Cell Volume Regulation Flashcards
What is diffusion?
random, thermally-agitated movement of molecules
“random walk of diffusing particles”
What is osmosis?
spontaneous net movement of solvent molecules across selectively permeable membrane into a region of higher solute concentration
The movement of what molecules can change the volume of a cell
Water
What 3 mechanisms have evolved to prevent cells from swelling and bursting?
- Cell Wall: plants, fungi & bacteria (hydrostatic force metabolically expensive!!)
- Animal Cell: allow solute molecules in ECF - water ACTIVITY is equal on both sides of plasma membrane (identity of solutes is unimportant -concentration matters)
What is the equation for osmotic pressure?
Pie (osmotic pressure) = RTdeltaC
R = gas constant
T - temp in kelvin
delta C = difference in concentration
What is tonicity?
measure of the osmotic pressure gradient of two solutions separated by a semipermeable membrane
What is osmolarity?
concentration of an osmotic solution
measure of solute concentration:
#osmoles of solute/L
aka osmotic concentration
What is molarity?
of moles/ unit volume
What are equivalents?
having the same ability to combine
What is the reflection coefficient?
0 for THO, 1 for non-permiating solution
- measure of how well membrane “reflects” solute
How does permeability affect diffusion?
permeability of solutes can be slower that water-> reverse flow at first, until water catches up
- ex) dehydrated infant (blister grows- capillaries more permeable to NaCl- then water flows back in => equilibrium)
ex) new onset DM: hyperosmotic blood (blood capillaries less permiable -> as plasma glucose decreases -> glucose stranded in brain -> plasma is hypo osmotic -> water into brain! EDEMA/ pressure)
How do you convert between osmolarity and equivalents?
multiply osmolarity by valence
in uncharged solutes, mEq = mM
