Week # 8 Diffusion, Mixtures & Solutions Flashcards
Fick Rules!
What is a permeable membrane?
a thin membrane of material through which either liquid or gas molecules will pass
(not specific)
What is a semi-permeable membrane?
is a membrane that will allow certain molecules or ions to pass through it by diffusion
(specific or selectively permeable)
What is diffusion?
Diffusion is the movement of solute molecules from an area of greater solute concentration to an area of lesser solute concentration
Where does the energy to drive diffusion come from?
entropy
this is the process of net movement of one type of molecule through space as a result of random motion
What is osmosis?
Net movement of solvent is from the less concentrated to the more concentrated solution, which tends to reduce the difference in concentrations
What is osmotic pressure?
the potential drive for the concentration of water to equalize.
(or the push from fluid)
What is oncotic pressure?
the overall osmotic effect of colloids
or the pull from proteins
What are the 4 primary forces that determine fluid movement through the capillary membrane?
- capillary pressure (osmotic water push)
- interstitial fluid pressure (osmotic water push)
- plasma colloid pressure (protein pull)
- interstitial fluid colloid pressure (protein pull)
What are the 3 requirements for osmosis to occur?
- pressure gradient (high to low)
- semipermeable membrane to water only
- time
What is an osmole?
The standard unit of osmotic pressure based on one molar concentration of an ion in a solution
What is osmolality?
The number of moles of solute per kilogram of solvent
What is osmolarity?
The number of moles of solute per litre of solution
What is the normal plasma oncotic pressure?
- 25 mmHg
What is the normal plasma osmolality?
280 - 290 mOsm/L
Fick’s Law of gas diffusion describes what?
the rate of diffusion across a membrane
What 3 things are directly proportional to diffusion in Fick’s gas equation?
- concentration gradient
- membrane surface area
- solubility of gas in membrane
Which two things are inversely proportional to diffusion in Fick’s gas equation?
- membrane thickness
2. square root of the molecular weight
the bigger it is, the slower it’ll diffuse
What 3 factors are important for non-gas diffusion?
- gradient (concentration and electrochemical)
- lipid solubility
- size
What does Graham’s Law state?
that the rate of effusion, or the movement of gas through a small opening, is inversely proportional to the square root of the molecular mass
(or, the bigger it is, the slower the gas will move through small openings)
Based on Graham’s Law, which gas will diffuse/effuse faster: helium or oxygen?
helium, because it is smaller
Who’s law explains diffusion hypoxia?
Fick’s Law, cause he’s bad ass.
you would think it would be Graham, but his law is basically a piece of Fick’s Law.
A colloid consists of _____ + ______.
liquid and liquid (propofol)
When you increase the temperature of a gas, will the solubility of that gas increase or decrease?
decrease
a hypothermic patient will be slower to wake up since the anesthetic gas is more soluble
When you increase the temperature of a liquid, will the solubility of that liquid increase or decrease?
increase
What is Henry’s Law?
by increasing the gas above a liquid, more gas will be in the liquid
(giving 100% oxygen will increase PaO2)
What is the Ostwald coefficient?
The quantity of solvent needed to dissolve a quantity of gas at a given temperature and pressure
(gas/liquid NOT corrected)
What is the Bunsen coefficient?
the amount of gas in a liquid at 273.15 Kelvin and 101.3 pKa
gas/liquid CORRECTED
What is partition coefficient?
the ratio of concentrations of a compound in a mixture of two immiscible phases at equilibrium
(two phases at a given temp)
How many micrograms per milliliter is 1:200,000 epinephrine?
5mcg/mL
How many micrograms per milliliter is 1:100,000 epinephrine?
10mcg/mL
How many micrograms per milliliter is 1:1,000 epinephrine?
1000mcg/mL (or 1mg/mL)
How many milligrams per milliliter do you get with a 1% solution?
10mg/mL
How many milligrams per milliliter do you get with a 2% solution?
20mg/mL
How many milligrams per milliliter do you get with a 0.1% solution?
1mg/mL
