Equations

Question 1

Time of diffusion

Answer 1

X^2/2D

D is typically 10^-5 cm2/s

Question 2

V=

Answer 2

IR

Question 3

C=

Answer 3

Q/V

Question 4

Nernst equation

Answer 4

E= RT/Fz x ln([ref]/[test])

Question 5

Nernst at 20 degrees

Answer 5

E(mV)= 58/z * log([out]/[in])

Question 6

Give GHK equation

How is it different at 20 degrees C

Answer 6

E=RT/F * ln(P[K]o + P[Na]o +P[Cl]i / P[K]i +P[Na]i + P[Cl]o)

58log instead of RT/F*ln

Question 7

Vt=

Answer 7

VT(1-e^-t/τ)

Question 8

τ=

Answer 8

RmCm

Question 9

λ=?

Answer 9

✔️ (Rm/Ri)

Question 10

I(ion)=?

Answer 10

g (ion) x (V(ion) - E (ion))

Question 11

Give velocity equation for myelinated fibres

For unmyelinated fibres?

Answer 11

v α diameter

v α ✔️(diameter)

Question 12

Give Darcy’s Law

Answer 12

Q=P/R

Question 13

Give Poiseuille’s law

Answer 13

R= Lη/(r^4)

Question 14

MAP=

Answer 14

D+(S-D)/3

Or

(2D + S)/ 3

Question 15

CO=?

3

Answer 15

SV x HR

(ABP-RAP)/TPR

(ABP-MSFP)/TPR

Question 16

VR=

Answer 16

(MSTP-RAP)/RvR

Question 17

Give Fick’s Law

Answer 17

Qx = (AcPx([X]c-[X]if)

Question 18

Give Fick’s principle

Answer 18

CO= (rate of CO2 loss)/ (venous CO2 - arterial CO2)

Question 19

Give the perfect gas equation

Answer 19

PV= nRT

Question 20

Give the perfect gas equation if moles and R are kept constant

Answer 20

P1V1/T1 = P2V2/T2

Question 21

Va=

2

Answer 21

(Vt-Vd) x f

V(ECO2) / P(ACO2) * K

Question 22

Alveolar gas equation

Answer 22

P(AO2)= P(IO2)-P(ACO2) [FIO2 + (1-FIO2)/R]

Question 23

Equation relating pressure and surface tension

Answer 23

Pressure= 2x Surface Tension/ r

Question 24

R=?

In resp (using π)

Answer 24

8nl/πr^4

Question 25

Forced expiration ratio=?

Answer 25

FEV1/FEV

Question 26

Net flux=?

Answer 26

ΔP x s x (area/thickness) x D

Question 27

diffusion coefficient=

Answer 27

s/✔️Mr

Question 28

[Blood O2]=

Answer 28

(1.39x[Hb]x %sat) + (0.003xPO2)

Question 29

pH=

2

Answer 29

pKa+ log([HCO3-]/0.03CO2)

-log[H+]