Chapter 1 - Physiology of Body Fluids Flashcards
What does this refer to:
The number of solute particles per 1 L of solvent
Osmolarity
Temperature dependent because the volume of solvent varies with temperature (i.e., the volume is larger at higher temperatures).
What does this refer to:
The number of solute particles in 1 kg of solvent
Osmolality
Is based on the mass of the solvent and is temperature independent.
The ________ of a solution is related to its effect on the volume of a cell.
The tonicity of a solution is related to its effect on the volume of a cell; tonicity also takes into consideration the ability of the solute to cross the cell membrane.
Solutions that do not change the volume of a cell are said to be _______. A _________ solution causes a cell to swell, whereas a _________ solution causes a cell to shrink.
Solutions that do not change the volume of a cell are said to be isotonic. A hypotonic solution causes a cell to swell, whereas a hypertonic solution causes a cell to shrink.
σ is the ______ _________ or ________ ________ and is a measure of the relative ability of the solute to cross a cell membrane.
σ is the reflection coefficient or osmotic coefficient and is a measure of the relative ability of the solute to cross a cell membrane.
The total solute concentration in a solution also can be measured as specific gravity. Define specific gravity.
Specific gravity is defined as the weight of a volume of solution divided by the weight of an equal volume of distilled water.
What is the breakdown for total body water composition?
Total body water is distributed between two major compartments, which are divided by the cell membrane.* The intracellular fluid (ICF) compartment is the larger compartment and contains approximately 2/3 of the total body water. The remaining 1/3 of the body water is contained in the extracellular fluid (ECF) compartment.
What is this describing?
Plasma proteins have a net negative charge that tends to increase the cation concentrations and reduce the anion concentrations in the plasma compartment.
Donnan Effect
What is a quick and easy way to determine ECF osmolality
Na+ (and its attendant anions, primarily Cl− and ) is the major determinant of ECF osmolality. A rough estimate of the ECF osmolality can be obtained by simply doubling the sodium concentration [Na+]. For example, if the plasma [Na+] is 145 mEq/L, the osmolality of plasma and ECF can be estimated as: 290 mOsm/kg H2O
What is the equation for plasma osmolality?
[2(Na+) + [glucose]/18 + [Urea]/2.8]
The glucose and urea concentrations are expressed in units of mg/dL (dividing by 18 for glucose and 2.8 for urea* allows conversion from the units of mg/dL to mmol/L and thus to mOsm/kg H2O). This estimation of plasma osmolality is especially useful when dealing with patients who have an elevated plasma [glucose] level as a result of diabetes mellitus and patients with chronic renal failure whose plasma [urea] level is elevated.
What is Starling’s Equation?
Filtration Rate = Kf [(Pc-Pi) - filtration coefficient (oncotic pressure of the plasma - oncotic pressure of the interstitial fluid)]
The filtration rate is the volume of fluid moving across the capillary wall (expressed in units of either volume/capillary surface area or volume/time) and where Kf is the filtration coefficient of the capillary wall, Pc is hydrostatic pressure within the capillary lumen, πc is oncotic pressure of the plasma, Pi is hydrostatic pressure of the interstitial fluid, πi is oncotic pressure of the interstitial fluid, and σ is the reflection coefficient for proteins across the capillary wall.
How is administration of D5W equivalent to infusion of distilled water?
Administration of D5W is equivalent to infusion of distilled water because the dextrose is metabolized to CO2 and water.
A patient with a BG of 110, Urea of 36 and sodium of 165. What is the patient’s osmolality? (JClark)
348
What is the main route that water is moved in and out of the cells? (JClark)
Hydrostatic pressure and osmotic pressure
