Forces Across Membranes 3 Flashcards
What is osmosis?
Net movement of water from regions of high concentration to regions of low concentrations
What is diffusion?
Net movement of solute from regions of high concentration to regions of low concentration
How does the body maintain osmotic equilbrium?
By water moving freely between the ECF and ICF
What relationship does the concentration of H2O have to the concentration of solute?
Inversely related, the more solute particles the more they displace water
What must the concentration and volume of water and solute of a membrane permeable to both be?
The same
In terms of volume and water, how are they different across a membrane if it is only permeable to water and not the solute?
The same concentration of water on either side but a different volume
What is osmotic pressure?
Pressure that must be applied to stop osmotic movement
What is concentration expressed as?
mol/L
How many molecules are in 1 mol
6.02x1023 molecules
What does a concentration of 1M mean?
Concentration of 1 mol/L
What determines the osmotic effect of water (particles or molecules)?
The number of particicles, for example:
1 mole of glucose added to 1L of water reduces [H2O] by 1 mole/L
1 mole of NaCl added to 1L of water reduces [H2O] by 2 mole/L
What is osmolarity?
Measure of concentration of biological solutions in units of Osmoles
What is osmole?
Describes the number of particles per L of solution
Give examples of the use of Osmole as a unit?
1M solution of glucose has an osmolarity of 1osmol/L
1M of NaCl has an osmolarity of 2osmol/L
What does normal plasma have an osmolarity of and how does this compare to within cells?
285mOsmol/L, which is the same within cells
What does osmolarity not describe which is important?
The nature of the particles (if they can cross the membrane)
What does osmolarity describe?
The number of particles in solution
What happens to water when the concentration of a solute which cannot pass the membrane changes?
Change in concentration creates an osmotic flux which causes a net movemet of water
What does a net movement of water cause?
A change in volume
What is the volume of a cell dependent on?
The concentration of non penetrating solutes on either side of the membrane
What is osmolarity?
Describes the total number of particles in solution
What is tonicity?
Describes the total number of non penetrating particles in solution
What definitions do osmolarity use?
Isometric
Hypoosmotic
Hyperosmotic
What does isometric mean?
Same total number of solute particles as ECF)
What does hypoosmotic mean?
Fewer total number of solute particles
What does hyperosmotic mean?
Greater total of solute particles than ECF
What definitions does tonicity use?
Isotonic
Hypotonic
Hypertonic
What does isotonic mean?
Same number of non penetrating solute particles as normal ECF
What does hypotonic mean?
Few number of non penetrating particles than ECF
What does hypertonic mean?
Greater number of non penetrating solute particles than ECF
What happens to cells in a hypotonic solution?
Swell as water moves down the chemical gradient into the cell
What happens to cells in a hypertonic solution?
Shrink as water moves down the chemical gradient out of the cell
What is intravascular haemolysis?
Cells bursting, which can kill due to introducing proteins in the ECF increasing the tonicity
