Mem Transport 1 - Passive Processes Flashcards
What are two properties which influence whether a particle can permeate the plasma mem without assistance
Solubility of particle in lipid
Mass of particle
What are some driving forces
Passive - comic grad, electrical grad
Active - requires cell to expend energy by hydrolysis of atp
What happens in unassisted mem transport
Molecules and ions that can penetrate the mem passively
Driven by: diffusion down conc grad and electrical grad
Absence of transporters etc the NON-POLAR interior of cell mem prevents pass of large water sol molecules and ions
What is simple diffusion in a solution
Diffusion of biologically relevant small molecules in solution is extremely slow
It is only effective over microscopic distances
One reason for circulatory system
Why is movement by diffusion so slow
Each molecule, in solution takes random walk
Effective diff across bio mem occurs coz they are extremely thin and distance minuscule
How does diffusion work
Movement of a particle completely random walk
When diffusion occurs what is the eqn
Flux (J) = permeability coeff (P) x conc grad
What is Ficks law of diffusion
Several factors In addition to conc grad influence the rate of net of diffusion across the mem and Collectively made up Ficks law of diff
- mag of conc grad
- SA of diff surface
- lipid sol
- molecular weight sub diff
- distance to diff
How doe ions move down electrical grad
Ions
In addition to conc grad move down electrochem grad
Cations to negative enviro
Diff In charge between two adjacent areas gen an electrical gradient
What is osmosis
Net diff water down its conc grad across semi perm mem
Water but not solute moves across mem
Hydrostatic pressure difference develops
Dynamic equilibrium reached if non per meant sub present
What su osmotic pressure
Pressure that arises from unequal solute concs across semi perm mem
Portionel to conc of solute
Colligative property depo on dissolved particles
What su the eqn for osmotic pressure
N = RTCsolute
R = universal gas constant T= absolute temp
What is the way water moves through the mem
Occurs due to constant motion of phospholipid tails that result in transient pores that allow water molecules to slip though
Aquaporins - channel that’s conduct water selectivity, greatly increase perm to water
What is the osmolarity
The conc of osmotically active particles present in sol
Number not mass
What su tonicity
Effect a solution has on cel volume ISO Hypo Hyper No units
