Lecture 11/4: CV Biophysics Overview Pt 1 Flashcards
Final
What organ is a major part of the circulatory system?
Kidneys
CVS =
Cardiovascular system
What are the 3 major functions of the circulatory system?
- Transporting nutrients to tissues
- transporting waster products away from tissues
- Circulating hormones released from the endocrine system into the CVS
Describe units: Volume
A size
Ex) L, ml, gallon
Describe units: Velocity
distance/time
Ex) miles/hr
Describe units: Pressure
Force
Ex) mmHg or cmH2O
Describe units: Area
Also a size
Ex) cross-sectional
Describe units: Blood Flow
Volume/time
Ex) ml/min or dL/min
What factors influence blood flow?
-Vascular resistance (or vascular conductance)
-Blood pressure
__________ determines what type of pressure we have
Vascular resistance
What is another name for a point in the aorta where vascular resistance is created?
choke point
What happens when vascular resistance in the aorta is increased: Blood flow; pressure before choke point; pressure after?
Blood flow: decreased
Pressure before: increased
Pressure after: decreased
What happens to blood flow when you decrease vascular resistance?
increase
What drives blood flow? Give an example. What alters blood pressure?
Blood pressure
Ex) brain using CPP to drive brain blood flow
vascular resistance
How is vascular conductance and vascular resistance similar?
Conductance is the inverse of resistance
-How easy it is to get blood through a vessel
Ex) High vascular resistance = means blood is hard to get through vessel = low vascular conductance
High resistance = low conductance
low resistance = high conductance
What is Poiseuille’s Law?
Determines blood flow by taking a better look at vascular resistance
Factors in physics: viscosity, density, etc
States that a small change in blood vessel diameter has a large change on blood flow
Ex) Blood vessel relaxes a little bit –> huge increase in blood flow
What are 2 basic but major functions of the kidney?
- managaing fluid volume
- filtering
______ take blood to the heart and ______ take blood away from the heart
veins
arteries
What organ manages fluid volume in the body?
kidney
Increasing fluid volume in the kidneys _______ blood volume in the CVS
increases
What are the higher pressure blood vessels?
Arteries
Where is the majority of blood stored in the body? how much?
Systemic veins
84%
Differentiate between a system in series & a system in parallel
System in series: blood vessels connected side by side
-The resistance is now combined
-Resistance increases the more blood vessels combined
R(total) = R1 + R2 + R3….
System in parallel: Blood vessels connects on top of each other
-resistance in now split between the vessels (decreased) & blood flow decreased
**R(total) - 1/R1 + 1/R2 + 1/R3….
x-section =
cross sectional area
what is x-section exactly?
if the blood vessel is a cylinder
xsection is the area of the circle in the cylinder
How many aortas and venae cavas do you have?
aorta = 1
venae cava = 2 (superior & inferior)
Name the blood vessels in order leaving your heart and returning to your heart
Aorta
Large arteries
Small arteries
Arterioles
Capillaries
Venules/Veins
Small veins
Venae Cavae
What happens to xsection when you get closer to the heart? What does this mean?
xsection decreases
Velocity increases
Xsection is low dt there only being 1/2 vessels, its a bigger large vessel so velocity is high
What is the xsection of the aorta? describe this
2.5 cm2
xsection is large but there is only 1; velocity high.
What is the xsection of capillaries? describe this
2500 cm2
The xsection is actually very small but there are so many capillaries so thats why this is the highest area
Velocity low through here bc xsection high
What is the xsection of the venae cava? describe this
8 cm2
xsection is large but there is only 2 of them, so low; but velocity high.
The L artrium has a very _____ pressure
low
The L ventricle, aorta, & large arteries has a ______ pressure
high
At what blood vessel does BP start to taper?
Small arteries
What are your high resistance vessels or “choke points”? What does this mean?
Small arteries
arterioles
These vessels are able to contract and relax
What is proximal to the small arteries?
Large arteries
What is distal to the arterioles?
Capillaries
What is normal BP in the veins and R atrium?
10 mmHg
Describe blood flow once you pass the capillaries
Only drops a little bit bc veins dont have much resistance dt thin walls (increased compliance)
Veins have _______ compliance dt thin wall
increased
What happens when blood moves through the small arteries and arterioles? Why?
BP drops
These are the high resistance vessels
When we take BP from cuff, it’s looking at BP in the ___________
Large arteries
How does phenylephrine work? what is an AE that we need to be looking for with this?
Squeezes on the small arteries and arterioles to increase pressure in the large arteries
Pressure in the capillaries/veins will be low tho —-> decreased perfusion to the peripheries!!!!! Necrosis
What would happen if all blood vessels were completely open? (No resistance)
We would have no blood pressure –> pressure drives flow –> we would have no blood flow
What blood vessel does all blood have to flow through?
Aorta
Beside vascular resistance, what a secondary reason thats BP decreases as it leaves the heart?
increasing xsection (systems in parallel) –> decreases velocity and resistance which contributes to decreasing pressure.
What is the Circulatory Function Theory?
Blood flow is determined by metabolic rate of the tissues.
Kidneys sense this and attempt to make up the fluid volume to increase/decrease blood volume by holding on to/excreted ions.
Ex) high metabolic rate = needing to increase blood flow –> need to increase blood volume –> need to increase fluid volume –> kidney senses this –> holds on to more ions to hold on to more fluid to put into CVS
What is orderly & efficient blood flow called?
Laminar flow
Describe Laminar Flow
Orderly and efficient blood flow through a vessel
-Edges of the vessel has a slower blood flow dt high resistance walls
-The center of the vessel has fastest blood flow bc its farther away from high resistance walls
Describe Disorderly Flow
“Turbulent Flow”
Not efficient & causes problems
Cause: anything that causes a narrow opening “choke point” of the blood vessel –> velocity after would be high –> squirting blood against vessel walls
-behind&after choke point: Ca++ & cholesterol in blood getting slammed or squirted against vessel wall & getting stuck there –> arteriosclerosis/calcification
What is the equation called to predict turbulent flow?
Renold’s equation
Re = (v . d . p) / n
Do not memorize this equation
Will use next semester
I only put this here incase he uses it for extra credit
Kidney’s get about ____% of minute cardiac output. Which is about how much?
22%
1.1 L/min
How many ml and dL is 1.1 L?
ml = 1100
dL = 11
Why do kidneys get more blood flow than they actually need?
To be an effective filter
kidney perfusion not determined by current metabolic rate
Just incase they need to start filtering way more than usual; they have the blood flow to increase their metabolic rate to do do.
How do we PHYSICALLY measure blood flow?
ultrasonic probe around blood vessel
What is Ohm’s law in relation to Pressure?
△Pressure = Flow x Vascular resistance
△P = P1 - P2
Large difference = lots of flow
Small difference = less flow
As vascular resistance increases, flow______
decreases
As △Pressure increases, flow ________
increases
Equation: Poiseuille’s Law Dont memorize
F = (π∆Pr4)/8nl
Next semester
What is the BP in the abdominal aorta?
100mmHg
What is normal cardiac output?
5 L
What is normal renal blood flow?
22% of cardiac output
Cardiac output is 5 L
5 x 0.22 = 1.1
RBF = 1.1 L/min
The _______ takes blood into the kidney & the ______ takes blood out of the kidney and back into the CVS
renal artery
renal vein
Equation: Vascular Conductance
Conductance = 1 / Resistance
