Cardio equations

Question 1

Whole cell current

Answer 1

I = N.i.Popen 
(I = whole cell current; N = number of channels; i = single channel current; Popen = open probability of channels)

Question 2

Flow with regards to current and time

Answer 2

Q = I.t
(Q = flow; I = whole cell current; t = time)

Question 3

Flow with regards to resistance

Answer 3

Q = (P1 - P2)/R 
(Q = flow; P = pressure; R = resistance)

Question 4

Total resistance in series

Answer 4

Rt = R1 + R2 + R3 … + Rn

Question 5

Total resistance in parallel

Answer 5

1/Rt = 1/R1 + 1/R2 + … + 1/Rn

Question 6

Poiseuille’s law flow

Answer 6

Q = (π(P1 - P2)r^4)/(8ηL)
(Q = flow; P = pressure; r = radius; η = viscosity of the liquid)

Question 7

Poiseuille’s law resistance

Answer 7

R = (8ηL)/(πr^4)
(R = resistance; η = viscosity of the liquid; r = radius)

Question 8

Total mechanical energy per unit volume

Answer 8

= P + ρgh + 1/2ρv^2

P = pressure; ρ = density; g = gravity; h = height; v = velocity

Question 9

Pressure energy

Answer 9

= V.P

V = volume; P = pressure

Question 10

Potential energy due to gravity

Answer 10

= V.ρgh

V = volume; ρ = density; g = gravity; h = height

Question 11

Kinetic energy

Answer 11

= V.ρv^2/2

V = volume; ρ = density; v = velocity

Question 12

Intracellular and exctracellular concentrations:
Sodium
Potassium
Chloride
Calcium

Answer 12

Sodium: IC = 15mM EC = 150mM
Potassium: IC = 150mM EC = 5.5mM
Chloride: IC = 9mM EC = 125mM
Calcium: EC = 1-2nM IC = 100mM

Question 13

Reversal potentials:
Sodium
Potassium
Chloride
Calcium

Answer 13

Sodium: 45mV
Potassium: -90mV
Chloride: -90mV in neurons, -30mV in smooth muscle
Calcium: 134mV