principals of blood flow Flashcards
what is the dichrotic notch
it is a small dip caused by the backfilling of the aortic valve as it closes
(seen in the pressure vs time graph)
what stage in blood flow does this statement describe:
“steady, laminar flow in rigid vessels
static driving pressure”
stage 1
what stage in blood flow does this statement describe:
“microcirculation and diffusion”
stage 4
what stage in blood flow does this statement describe:
“elastic vessel walls and pulsatile pressure”
stage 3
what stage in blood flow does this statement describe:
“high reynold’s number flow turbulence
dynamic pressure”
stage 2
describe the flow in series
constant flow
Q=Q1=Q2…
describe the blood flow in a parallel circuit
the volume flows are additive
Q= Q1+Q2…
what is the units for blood flow?
L/min
does this statement apply to series or parallel circuits?
“Blood flow is the same across any TOTAL cross sectional area of a system”
this statement applies to BOTH circuits
took me awhile to get it, page 157 in the notes can help
list 2 examples of blood circulation in our body that are in series
- the splenic and mesenteric vascular beds are in series with hepatic circulation
- renal glomerular and tubular circulation
how is flow distribution controlled?
by the adjustment of resistances (precapillary sphincters and arterioles) located prior to the capillary beds
where are the 3 biggest changes in tissue supply noted regarding blood flow during exercise?
- skin
- muscles
- heart
define velocity
rate of displacement of a PARTICLE of fluid with respect to time
define flow
give the equation for flow
rate of displacement of VOLUME of fluid with respect to time
Q= A x v
for an incompressible fluid in a closed system of rigid tubes what value stays constant; flow (Q), velocity (v), cross sectional area (A)?
flow! (Q)
define transit time
the time required for blood cell to travel between two points in the system
list 4 assumptions we sometimes make when dealing with blood as a fluid
- that it is a steady flow of incompressible fluid
- it is flowing through rigid, straight cylindrical tubes (besides for smaller vessels)
- the flow is laminar with no slippage
- the viscosity of the vessel wall is constant through out
what supplies the energy needed for blood flow
the driving/contraction force of the left ventricle
this pressure propagates throughout the circulatory system (because the blood is incompressible and continuous)
list two types of frictional forces that act on the blood flow in circulation
- resistance to flow coming from the walls of the vessels
- the viscosity of the blood
what causes vasoconstriction of the vascular smooth muscle?
sympathetic stimulation by postgang adrenergic fibers releasing norepi
explain the relationship between temperature and blood viscosity
they are inversely proportionate
The colder you are, the higher the blood viscosity (ex when shoveling snow, you have decreased blood flow, leading to decreased heat loss)
describe the pressure drop along the length of veins
gradual
describe the pressure drop along the length of small arterioles and capillaries
rapid
in regards to high or low viscosity, vessel length and radius where will the the greatest pressure drop be seen?
longer vessel
higher viscosity
smaller radius
describe the resistance of blood flow in series
additive
R (total)=R1 + R2 + R3…
describe the total resistance for blood vessels in parallel
1/R (total)= 1/R1 + 1/R2 + 1/R3…
the total resistance is less than any element in the network
