pathophysiology-ii-nsg-3850-unit-1-fluid-electrolyte-homeostasis.pdf

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Patho II NSG 3850 Unit 1 Fluid Electrolytes


Pathophysiology For Nurses II (Galen College of Nursing)

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Pathophysiology II NSG 3850 Unit 1: Fluid and Electrolyte Homeostasis and Imbalances

Body Fluid Homeostasis
Definition of Body Fluid
 Water within the body and the particles dissolved in it
 Exists in:
o Intracellular fluid (ICF)
o Extracellular fluid (ECF)
 In all age groups except infants:
o About 2/3 of body fluid is intracellular
o About 1/3 is extracellular
 In infants (reversed):
o About 2/3 of body fluid is extracellular
o About 1/3 is intracellular
 Infants and elderly adults are at risk for dehydration
o Due to immature hypothalamus in infants
o Worn out hypothalamus, slow osmoreceptors in elderly
o Body composition—increased fat, decreased muscles in elderly
Total Body Water
 Varies based on:
o Age
o Body fat proportion
 Adult male:
o About 60% body weight is water
o More muscles than fat
o Muscles hold more blood/water than fat
 Adult female:
o About 50% body weight is water
o More fat than muscles
 Total body water decreases with aging

Fluid Compartments
Extracellular Fluid (ECF)
 Interstitial fluid (between cells)
 Vascular compartment (blood vessels)
 Transcellular fluid:
o Synovial
o Cerebrospinal
o Gastrointestinal
Total body water
o Total amount of water in all fluid compartment
Intracellular Compartment
 High in:
o Potassium
o Magnesium
o Proteins
o Phosphates
 Low in:
o Sodium, Chloride
Extracellular Compartment
 Vascular:
o Rich in protein
 Interstitial:
o Few proteins
 High in: