osmosis
passive transport of water across the membrane
aquaporins
water channel proteins, allow water into the cell, enhances water transport via osmosis
the more aquaporins in the membrane….
the more water permeable the membrane is
membrane potential
the difference in voltage across the cell membrane
how is osmolarity measured
in osmoles (osm)
differences between intracellular and extracellular fluids
ionic and molecular composition differs, but osmolarity and osmotic pressure are the same
1 osm is equal to how many molecules in a liter
6.022 x 10^23, avogadro’s number
osmolality
molarity per mass of solvent (mmol/ kg)
isomotic
2 or more solutions have the same osomolarities
why are intra and extracellular fluids similar in osmolarity
if they are too different from each other the cells can lyse or dry out
what happens when NaCl dissolves in water
separates into Na+ and Cl-, increasing the osmolarity since there’s now two particles instead of one
what happens to osmolarity when MgCl2 dissolves in water
separates into Mg, Cl, and Cl; increasing osmolarity from one particle to three
what happens when glucose dissolves in water
glucose stays as glucose, does not increase osmolarity
osmotic pressure
tendency of a solution to gain/ lose water, a physical force that drives water from one location to another, only when there’s a difference in osmolarity
hydrostatic pressure
contraction/ reduction of volume pushes fluid from high to low pressure
how does water move in osmolarity
from low to high osmolarity; since there’s less water molecules in a solution with more stuff dissolved in it (concentration gradient)
how does water molecules move in pure water to a solution higher in osmolarity
only in one direction; to the higher osm solution since pure water has osmolarity of zero
osmoregulation
maintenance of a nearly constant osmotic pressure in plasma
high osmotic pressure
gains water (high osmolarity)
low osmotic pressure
loses water (low osmolarity)
hyperosmotic
solution has higher osmolarity than surrounding fluids
hyposomotic
solution has lower osmolarity to surrounding fluids
osmoconformers
internal osmolarity changes w/ environment
osmoregulators
internal osmolarity stays constant through expending energy
partial osmoregulator
can regulate osmolarity to a point then it conforms
what is the normal osmotic pressure for plasma in freshwater or saltwater fish
300 mOsm
if someone has alcohol poisoning you use
saline solution to hydrate since if you add pure water it causes cells to lyse
if a saltwater clam is thrown in freshwater what happens?
osmotic pressure goes from high to low, volume increases, extracellular fluid pressure decreases