ions Flashcards
what is diffusion
the process where atoms or molecules intermingle because of their random thermal motion
problems with diffusion in multicellular organisms
rapid of microscopic distances
slow over macroscopic
need circulatory systems to bring cells in diffusion range
cell membrane - barrier - allow concentration gradients
what is osmosis
movement of water
across a PPM
from hypotonic soln to hypertonic soln
tight junctions
stop paracellular transport
keep polarity of cell - otherwise membrane proteins would spread out
3D
tighter in stomach than in SI - SI allow water through
what modulates transcellular transport
the membrane proteins
paracellular transport
through TJ and lateral intercellular spaces
transcellular transport
through the epithelial cells
conc grad different on either side of the cell - need different membrane proteins
channel proteins
aqueous pores
allow specific solutes to pass through
carrier proteins
bind to solute - conformational change of protein
transport across membrane
do channel/carrier proteins allow faster transport
channel
just pass - no conformational change
simple diffusion
through the membrane
no membrane proteins involved
gating of ion channels
voltage
extracellular ligand
intracellular ligand
mechanically gated
types of carrier mediated transport
uniport
symport
antiport- try to equilise charge, secondary AT
Active transport
energy
enhances conc grad
primary AT
linked directly to cellular metabolism - use ATP