Molar concentration, amount concentration or substance concentration. Based on specific volume of the solution.
A measure of the concentration of a solute in a solution in terms of amount of substance in a specified amount of mass of the solvent. Moles solute / mass of solvent.
What is the normal serum osmolality?
282 - 303 mOsm/kg
Which is isosmotic with a cell?
a) 100 mM glucose solution
b) 100 mM sodium chloride solution
c) 100 mM calcium chloride solution
100 mM calcium chloride solution
300 mOsm (blood plasma is same)
What is the osmolarity of a 100 mM glucose solution?
What is the osmolarity of a 100 mM sodium chloride solution?
100 from Na+ and 100 from Cl-
What is the osmolarity of a 100 mM calcium chloride solution?
100 from Ca
200 from Cl2 (100 x 2)
What is the osmolarity of blood?
Osmolarity is related to the number of molecules in a solution?
How many milliosmoles in Glucose (formula weight 180.0)?
Formula weight = 180
18.0 g glucose/L = 100 mM glucose = 100 mOsm
How many milliosmoles in NaCl (formula weight 58.5)?
Formula weight 58.5 = 5.85 g NaCl/L = 100 mM NaCl
100 mEq/L Na+ and 100 mEq/L Cl- = 200 mOsm total
What does vant Hoff's Law refer to?
Osmotic pressure = RTnc
R = ideal gas constant
T = absolute temp (K)
n = # of particles formed by dissociation of a solute molecule
c = molar concentration of solute
What is the formula for Effective osmotic pressure?
πeff = σRTnc
σ = membrane permeability coefficient (0 = completely permeable, zero osmotic pressure because zero times anything = zero; 1 = impermeable)
What type of membrane do you need for osmotic pressure?
A semi-permeable membrane. You have to take into account how permeable the membrane is.
What is equilibrium potential?
Where the electrochemical forces acting on an individual ion balance out and the number of ions entering the cell equals the number exiting the cell
Na+ = +60 mV
K+ = -90 mV
Cl- = -70 mV
What is the Nernst Equation and what does it describe?
It describes the relationship of the equilibrium potential of an ion and the ion concentration gradient.
Eion = RT/ZF x ln([ion]0 / [ion]1)
R = gas constant
T = temp
Z = valence
F = Faraday's constant
What does the Hodgink-Katz-Goldman Equation describe?
the relationship of the membrane potential, the permeability of ions through the membrane, and the ion concentration gradients
What is the resting membrane potential of a cardiac myocyte?
What can diffuse through membranes?
Small, non-polar molecules/drugs (lipid soluble)
What cannot diffuse through a membrane?
Polar (ionized, water soluble) molecules/drugs cannot diffuse through membranes unless there is a carrier
The amount of ionized drug is affected by?
The pKa of a drug is the pH at which?
50% is ionized