S1M3 Cardiac Physiology: Hemodynamics

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)

7mmHg

25/0 mmHg

120/0 mmHg

-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!)

If they have any deviations from the normal pressures of the chambers!

contracts! duh.

relaxes! comon! what is this grade school?

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.

• 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 pressure = increase Flow
• Increase resistence = decrease flow

The MAP (mean arterial pressure)

Mean Pulmonary Artery Pressure -- Left Atrial Pressure

The right venticle!

• opposes
• It is dependent upon the physical properties of vessels and blood

• 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

• 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

The radius, r --SANS has sec by sec control of the radius of our vessels

• Incr P = Incr FLOW
• Incr r⁴ = Incr FLOW (double r, 16 fold increase in FLOW)
• Incr L = DECREASE FLOW*
• Incr Viscosity (n) = DECREASE FLOW*

*inversely related to flow

RADIUS.

• because in the Poiseuille-Hagan Equation
• r⁴ will increase or decrease the flow by 16 fold.

The number of L per min that are flowing out of the heart

the ARTERIOLES (the ones we contract)

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)

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.

• 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.
• 

• The turbulent flow of our heart valves, which is normal.
• 

ADD the TOTAL resistence of each, EASY

R_tot = R₁ + R₂ + R₃ + R₄ + R₅

R = 1/ 1/R₁ + 1/R₂ +1/ R₃

P = F x R

• F= Flow
• R=Resistance

*Remember when in a tube, must always subtract the pressure you calculate from the original pressure in the begining of the tube!!!

• LOWER! Use this rule to check your math, total resistance should always be lower than a single resistance.
• 

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 = low compliance

• Arteries want to snap back!
• They are the waterbaloons---they fill with blood and as a result want to snap back

• the physical property of a vessel (a type of vascular compliance = stretchiness!)
• determined by amt. of CT present (changes with age and disease)

is the change in vascular tone due to smooth muscle contraction (altered second to second)

• A vein!
• Veins act as "resevoirs"because they are 25% more compliant than your arteries
• This "resevoir" increases CO
• *Remember CO = MAP x TPR

capacitance vessels are veins remember**

• 1) Smooth Muscle surrounding veins is innverv by SANS
• 2) This stimulates contraction
• 3) 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!!!

Static!


It keeps blood moving during ventricular diastole (relaxation)

To KEEP BLOOD MOVING during ventricular diastole

Normally around 100

MAP is the average arterial pressure during a single cardiac cycle

Pulse pressure is the difference between the systolic (relax) and diastolic (contraction) pressures


Pulse Pressure = P_sys - P_dias