S1M3 Cardiac Physiology: Hemodynamics
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KNOW THESE NORMAL PRESSURES:
DRIVING PRESSURE (systemic circulation) = ?
MAP (Mean Arterial Pressure) which is the average of 120/80, or 100 mmHg
Why not RAP
(Right Atrial Pressure)? Because it's nearly ZERO (look at RA in picture below)
Normal pressure in the LEFT ATRIUM?
Normal pressure in the RIGHT VENTRICLE?
Normal pressure in the LEFT VENTRICLE?
Normal pressure in the RIGHT ATRIUM?
-4 to 4 mmHg (it's returning deoxy blood from venous network of systemic circulation...comon!! it has to be at such a low pressure!)
What's one of the essential, easiest way to see if a patient has a heart problem?
If they have any deviations
from the normal pressures of the chambers!
Systolic pressure is the pressure when the heart _________?
Diastolic pressure is the pressure when the heart _________?
relaxes! comon! what is this grade school?
Bulk flow says what?
That Blood Flow (F) = Difference in Pressure (P1-P2) over Resistance (R)
Pressure is our driving force, so it needs to be larger than our resistance to get flow.
Systole occurs when? Be SPECIFIC!
- When the ventricular muscles are contracting, generating a circumferential tension in the ventrical walls, increasing pressure in the chamber.When ventricular pressure exceeds the pressure in the pulmonary artery (right pump) or aorta (left pump) blood is forced out of the chamber via the outlet valve.
Increase in pressure?
Increase in resistence?
- Increase pressure = increase Flow
- Increase resistence = decrease flow
Systemic Circulation Driving Pressure is = ?
The MAP (mean arterial pressure)
Pulmonary Circulation Driving Pressure = ?
Mean Pulmonary Artery Pressure -- Left Atrial Pressure
Pulmonary artery leave what ventricle?
Resistance is a force that _________ flow.
- It is dependent upon the physical properties of vessels and blood
What are the three factors that affect resistence (R) that opposes blood flow?
- Viscosity of the blood (n)
- Length of the vessel (L)
- Radius of the vessel (r) *** r is most imporant! it is inversely related to resistence--- the more you increase the radius of the BV the LOWER the Resistence will be because it's r4
Which factor that affects the resistence of blood flow is most important?
- r4 = radius!
- very powerful, it is inversely related to the resistence, so if you increase the radius of a blood vessel you decrease the resistence
Our SANS has second to second control of which of these components that affect resistence?
The radius, r --SANS has sec by sec control of the radius of our vessels
Increase in Pressure? = Flow?
Increase in Radius? = Flow?
Increase in Length? = Flow?
Increase in Viscosity (n)? =Flow?
*inversely related to flow
- Incr P = Incr FLOW
- Incr r4 = Incr FLOW (double r, 16 fold increase in FLOW)
- Incr L = DECREASE FLOW*
- Incr Viscosity (n) = DECREASE FLOW*
What is the most powerful indicator of flow?
- because in the Poiseuille-Hagan Equation
- r4 will increase or decrease the flow by 16 fold.
What is cardiac output (CO)?
The number of L per min that are flowing out of the heart
Most of your Total Peripheral Resistence (TPR) is from what vessels?
the ARTERIOLES (the ones we contract)
What is the most important equation of this ENTIRE BLOCK?
where your Mean Arterial Pressure (MAP)
is equal to your Cardiac Output (CO
, the number of L/min flowing out of heart) times your total peripheral resistence (TPR)
Your MAP is =
MAP is your blood pressure
AORTIC PRESSURE, which because your RAP (right atrial pressure) is basically zero, the driving pressure of your systemic circulation
is your MAP.
If Alberto Contador is blood doping, what negative effect could this have on his Blood Flow (F)?
- Break out the Poiseulle-Hagan Equation!
- He would increase the viscosity or n of the blood, and according to Poise's equation, viscosity is inversely related to the flow, so there would be a decrease the blood flow F. And he could have a heart attack and Lance would win naturally.
When we listen for heart sounds (auscultate)what are we listening to?
- The turbulent flow of our heart valves, which is normal.
How do you determine the resistence of vessels in series?
ADD the TOTAL resistence of each, EASY
Rtot = R1 + R2 + R3 + R4 + R5
How do you determine the resistence of vessels in parallel?
R = 1/ 1/R1 + 1/R2 +1/ R3
EQ for Pressure at a specific point?
P = F x R
*Remember when in a tube, must always subtract the pressure you calculate from the original pressure in the begining of the tube!!!
The total resistence of a parallel system of vessels is always ______ than the resistance in a single vessel
- LOWER! Use this rule to check your math, total resistance should always be lower than a single resistance.
Veins have a very high ______ which allows them to exhibit relatively large changes in blood volume, but smaller changes in pressure
VEINS = HIGH COMPLIANCE
- Veins are able to stetch (compliance) to high volumes and not exhibit a lot of pressure---so they don't have a high recoil force like arteries do
- Think of veins as your ZIP-LOCK baggies holding water, they hold a lot of blood but they don't exhibit and huge recoil force
Arteries have a low ___________ which causes them to exhibit small changes in blood volume for a given pressure.
Arteries = low compliance
- Arteries want to snap back!
- They are the waterbaloons---they fill with blood and as a result want to snap back
Static compliance is __________?
- the physical property of a vessel (a type of vascular compliance = stretchiness!)
- determined by amt. of CT present (changes with age and disease)
Dynamic compliance is __________?
is the change in vascular tone due to smooth muscle contraction (altered second to second)
Step 1 Related: What is a capacitance vessel?
- A vein!Veins act as "resevoirs"because they are 25% more compliant than your arteries
- This "resevoir" increases CO
- *Remember CO = MAP x TPR
How do capacitance vessels increase CO?
capacitance vessels are veins remember**
- 1) Smooth Muscle surrounding veins is innverv by SANS
- 2) This stimulates contraction3) Causes a decrease in venous compliance
- 4 )Vol. of bllod the veins can hold is reduced, displacing excess blood towards the heart! movin' it along!
- 5) Cardiac Output as a result is increased!!!
The "Windkessel Effect" is a component of ______ compliance
It keeps blood moving during ventricular diastole (relaxation)
What is the purpose of the Windkessel Effect?
To KEEP BLOOD MOVING
during ventricular diastole
MAP = ?
Normally around 100
MAP is the average arterial pressure during a single cardiac cycle
Pulse pressure = ?
Pulse pressure is the difference between the systolic (relax) and diastolic (contraction) pressures
Pulse Pressure = Psys - Pdias
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