PHYSIOLOGY - Movement Across Membranes Flashcards
What is the driving force behind diffusion
The kinetic energy of the molecules
Define differential permeability
The plasma membrane of a cell is selectively permeable. It allows useful substances in but keeps out harmful substances. It also keeps valuable proteins etc in the cell.
Define osmolarity
A measure of the concentration of osmotically active particles in a solution
How to calculate osmolarity
Molar it’s x dissociation factor ( dissociation factor of NaCl is 2, it divides into 2 ions )
Define tonicity
Tonicity predicts the effect of a solution on the volume of the cell at equilibrium. It depends on the relative concentrations of non-penetrating (osmotically active) solutes in the cell and in the solution.
Hypertonic
Water moves out of the cell. The concentration of osmotically active particles in the ECF is higher than in ICF
Isotonic
No net movement of water. Concentration of osmotically active particles is equal in ECF and ICF
Hypotonic
Water moves into cell. Concentration of osmotically active particles in ICF is higher than in ECF
Osmolarity
Number of osmoles in 1L of solution
Osmolality
Number of osmoles in 1 Kg of solution
Hyperosmotic
ECF solute conc is greater than ICF solute conc
Isosmotic
ECF solute conc = ICF solute conc
Hypotonic
ECF solute conc less than ICF solute conc
A solution with a high osmotic pressure makes water flow in? Or out?
In
If the ECF has a higher osmotic pressure than the ICF the ECF is hypertonic/hypotonic/isotonic to the ICF?
Hypertonic
