Passive Transport Flashcards
Passive process
1) Diffusion
2) Simple diffusion
3) Facilitated diffusion
4) Osmosis
Diffusion is influenced by
- Steepness (of concentration gradient)
- Temperature
- Mass (of diffusion substance)
- Surface area
- Diffusion distance
2 Facilitated Diffusion processes
1) Channel-mediated
2) Carrier-mediated
Osmosis
net movement of a solvent through a selectively permeable membrane from an area of high concentration
—> an area of low concentration
Tonicity of solution
how the solution influences the shape of body cells
- Hydrostatic pressure
- Osmotic pressure
Transmembrane proteins
help solutes (that are too polar or too highly charged) move through the lipid bilayer
Passive process
Movement of substances down a concentration gradient until equilibrium is reached; no required cellular energy in form of ATP
1) Diffusion
- Movement of molecules / ions down concentration gradient … due to their kinetic energy
- until they reach equilibrium.
2) Simple diffusion
- Movement of substance down its concentration gradient through lipid bilayer
- without help of membrane transport proteins
Simple diffusion transports
Non-polar / hydrophobic solutes: oxygen, carbon dioxide, and nitrogen gases; fatty
acids; steroids; & fat-soluble vitamins.
Polar molecules : water, urea, & small alcohols.
3) Facilitated diffusion
- Movement of substance down its concentration gradient through lipid bilayer
- by transmembrane proteins ; function as channels / carriers
Facilitated diffusion transports
Polar / charged solutes: glucose; fructose; galactose; some vitamins
Ions: K+, Cl−, Na+, and Ca2+
4) Osmosis
Movement of water molecules across a selectively permeable membrane from an area of higher
—>lower water concentration until equilibrium is reached.
Osmosis transports
Solvent: water in living systems
