Body Fluid

• Two body fluid compartments:

  1. Intracellular fluid compartment - fluid inside the cells; comprises 70 % of the body fluid
  2. Extracellular fluid compartment - fluid found outside the cells; comprises 30 % of the body fluid
• Extracellular fluid compartment may be:

  • Interstitial fluid - in between the cells
  • Intravascular fluid - found in blood vessels; plasma
  • Transcellular fluid - eg. digestive juices, water in the renal tubules, pleural fluid, csf)
• The two factors that influence body water distribution are as follows: age and sex
• Age

  Infants - 80 % of body weight is water.
• Sex

  Males - 60 % of body weight is water. There is a greater amount of water in the male body. This is because males are more muscular than females. Muscle can store water.
• Sex

  Females - 50 % of body weight is water. Females have more adipose tissue than males. Fats do not store water.
• The sources of fluid intake are as follows:

  Water in food - 1000 mL

  Water from oxidation - 300 mL

  Water as taken as liquid - 1200 mL

  Total: 2500 mL/day
• The sources of fluid output are as follows:

  Skin - 500 mL

  Lungs - 300 mL

  Feces - 150 mL

  Kidneys - 1500 mL

  Total: 2500 mL/day