Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
week one lecture2bio
Diffusion and Osmosis
| Term | Definition |
|---|---|
| passive diffusuin | - through lipid -aqua pore aquaporins lipid soluble molecules |
| aqueous diffusion | - via channels -doesn't require energy - requires concentration gradient -tranverses the plasma membrane |
| facilitated diffusion | - via specialised carrier proteins. - binds to the drug from one side and to the membrane from the other side. then change conformation and release the other side. - doesnt require energy - requires concentration gradient. |
| active transport | - via specialised carrier proteins. - requires energy - can move molecules against their concentration gradient. |
| endocytosis (pinocytosis) | - invagination of a part of the membrane. - the molecule is encased in a small vesicle then released inside the cell. |
| ICF | -high in K+ - low in NA+ _low in Cl- |
| ECF (plasma) | - high in Na+ -low in K+ -high in Cl- - |
| how does cell maintain relatively a high K+ concentration. | not by making its membrane totally impermeable to these ions but by using the Na-K pump to extrude Na+ actively from the cell and to transport K+ actively into the cell. |
| simple diffusion | - random movement of solute molecules in solvent tending towards an equilibrium - |
| - solute movements (distribution) | - solutes tend to distribute themselves by diffusion uniformly and independently of each other. |
| Diffusion | - net moments from an area great concentration to an area lesser concentration -depends on the permeability of solute - concentration gradient across the membrane barrier -membrane permeability to the solute. |
| - rate of diffusion | - differes from: -physiological property of the solute and the solvent - temperature electric field |
| permeability | -The permeability of the drug effects what tissues in the body it will affect - each tissue has a diff permeability This is how specific drugs target specific areas /organs etc. |
| cross sectional area | the area available for the diffusion in the membrane. |
| electrochemical gradient | - the driving force that determines the passive force of a solute across the membrane. - it is also effected by the concentration gradient. |
| The concentration gradient and the voltage difference across the membrane | -are the two determinants of the electrochemical potential energy difference for X between the two compartment |
| concentration gradient | -is a measure of the relative difference in concentration across the membrane |
| flow | = energy gradienr/resistance. |
| Stokes’ law | a perfect sphere traveling through a viscous liquid feels a drag force proportional to the frictional coefficient |
| Permeability = diffusion and partitioning | P = Kp . D / x kp is lipid-water partition coefficient which is concentration in the lipid devided by the concentration in t he blulk aqueous phase. D is the diffusion coefficient in cm^2/s |
| Fick Equation | J1 2 = D x A (S1 – S2)/x |
| Factors contributing to the Diffusion Coefficient | D = R.T / (6.p.n.r) R Gas constant (8.3 J/K.mol) T Absolute temperature (K) n Viscosity of barrier r Radius of diffusing molecule (related to molecular weight?) |
| frictional coefficient or resistance) | P, D 1/n.r |
| Rate of solute diffusion (J) is proportional to:- | permeability coefficient P surface area A of membrane concentration difference c |
| factors for predicting passive permeability | - Frictional effects (“mobility”) :- Molecular size - small, Pup; large, Pdown Molecular shape - straight (“snake-like”) Pup ; globular Pdown Membrane viscosity - Short R chains, -C=C-, inc. To, Pup |
| factors for predicting passive permeability | Lipid solubility (Kp) :- Kp high (e.g. O2, CO2, anaesthetics, lipophilic group), P up Kp low (e.g. sugars, amino acids, ions, polar / charged groups), Pdown |
| factors for predicting passive permeability | Unstirred Layers :- increases overall “thickness” of barrier |
| factors for predicting passive permeability | Charge effects :- (cation e.g. ) Molecular charge affects Kp Hydrogen-bonding alters effective molecular size / shape, Kp |
| osmolarity | the total concentration of all the particles that are free in the solution proportional to concentration of dissolved solutes inversely proportional to osmotic potential |
Created by:
raisyasmine36
Popular Biology sets