated with?
turbulent flow
What kind of flow is a narrow band associated with?
laminar flow
