OS2 Equations

Question 1

Nernst potential

Answer 1

61 log [outside cell] / [ inside cell]

Question 2

2 equations for MAP

Answer 2

1. SVR x CO

2. Diastolic + 1/3 pulse pressure

Question 3

2 equations for pulse pressure

Answer 3

1. Systolic pressure - diastolic pressure

2. Stroke volume / aortic compliance

Question 4

Cardiac output (2 equations)

Answer 4

1. stroke volume x heart rate

2. O2 consumption / (O2 pulmonary vein - O2 pulmonary artery)

Question 5

relationship of length and radius to resistance

Answer 5

increase length, increase resistance; increase radius, decrease resistance

ηL/r^4

Question 6

SVR

Answer 6

MAP-RAP / (CO x 80)

flow = P/R
R = P/flow

sometimes right atrial pressure is ignored since very small and hard to measure

Question 7

tension + stress

Answer 7

tension = length x radius
stress = (length x radius) / thickness

Question 8

Flow (Q)

Answer 8

delta P / resistance

pressure = resistance x flow

Question 9

Diffusion flow (J)
how it's affected by:
-thickness
-area
-concentration difference

Answer 9

[D x A (C1-C2)] / X

X= thickness 
D= diffusion coefficient
A= area
C1-C2 = concentration difference

Question 10

Velocity of fluid flow

Answer 10

V = flow / area

Question 11

Starling’s Law Equation for flow Q

Answer 11

Q = K [(Pc-Pi) – σ (πc –πi)]

K = filtration coefficient

Question 12

Stroke work

Answer 12

Stroke volume x Mean arterial Pressure

Question 13

Stroke volume

Answer 13

End diastolic volume - end systolic volume

Question 14

Cardiac Efficiency

Answer 14

external work / internal work

Question 15

internal work is a function of what type of factors?

Answer 15

laplace law (Regading tension)

• thickness
• radius (dilated ventricle)
• increase in pressure

increased tension –> increased internal work –> decreased cardiac efficiency

Question 16

2 Equations for compliance

Answer 16

1. dV/dP (measure of pressure change for a given change volume
2. stroke volume / pulse pressure (PP = SV/compliance)

Question 17

Inverse of compliance

Answer 17

stiffness

Question 18

Ejection Fraction

Answer 18

Stroke volume / End diastolic volume

Question 19

Clearance rate

Answer 19

(Ux * V) / Px

Question 20

Filtered Load

Answer 20

GFR * Px

Question 21

Excretion rate

Answer 21

Ux * V = FLx + S - R

Question 22

Fractional Excretion

Answer 22

(Ux*V) / FLx

Question 23

Filtration Fraction

Answer 23

GFR / RPF

Question 24

Anion Gap

Answer 24

[Na] - [Cl] - [HCO3]

Question 25

Net Acid Excretion

Answer 25

[U(NH4)*V] + [U(TA)*V] - [U(HCO3)*V]

Question 26

Posm

Answer 26

2P(Na) + Urea/2.8 + Glucose/18

Question 27

Volume excreted

Answer 27

mosm excreted / Urinary osm (mosm/L)

Question 28

Oxygen dissolved in plasma

Answer 28

0.003(PO2)

Question 29

O2 carrying capacity of Hb

Answer 29

1.34 ml O2

Question 30

hemoglobin capacity of O2

Answer 30

[Hb] x carrying capacity | normal values: 15 g Hb/dl blood x 1.34 mlO2/gHb

Question 31

O2 content

Answer 31

O2 saturation x O2 carrying capacity + amount dissolved (Hbsatuation x 1.34 x [Hb]) + .003PaO2 when PaO2 = 100, SaO2 = 98%

Question 32

relationship between oxygen capacity (O2 bound to hemoglobin) and PO2

Answer 32

nonlinear

Question 33

Respiratory Quotient (RQ)

Answer 33

CO2 production/O2 consumption

Question 34

Minute Ventilation (VE)

Answer 34

Tidal Volume x respiratory rate

Question 35

Alveolar Ventilation (VA)

Answer 35

(Tidal Volume - Dead Space) x respiratory rate

Question 36

FEV1 (forced expiatory volume of air expired in first second) is normally 75-80%, which is expressed as:

Answer 36

FEV1 / FVC FVC = forced vital capacity

Question 37

Alveolar Gas Equation | PAO2

Answer 37

PaO2 = PIO2 - (PACO2/RQ)

Question 38

PIO2

Answer 38

FIO2(760-47mmHg) 760=Patm 47=Ph20 FIO2 = concentration of O2 (usually 21%

Question 39

pCO2

Answer 39

(.863xCO2 produced) / Alveolar ventilation recall: VA= (TV-DS)xRR take away point: pCO2 decreases as alveolar ventilation increases

Question 40

Recall that Fick's law of Diffusion = [D x A (C1-C2)] / X What is D (diffusion capacity) proportional to?

Answer 40

D proportional to solubility / square root (MW) smaller MW has higher diffusion rate, and higher solubility has higher diffusion rate

Question 41

Pulmonary vein [O2] is measured in _______ Pulmonary artery [O2] is measured in ______

Answer 41

peripheral artery systemic mixed venous blood

Question 42

Coronary perfusion pressure (pushing into heart to give O2--only occurs during diastole)

Answer 42

Aortic diastolic pressure - pressure drop across stenosis - LVEDP

Question 43

Dead space

Answer 43

VD = VT x (PACO2-PECO2)/PACO2 where PECO2 is PCO2 of expired air

Question 44

pCO2

Answer 44

CO2 produced / (TV-DS)rr

Question 45

Tension | Stress

Answer 45

``` Tension = Pr Stress = Pr/2h ```

Question 46

Oxygen uptake (2)

Answer 46

1. Flow x (CaO2-CvO2) where CvO2= mixed venous O2 content 2. (Hbx1.34)(SaO2-SvO2) x CO