Biological membranes & Cellular Transport

Endocytosis

move large or many items from out to in via endosomes that may fuse w/lysomes for degnaditon 

Exocytosis

move large or many items from in to out via secretory vesicles

Secretion

substances exit cell for system function (insulin, cholesterol)

gradient

continuously changing variable across space (concentration, charge)

chemical gradient

concentration only

electrochemical gradient 

charge+concentration 

diffusion 

solute non-polar moves from greater(solute) to lesser(solute) through phospholipid bilayer (gases) 

facilitated diffusion

polar charged solutes move from greater (solute) to lesser (solute) through protein channel or carrier (Na+, and K+ via voltage-gated channels , glucose)

against gradient

solute moves from lesser (solute) to greater (solute) via active transport

Isotonic

=, normal

Hypotonic 

H2O in, swollen, 0.8<2.0

Hypertonic

H2O out, shriveled, 0.8>0.1