Principles of fluid balance Flashcards
Water is a polar solvent, true or false?
True
ICF and ECF have exactly the same composition, true or false?
False
Molality refers to the number of moles per _____ of a solvent.
Kg
Osmotic pressure/osmotic potential is the measure of a solution to _____ _____ water.
Take in
What is colloid osmotic pressure?
The osmotic pressure exerted by plasma colloids.
Tonicity is the effective osmolarity of a solution. How can a fluid be described with regard to serum and biological membranes?
Isotonic, hypotonic, hypertonic
What are the properties of water due to?
The presence of hydrogen bonds
How much of total body weight is due to water?
60%
Of the 60% total body weight that water makes up, how much is ICF and how much is ECF?
40% ICF
20% ECF
What makes up ECF and in what constituents?
15% ISF
5% plasma volume
<1% transcellular fluid
How is ICF formed?
Hydrostatic pressure at the arterial end of the capillary forces fluid out into the interstitium
COP at the venous end of the capillary then forces fluid back into the vessels
What ion is found in the highest quantity in the ECF?
Na
What ion is found in highest quantity in the ICF?
K
What is the difference between molarity and molality?
Molarity is the number of moles per litre
Molality is the number of moles per kg of substance
A 5M solution means 5 moles per litre. A 5 molal solution has 5 moles per kg. Molarity and molality are often equivalent as a litre of water has a mass of 1kg.
Molarity may show slight variation, but molality does not change with changes in temperature and pressure- the molality of a solution is always constant.
What is an equivalent?
The amount of material that will combine with 1 mole of OH-, H+ or electrons, e.g. in HCl, 1 mol hydrogen combines wuth 1 mol chlroine, so the amount of chlorine needed is one equivalent. In CaCl2, the combining ratio of calcium to chlorine is 1:2, so 1/2 mol Ca2+ combines with one mole Cl.