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25 Cards in this Set
- Front
- Back
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WHAT ARE THE VARIOUS BODY FLUID COMPARTMENTS
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Body Fluid = 60% of Body Weight
Intracellular Fluid - ICF Extracellular Fluid - ECF - Interstitial Fluid - ISF - Vascular Compartment - Plasma |
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RELATIVE VOLUMES OF FLUID COMPARTMENTS
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ICF - 66% of Body Fluid
ECF - 33% of Body Fluid ISF - 75% of ECF = 25% of Body Fluid Plasma - 25% of ECF = 8% of Body Fluid |
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IONIC COMPOSITION OF FLUID COMPARTMENTS
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mEq/L ECF ICF
Na+ 145 12 K+ 4 150 Ca2+ 5 0.001 Cl- 105 5 HCO3- 25 12 Pi 2 100 pH 7.4 7.1 |
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OSMOLARITY
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# of moles of osmotically active particles - OSMOLES in one litre of SOLUTION
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OSMOLALITY
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# of moles of osmotically active particles - OSMOLES in one kilogram of solvent
osmoles / kg |
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EQUIVALENCE
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Number that is equivalent to the number of charges in a quantity of charged particles
ie a mole of Ca2+ has an equivalence of 2 moles |
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MOLARITY
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# of moles grams/molecular weight in a litre of solution
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PLASMA OSMOLALITY
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2 x Plasma [Na] + [Glc] + [Urea]
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EFFECTIVE PLASMA OSMOLALITY
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glucose and urea freely permeate the cell membrane tf are not osmotically effective
Effective Plasma Osmolality is twice the plasma [Na] |
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OSMOTICALLY ACTIVE
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solutes which can not cross a semipermiable membrane which is freely permeable to the solvent
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OSMOTIC EQUILLIBRIUM
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Except for transient changes the osmolality of the ECF and ICF are equivalent because water is freely permable to cell membranes
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OSMOTIC PRESSURE
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The hydrostatic pressure required to stop osmosis
1 mOsm/L = 19.3 mmHg Osmotic Pressure |
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OSMOSIS
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Movement of solvent across a membrane which is selectively permeable to the solvent but impermeable to solutes, making the solutes osmotically active, from the compartment of lower concentration of osmotically active particles to the compartment of higher concentration of osmotically active particles
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ONCOTIC PRESSURE
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aka Plasma Colloid Osmostic Pressure
Osmotic pressure exerted by plasm proteins |
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ISOSMOTIC
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Equal osmolality across a selectively permeable membrane
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ISOTONIC
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Equal osmolality of impermeant solutes across a erythrocyte membrane
ISOTONIC rbc volume unchanged HYPOTONIC rbc volume increases HYPERTONIC rbc volume decreases |
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SPECIFIC GRAVITY
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Density of solution relative to water
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STARLINGS FORCES
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Responsible for the movement of fluid across the capillary wall
OUT - Capillary Hydrostatic Pressure (Pc) - Interstitial Fluid Colloid Osmotic Pressure (Πif) IN - Interstitial Fluid Hydrostatic Pressure (Pif) - Plasma Colloid Osmotic Pressure (Πp) |
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NET FILTRATION PRESSURE (NPF)
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NPF = (Pc)+ (Πif) - (Pc) - (Πp)
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FLUID MOVEMENT BETWEEN ECF AND ICF
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Occurs due to forces generated by transient differences in osmotic pressure between the ECF and ICF
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5 PATHOPHYSIOLOGIC CONDITIONS
THAT REDUCE ICF RELATIVE TO ECF |
Dehydration
Diarrhea Diuresis Vomition Excercise |
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EFFECT ON ECF AND ICF OF ADDING ISOTONIC SALINE SOLUTION TO ECF
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Increases volume of ECF by amount of saline added - ICF volume unchanged.
Isotonic saline does not change the osmolarity of the ECF tf the osmolarity of the ECF remains the same as the ICF tf there is no net movement of fluid |
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EFFECT ON ECF AND ICF OF ADDING HYPOTONIC SALINE SOLUTION TO ECF
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Decreases volume of ECF -increases volume of ICF.
Adding hypotonic saline to the EFC reduces its molarity tf fluid will move to ICF until the osmolarity of the ECF is raised and the osmolarity of the ICF is lowered to the point were there is no osmotic pressure difference between ECF and ICF |
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EFFECT ON ECF AND ICF OF ADDING HYPERTONIC SALINE SOLUTION TO ECF
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Increases volume of ECF - decreases volume of ICF.
Adding hypertonic saline to the EFC increases its molarity tf fluid will move from ICF until the osmolarity of the ECF is lowered and the osmolarity of the ICF is raised to the point were there is no osmotic pressure difference between ECF and ICF |
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ISOTONIC SALINE SOLUTION
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0.9% NaCl - 290 mOsm/kg H2O
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