The process in which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one is called:

1. A

   tubular reabsorption

2. B

   tubular secretion

3. C

   osmosis

4. D

   filtration

Appeared in: NHM UP Staff Nurse-2023 Shift-2nd

Explanation

• Osmosis is the specific term for the passive movement of a solvent, like water, across a semipermeable membrane.
• The driving force for this movement is the difference in solute concentration between the two sides of the membrane.
• Water moves from an area of lower solute concentration (higher water potential) to an area of higher solute concentration (lower water potential) to achieve equilibrium.
• This process is fundamental to maintaining fluid balance across all body compartments and does not require metabolic energy (ATP).

Why Other Options Were Wrong

• Option A: Tubular reabsorption is a broader physiological process occurring in the kidneys, not the fundamental physical principle of solvent movement. It involves multiple transport mechanisms, including osmosis, diffusion, and active transport, to move substances from the filtrate back into the blood.
• Option B: Tubular secretion is the opposite of reabsorption. It is an active process that moves waste products and excess substances from the blood into the kidney tubules for excretion. It does not describe solvent movement from a less to a more concentrated solution.
• Option D: Filtration is the movement of fluid and solutes across a membrane driven by hydrostatic pressure (a physical 'pushing' force), not by a solute concentration gradient. The direction of movement is from high pressure to low pressure.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Principles of Cellular Transport as background academic context rather than a clinical decision trigger.
• Understanding osmosis is critical for administering IV fluids. Isotonic solutions (e.g., 0.9% NaCl) don't cause a net fluid shift. Hypotonic solutions cause fluid to move into cells, potentially leading to cell lysis. Hypertonic solutions pull fluid out of cells, causing them to shrink (crenate).
• Osmosis governs fluid shifts in conditions like edema, where fluid moves from the intravascular space to the interstitial space, and in dehydration, where fluid moves from cells into the bloodstream to compensate for fluid loss.
• What if? If a patient with severe dehydration and cellular shrinkage is given a hypotonic IV solution (e.g., 0.45% NaCl)? This would be a correct therapeutic action. The hypotonic fluid would lower the osmolality of the ECF, causing water to move via osmosis back into the dehydrated cells, rehydrating them.

How to Approach the Question

• This is a definition-based recall question.
• First, break down the definition provided in the question stem: 1) movement of a solvent, 2) across a semipermeable membrane, 3) from a less concentrated solution, 4) to a more concentrated solution.
• Recognize that this is the classic scientific definition of a specific physical process.
• Evaluate each option against this definition.
• Osmosis directly matches all components of the definition.
• Rule out the other options by identifying their key characteristics: 'Filtration' is pressure-driven, while 'tubular reabsorption' and 'tubular secretion' are complex, multi-step physiological processes specific to the kidney, not the fundamental principle of solvent movement itself.

Concept Tested & Keywords

• Concept Tested: Principles of Cellular Transport
• Stem keywords: solvent, semipermeable membrane, less concentrated solution, more concentrated solution
• Lead-in keywords: is called

Question ID

Qn7z1fSlJ1Zv9bn0t5ssWz

Copy ID

Reference Book

E6 Physiology Ganong 27e Vol 1 Part 1 p. 15-17

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 47-49

E6 Nursing Fundamentals Taylor p. 775-777