HLTH1004 W2 L.2.4.2

Importance of Osmosis

• Osmosis and Water Balance

  • Osmosis is crucial for maintaining water balance across plasma membranes.

  • Ensures that osmotic concentration (draw of water) is equal in intracellular and extracellular fluids.

  • Movement of water through osmosis helps reduce differences in water concentration.

Movement of Ions vs. Water

• Selective Permeability

  • Movement of ions differs from water; occurs selectively due to the selective permeability of the plasma membrane.

  • Some ions may move with water through osmosis or diffusion.

• Passive Processes

  • Osmosis and diffusion are passive processes that do not require energy.

Carrier Mediated Transport

• Transport Mechanism

  • Carrier mediated transport requires energy and is facilitated by proteins.

  • Plays a vital role in processes such as muscle contraction and signaling in the nervous system.

Hormonal Regulation of Water Balance

• Long-term Fluid Balance Communication

  • Maintaining fluid balance is a long-term strategy controlled by hormones.

  • Important hormones:

    • Antidiuretic hormone (ADH)

    • Aldosterone

    • Natriuretic peptides (ANP and BNP)

• Hormone Functions

  • ADH and Aldosterone: Reduce water loss and decrease membrane permeability to water.

  • ANP and BNP: Increase permeability leading to water loss.

Daily Water Intake and Loss

• Fluid Intake Recommendations

  • Estimated daily intake: approximately 2.5 liters, varying by individual needs and circumstances (e.g., activity level, environmental conditions).

• Fluid Loss Mechanisms

  • Water loss occurs via:

    • Urine production

    • Sweating (evaporation from skin)

    • Loss in feces

    • Evaporation from lungs (around 400 mL/day needed for moist alveolar gas exchange).

Summary of Fluid Management

• Maintaining balance in water through osmosis impacts all compartments of the body.

• Water intake comes from food and beverages, and minimal amounts are produced through metabolism.