Cardio physiology equations Flashcards Preview

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Flashcards in Cardio physiology equations Deck (12):
1

What determines blood flow velocity?

V = Q/A

V = velocity (cm/sec)
Q = Flow rate (mL/sec)
A = Area (cm^2)

2

What is the equation for blood flow?

Q = Pressure difference/ Resistence

Q = blood flow.

3

What determines the resistance to blood flow in a vessel (Poiseuille equation)?

R = 8nl/(pi)r^4

R = resistance
n = viscosity
l = length of vessel
r^4 = radius to the 4th power

4

What is the significance of Reynold's number?

Reynold's number (Nr) predicts whether blood flow will be turbulent or laminar. Nr less than 2000 will be laminar flow, Nr greater than 2000 is likely turbulent, and Nr greater than 3000 is always turbulent.

5

What is the equation for Reynold's number?

Nr = pdv/n

Nr = Reynold's number
p = density of blood
d = diameter of vessel
v = velocity of blood
n = viscosity of blood

6

What is the equation for the capcitance or compliance of a vessel?

C = V/P

C = capacitance or compliance
V = volume
P = pressure

7

How is stroke volume determined?

SV = EDV - ESV

SV = stroke volume
EDV = end diastolic volume
ESV = end systolic volume

8

How is the ejection fraction determined?

Ej fraction = SV/EDV

SV = stroke volume
EDV = end diastolic volume

9

What is the law of Laplace?

P = 2HT/r

P = pressure
H = thickness
T = tension
r = radius

10

What is the relationship between tension pressure and radius?

T = P x r

T = tension
P = pressure
r = radius

11

How is cardiac output determined?

CO = HR x TPR

CO = Cardiac output
HR = heart rate
TPR = total peripheral resistance

12

What determines mean arterial pressure?

MAP = CO x TPR

MAP = mean arterial pressure
CO = Cardiac output
TPR = total peripheral resistance