DSA: Osmosis Flashcards
What is a SOLVENT?
Fluid that serves as the “base” for the solution
*In human body, the solvent is water
What is a SOLUTE?
Substance that is dissolved to make the solution
*In human body, solutes include the ions, proteins, steroids, etc…
Osmosis produces a significant change in the __________ of the two solutions; the more concentrated solution will _______ in volume as the solvent moves from the less concentrated solution to balance the two solutions
VOLUME, INCREASE
Describe DIFFUSION
- Movement of the solute across a membrane when there is a concentration gradient
- Moves from high concentration to low concentration
Describe OSMOSIS
- Movement of the SOLVENT
- Result in pressure gradient
In the body: the solvent is:
Water
In the body: solutes are:
ions, proteins
*Despite the different ion concentrations in the intra- versus extracellular fluid, the osmolarity of the two is _________
the same
*Osmosis ___________ the concentration of solutes
doesn’t depend on
*Osmosis only occurs if
There is a gradient for the water
Which ion(s) are in higher concentration in the ECF?
- Sodium
- Chloride
- Calcium
- Bicarbonate
Which ion(s) are in higher concentration in the ICF?
Potassium
The osmolarity of the ICF and ECF are:
THE SAME, no gradient for osmosis to occur
What does OSMOLARITY measure?
Number of osmotically active particles (solute) in the solution
Osmolarity is measured in units of ________
osmoles
In the body, osmolarity is measured in ________
milliosmoles (mOsm)
1/1000 of an Osmole
How to calculate osmolarity?
Osmolarity= g x [C]
Osmolarity calculation:
g=1 if:
the solute doesn’t dissociate
Osmolarity calculation:
examples of g=1?
Glucose, urea, proteins
Osmolarity calculation:
g>1 if:
the solute dissociates when placed in solution
Osmolarity calculation:
examples of g>1?
NaCl
g=2 if the NaCl were to completely dissociate into Na and Cl
The measured g=1.8 because not all the NaCl dissociates
CaCl2
g=3 at a max
What is the reflection coefficient?
Measure of the solute’s permeability across the membrane
Ranges b/w 0-1
0=solute is fully permeable across the membrane
1= solute is completely impermeable across the membrane
***Important b/c tells if OSMOSIS WILL OCCUR
If the reflection coefficient is 0, osmosis ______ occur
WILL NOT
If the reflection coefficient is 1, osmosis ______ occur
WILL
What is the average osmolarity of the ICF and ECF of the human body?
290 mOsm
What is the normal range for osmolarity in the human body?
270-300 mOsm
A 0.9% solution of sodium chloride is ________ to RBCs
Isosmotic
*Normal saline
What is a CMP?
Complete metabolic profile
What is the equation used for estimating osmolality?
=(2x [Na]) + ( [glucose]/18) + ([BUN]/2.8)
