Lecture Notes: Fluid Compartments and Osmolarity Changes

Overview

• Fluid compartments: Intracellular Fluid (ICF) and Extracellular Fluid (ECF).
• Osmolarity: Concentration of solutes in body fluids; affects fluid movement between compartments.

Isotonic Fluid Loss

• Definition: Equal loss of water and solutes (e.g., salt).
• Examples: Diarrhea, vomiting, hemorrhage.
• Key Effects:
  • No change in osmolarity.
  • Decrease in ECF volume.
  • ICF remains unaffected.

Isotonic Fluid Gain

• Definition: Equal gain of water and solutes.
• Key Effects:
  • No change in osmolarity.
  • Increase in ECF volume.
  • ICF remains unaffected.

Hypotonic Fluid Loss

• Definition: Loss of more water than solutes.
• Examples: Diabetes mellitus, diabetes insipidus, dehydration.
• Key Effects:
  • Increased osmolarity (blood becomes more concentrated with solutes).
  • Decrease in ECF volume.
  • Water is pulled from ICF to ECF to balance osmolarity.

Hypotonic Fluid Gain

• Definition: Gain of more water than solutes.
• Examples: Excessive water intake, hypotonic saline administration.
• Key Effects:
  • Decreased osmolarity (blood becomes diluted).
  • Increase in ECF volume.
  • Water moves into ICF from ECF to balance osmolarity.

Hypertonic Fluid Loss

• Definition: Loss of more solutes than water.
• Example: Adrenal insufficiency.
• Key Effects:
  • Decreased osmolarity (less salt in blood).
  • Decrease in ECF volume.
  • Water moves from ECF to ICF.

Hypertonic Fluid Gain

• Definition: Gain of more solutes than water.
• Example: Syndrome of Inappropriate Antidiuretic Hormone (SIADH).
• Key Effects:
  • Increased osmolarity (more salt in blood).
  • Increase in ECF volume.
  • Water is pulled from ICF to ECF.

Conclusion

• Understanding fluid compartments and osmolarity is crucial for analyzing body fluid changes.
• Questions or topics for further explanation can be addressed in future sessions.