Circulation Flashcards
What are the 3 functions of Circulation?
- Transportation of nutrients to tissues
- Transporting waste products away from tissues
- Transporting hormones from one part of the body to another
Blood flow rate is controlled by
needs of the tissues
The kidneys need ____ blood flow than the ____
more; brain
All diffusion occurs here; most essential for determining what is needed
Capillaries
Arteries transport blood under ____ pressure to the tissues
high
_____ act as control conduits through which blood is released into the capillaries
arterioles
_____ exchange fluid, nutrients, electrolytes, hormones and other substances b/w the blood and interstitial fluid
capillaries
_____ collect blood from the capillaries and gradually coalesce into progressively larger veins
venules
What functions as conduits for transport of blood from venules back to the heart and is where 64% of blood is stored?
veins
Velocity is equal to
Flow / Area
The ___ volume of blood (F) much pass through each segment of the circulation each ___.
same; minute
Velocity (v) of blood flow is ______ proportional to the vascular cross-sectional area (A)
inversely
All blood vessels are
distensible
____ allows for the pulsatile output of the heart; smooth continuous blood flow through very small blood vessels of tissues
distensibility
Which vessel has the highest distensibilty?
Veins, because they hold 64% of blood
Mean Arterial Pressure (MAP)
(1/3 [SBP-DBP] + DBP)
Pulse Pressure
SBP-DBP
This type of pressure system extends from the left ventricle in contracted state all the way to systemic arterioles (CONTRACTED)
high pressure system
This type of pressure system extends from the systemic capillaries thru rest of systemic circuit, into right heart, then thru pulmonary circuit, into left heart, in relaxed state (RELAXED)
low pressure system
Blood flow to most tissues is controlled according to what?
the tissue need
What is the sum of all local tissue flows?
[Hint: it’s amount of blood pumped into the aorta each minute (STROKE VOLUME x HR)]
cardiac output
Arterial Pressure Regulation is generally independent of what 2 things?
local blood flow control OR cardiac output
Ohm’s Law states that F is equal to
Change in pressure / vascular resistance
As the blood increases in thickness (viscosity), disruption or turbulence
decreases
Systemic Vascular Resistance (SVR) is equal to
MAP / CO
The flow will dramatically increase if the _____ increases, since it is to the fourth power in the Blood Pressure Blood Flow equation
radius
Blood Pressure Blood Flow
Flow =Л r4 ΔP/8nℓ
Laminar Flow
Steady state flow through a long, smooth blood vessel; streamline flow (each layer of blood remains same distance from vessel wall); central most portion of blood stays in center of vessel
Turbulent Flow
Blood flowing in all directions in the vessel and continually mixing within vessel
According to parabolic velocity, flow on the outside moves _____ than flow on the inside
slower
Turbulent or disorderly flow can be created by (4)
- Rate of blood flow becoming too great
- Passing by an obstruction in vessel (plaque)
- Making a sharp turn
- Passing over roughened surface
Turbulent flow creates eddy currents, where the blood flows with much greater resistance due to added
friction
Reynold’s number
is the tendency for turbulence to occur
Re = (v x d x p)/n
Reynold’s number is ______ proportional to the velocity of blood flow, the diameter of the vessel and the density of the blood
directly
Reynold’s number is _____ proportional to the viscosity of the blood
inversely
Poiseuille’s Law states that the VOLUME of a liquid flowing through a vessel is _____ proportional to the pressure of the liquid, _____ proportional to the 4th power of the radius of the vessel, and ______ proportional to the viscosity of the liquid and length of vessel.
directly; directly; inversely
About ____ of the total SVR to blood flow is arteriole resistance in the small arterioles
2/3
SVR is MAP/CO however, it cannot
be measured
SVR is the _____ to blood flow in a vessel
impediment
Conductance is the reciprocal of ______
resistance
Conductance is the measure of the blood flow through a vessel for a given ______ difference
pressure
Hematocrit
proportion of blood that is red blood cells (rbc)
Who has more hematocrit?
Men (42%) vs. Women (38%)
What are 3 examples of hematocrit alterations?
- Anemia (lowered n = increased C)
- Activity Levels (elite athletes) - (increased O2 demand)
- Altitude (significant increase in hematocrit during 1st 72 hours of change in elevation)
If you _____ hematocrit, you will markedly ____ blood viscosity.
increase; increase
Hematocrit equation (pouiseuille)
F = n x change in P x r^4 / 8 x n x l
Blood Flow Autoregulation say that:
- if n increases, the c will ____
- during sympathetic inhibition, there is 2x flow and vaso_____
- During sympathetic stimulation, the blood flow is tightened up and vaso_____
- A decrease in pressure = ____ in resistance
- if n increases, then c will decrease
- during sympathetic inhibition, 2x flow and vasodilation
- during sympathetic stimulation, tightened up and vasoconstriction
- decrease in pressure = decrease in resistance
Take homes of Circulation (4)
- The majority of blood is distributed among ____ circulation with majority within _____ system
- Rate of blood flow in controlled by __________
- ____ of the vessel is the most important factor in determining the flow of blood
- About 2/3 of the total SVR to blood flow is arteriole resistance in the _______
- systemic; venous
- needs of the tissues
- Radius
- small arterioles
