Water & regulation of extra/intracellular fluids
- Georgia State University
- Nutrition 6106
- Water & regulation of extra/intracellular fluids
Last Modified: 2011-07-09
- is a measure of solute conc. defined as number of osmoles of solute per liter of solution (osmol/L) –temp. dependent (if temp goes up, volume expands)
- 1 osmole/L
- specific for molecules exerting osmotic pressure
- is a measure of the osmoles of solute per kilogram of solvent
- not temp dependent (because weight is not temp dependent)
- ~60% (24L), the major portion of your body water.
- inside the cell
- Interstitial fluid (ISF)
- Transcellular fluid
- surrounds the cells, but does not circulate
- comprises about 28% (11.2L) of the total body fluid
- intravascular fluid, circulates as the extracelluar component of blood
- makes up 8% of (3.2L) of total body fluid
- hydration goes up /dehydration goes down
- most important with kidney fx and water homeostasis
- cardiac output
- set of fluids outside the normal compartments
- 1-2 L of fluid
- CSF, digestive juices, mucus, 4% of total body fluid
- Total Body Water (TBW)
- ECF volume
- Plasma volume
- Use D20 (deuterated water) or radioactive water, Distributes throughout all aqueous solutions. radioactive shows up everywhere
Use radioactive Inulin (Stable Isotope) fructo-oligosaccharide
-Distribute throughout body, but are excluded from cells
only stays in extracelluar fluid.
Use radioactive albumin, stays in plasma only.
Interstitial volume =
- (i.e., 6.02x1023 molecules)
- the weight in grams (mole) of an ionic substance that replaces or combines with one gram (mole) of monovalent H+ ions.
- (Ca+2, Mg+2, HPO4-2) 1 Eq = ½ of a GMW
- Physiological concentrations are often measured in
- mEq/L = 10-3 Eq/L. These units are useful when considering how much of a substance is needed to maintain electroneutrality.
- (food & drink) 2.2L/day
- (skin & lungs) 0.9L/day
- (metabolism) 0.3L/day
- (urine) 1.5L/day
- (feces) 0.1L/day
- Glucose + O2 -> CO2 + H20 + ATP
- 0.9 + 0.1 + 1.5
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