Human Body Fluids Quiz

Study Notes

50-60% of body weight is water & divided into intracellular fluid (ICF) and extracellular fluid (ECF).
ICF is inside cells, comprising 40% of body weight.
ECF is outside cells, comprising 20% of body weight and further divided into interstitial fluid (15%) and intravascular fluid (5%).
Transcellular fluid includes CSF, pleural, peritoneal, and synovial fluids.
Amount of water varies by age and sex; infants have a higher percentage, and body water decreases with age.

Isotonic Fluids have a concentration of solutes comparable to 0.9% NaCl, maintaining equilibrium without causing fluid shifts.
- Examples: Normal saline (0.9% NaCl).
- Uses: Volume replacement in hypovolemia, dehydration, and shock. Maintenance fluids during surgery and for patients unable to take fluids orally.
Hypertonic Fluids have a higher concentration of solutes compared to plasma, drawing water out of cells.
- Examples: 3% NaCl.
- Uses: Severe hyponatremia, cerebral edema, severe hypoglycemia. Acute care requiring rapid fluid and solute correction.
Hypotonic Fluids have a lower concentration of solutes compared to plasma, causing water to move into cells.
- Examples: 0.45% NaCl, 0.33% NaCl solutions.
- Uses: Cellular dehydration in diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). Hypernatremia and as maintenance fluids for patients at risk of hypernatremia or hyperchloremia.
D5 Water: Isotonic solution outside the body but becomes hypotonic once administered.

Osmosis: Movement of water across a membrane from a low solute concentration to a higher concentration.
- Example: Water moving into cells to balance solute levels.
Diffusion: Movement of particles (solutes) from a high to a low concentration. Influenced by factors like size, concentration, and temperature.
- Example: Oxygen moving from the lungs into the bloodstream.
Filtration: Movement of water and solutes from an area of high pressure to low pressure.
- Hydrostatic pressure helps push fluids in this process.
Facilitated diffusion: Passive transport process that allows larger or polar molecules to cross cell membranes with the help of transport proteins (carrier proteins or channels).
Active Transport: Uses energy (ATP) to move solutes from a low concentration to a high concentration.
- Example: Sodium-potassium pump in cells.
Translocation: Continuous movement of fluids and chemicals between compartments to maintain balance.
- Example, electrolytes like sodium and potassium move between cells and extracellular fluid to regulate nerve impulses and muscle function.

Sources: Food intake, ingested fluids, medications, IV fluids, TPN solutions.
Dynamics: Distribution, excretion, and regulation.
Average dietary intake of sodium is about 6-14 g/day.
- 1 tsp of table salt = 2000 mg
- 1 tsp soy sauce = 1029 mg