Mem Transport 1 - Passive Processes Flashcards Preview

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Flashcards in Mem Transport 1 - Passive Processes Deck (16):

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

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
No units


What su the perm of plasma mem

Selective perm assisted by transporters and pumps etc