Topic 5 Fluid Compartements & Fluid Shifts Flashcards
Distribution between plasma and interstitial compartments is controlled by what? (4)
forces moving fluid into and out of the capillaries -Capillary hydrostatic pressure -Interstitial hydrostatic pressure -Capillary colloid oncotic pressure -Interstitial colloid oncotic pressure
Distribution between intracellular and extracellular compartments is controlled by what mainly?
osmotic effect of sodium & chloride (mainly) across cell membranes
Cell membranes: permeability?
- high permeability to water
- low permeability to solute
Water moves quickly into or out of the cell to keep ICF isotonic with ECF
Osmole -
means of measuring total concentration of particles in solution
1 osmole = 1 mole of particles (6.02 x 1023)
Each mOsm of solute that cannot cross the membrane will generate an osmotic pressure of what?
of 19.3 mmHg
osmotic gradient across the cell membrane: how do you calculate?
Intracellular osmolarity x 19.3mmHg (Pressure each mOsm of solute that cant cross membrane generates) = osmotic gradient across cell
EX: Exposing RBC with intracellular osmolarity of 300 mmHg to pure water would result in an osmotic gradient across the cell membrane of 5790 mmHg
Interstitial/ intracelluar and plasma mOsm/L are all about what?
300 mOsm/L
Small changes in the concentration of impermeable solute will create large shifts of what? creating Lrg changes in what as well?
water creating large changes in compartment volumes
0.9% Sodium Chloride (0.9 grams of NaCl /100 mls solution–9 grams / L) is what kind of solution?
Isotonic Solution
Hypo-osmotic Solutions?
Solutions with lower osmolarity than intracellular fluid even if some solute is
permeable
Hyperosmotic Solutions?
Solutions with higher osmolarity than intracellular fluid even if some solute is permeable
Causes of imbalance (4)
Water ingestion
Dehydration
Fluid loss from gastrointestinal tract
Abnormal fluid loss by sweating or kidneys
If you add Normal Saline to a solution and the Osmolarity of solution is the same as ECF.
- what happens to ECF osmolarity?
- what happens ECF volume?
Think of graph
No change in ECF osmolarity
Expand volume of ECF by volume of solution
(the liter starts in the plasma of the CBV within 15 minutes 75% will move to the Interstitial fluid–25% will remain in the CBV)
If you add Hypertonic Solution to a solution?
- what happens to ECF osmolarity/volume?
- what happens to ICF osmolarity/volume?
Think of graph
ECF Osmolarity & VOL INCREASE
ICF VOL Decreases & Osmolarity Increases
- Osmolarity of solution higher than osmolarity of ECF so ECF osmolarity will increase
- Osmolarity of ECF > than osmolarity of ICF so water moves from ICF to ECF
- Overall increase in osmolarity
- ECF volume increases (more than the volume added)
- Most of the sodium and chloride remains in the ECF
If you add Hyportonic Solution to a solution?
- what happens to ECF osmolarity/volume?
- what happens to ICF osmolarity/volume?
Think of graph
ECF Osmolarity Decrease & Vol Increase
ICF Osmalarity Decrease & Vol Increse
- Osmolarity of solution lower than osmolarity of ECF so ECF osmolarity will decrease
- Osmolarity of ECF < than osmolarity of ICF so water moves from ECF to ICF
- Overall decrease in osmolarity
Most common Nutrient solution given?
Glucose
Given IV
Nearly Isotonic (If not, given slowly so does not upset balance)
When a Nutrient Solution that was give is metabolized what is the patient often left with?
As nutrient metabolized patient often left with surplus of water
Usually removed via kidneys
What is a good measure for plasma osmolarity?
Plasma Sodium Concentration
Sodium and chloride account for 90% of solute in ECF