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25 Cards in this Set

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WHAT ARE THE VARIOUS BODY FLUID COMPARTMENTS
Body Fluid = 60% of Body Weight

Intracellular Fluid - ICF

Extracellular Fluid - ECF
- Interstitial Fluid - ISF
- Vascular Compartment - Plasma
RELATIVE VOLUMES OF FLUID COMPARTMENTS
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
IONIC COMPOSITION OF FLUID COMPARTMENTS
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
OSMOLARITY
# of moles of osmotically active particles - OSMOLES in one litre of SOLUTION
OSMOLALITY
# of moles of osmotically active particles - OSMOLES in one kilogram of solvent

osmoles / kg
EQUIVALENCE
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
MOLARITY
# of moles grams/molecular weight in a litre of solution
PLASMA OSMOLALITY
2 x Plasma [Na] + [Glc] + [Urea]
EFFECTIVE PLASMA OSMOLALITY
glucose and urea freely permeate the cell membrane tf are not osmotically effective

Effective Plasma Osmolality is twice the plasma [Na]
OSMOTICALLY ACTIVE
solutes which can not cross a semipermiable membrane which is freely permeable to the solvent
OSMOTIC EQUILLIBRIUM
Except for transient changes the osmolality of the ECF and ICF are equivalent because water is freely permable to cell membranes
OSMOTIC PRESSURE
The hydrostatic pressure required to stop osmosis

1 mOsm/L = 19.3 mmHg Osmotic Pressure
OSMOSIS
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
ONCOTIC PRESSURE
aka Plasma Colloid Osmostic Pressure

Osmotic pressure exerted by plasm proteins
ISOSMOTIC
Equal osmolality across a selectively permeable membrane
ISOTONIC
Equal osmolality of impermeant solutes across a erythrocyte membrane

ISOTONIC rbc volume unchanged
HYPOTONIC rbc volume increases
HYPERTONIC rbc volume decreases
SPECIFIC GRAVITY
Density of solution relative to water
STARLINGS FORCES
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)
NET FILTRATION PRESSURE (NPF)
NPF = (Pc)+ (Πif) - (Pc) - (Πp)
FLUID MOVEMENT BETWEEN ECF AND ICF
Occurs due to forces generated by transient differences in osmotic pressure between the ECF and ICF
5 PATHOPHYSIOLOGIC CONDITIONS
THAT
REDUCE ICF RELATIVE TO ECF
Dehydration
Diarrhea
Diuresis
Vomition
Excercise
EFFECT ON ECF AND ICF OF ADDING ISOTONIC SALINE SOLUTION TO ECF
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
EFFECT ON ECF AND ICF OF ADDING HYPOTONIC SALINE SOLUTION TO ECF
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
EFFECT ON ECF AND ICF OF ADDING HYPERTONIC SALINE SOLUTION TO ECF
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
ISOTONIC SALINE SOLUTION
0.9% NaCl - 290 mOsm/kg H2O