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1. W A T E R I S
5 0 % O F B O D Y W E I G H T I N W O M E N
6 0 % I N M E N
w w w . m e d i c i n e m c q . c o m
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FLUID DISTURBANCES
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2. Intracellular fluid (ICF)
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• Largest compartment – 60%
• Main cation – potassium
• Anions - phosphates and bicarbonate
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3. 3www.medicinemcq.com

4. ECF = 40%
4
• Main cation – sodium
• Anions - chloride and bicarbonate
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5. 5www.medicinemcq.com

6. 6www.medicinemcq.com

7. If 1 L of solute-free water is lost from the body, how
much fluid is lost by the ICF compartment?
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 Water ICF : ECF = 2:1 ratio
 Solute-free water loss
 Twofold greater reduction in the ICF compartment
than the ECF compartment
 Volume loss
 ICF = 667 mL
 ECF = 333 mL
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8. Lose of 1L of iso-osmotic fluid
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 ECF compartment will decrease by 1 L
 Na+ is largely restricted to the ECF
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9. Osmolality and osmolarity
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 Often used interchangeably
 Osmolality
 Number of solutes per mass of water
 Osmolarity
 Number of moles of solute in a liter of solution
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10. Solutes
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 Extracellular and intracellular solutes (or
osmoles)
 Markedly different
 Water
 Moves across cell membranes
 Distributes between ICF and ECF
 Until the osmolality is the same
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