Membrane Transport II Flashcards
What is the term specifically used for water moving across the plasma membrane?
Osmosis
What is the name of the channel proteins that water uses to enter/exit the cell?
Aquaporins
What is the definition of Osmosis?
Movement of water across a semi-permeable membrane as a result of the concentration gradient of the solutes present in the aqueous solution on both sides of the membrane
In which direction does water move across a membrane?
From areas of low concentration to high
What is the term that represents the concentration gradient of the solutes?
Osmotic Pressure
What is another way to look at osmosis that might help make it more intuitive?
It the diffusion of water from down its own gradient…it is only confusing because water is the solvent, not the solute
What force will eventually equal osmotic pressure at equilibrium?
Hydrostatic pressure
What is osmolarity?
The number of solute particles present in the solution
What happens to the osmolarity of salts at high concentration?
It decreases slightly because at high concentrations some of the salts will not dissociate into ions
What is the expression that describes Osmotic Pressure?
Pi = RTC
R, Ideal Gas Constant
T, Temp in Kelvins
C, Total Solute Concentration (Osmolarity)
What is the osmolarity of body fluids?
7.9 atm
What is the osmotic pressure of pure water?
0 atm
What is the difference between an isotonic and an iso-osmotic solution?
The difference is that not all isotonic solutions are iso-osmotic from the cell’s standpoint.
Which solution makes the cell swell up
Hypotonic (Because the inside of the cell has fewer waters to solutes water rushes in)
What is the fancy word for cell shrikage?
Crenated
What is Osmotic Fragility?
The osmolarity of NaCl that causes hemolysis in 50% of RBCs in a sample
Why does the inhibition of the Na/K ATPase cause a cell to swell?
Because the Na/K pump help regulate the cell volume. If the pump is not working, Na ions build up in the cell creating a hypotonic solution.
What is one reason RBC might become more fragile as they age?
Reduced performance of the Sodium Pumps
