Which type of solution causes water to shift from the cells into the plasma?

AIIMS Patna NO - 2020

Applied Physiology

Medium

Appeared in: AIIMS Patna NO - 2020

Explanation

A hypertonic solution has a higher concentration of solutes than the cell's interior.
Due to osmosis, water moves from an area of lower solute concentration (inside the cell) to an area of higher solute concentration (the surrounding solution/plasma).
This outflow of water causes the cell to lose volume and shrink, a process known as crenation.
The image provided visually confirms this, showing the red blood cell shriveling in a hypertonic environment.

Option A: The term 'Alkaline' refers to the pH of a solution (pH greater than 7), not its solute concentration or tonicity. While pH is vital for cellular function, it is not the primary driver of water shifting between cells and plasma in the context of osmosis.
Option B: A hypotonic solution has a lower solute concentration than the cell. This causes the opposite effect: water moves from the solution into the cell, causing it to swell and potentially burst (lysis).
Option C: The term 'Acidic' refers to the pH of a solution (pH less than 7). Similar to 'Alkaline', this describes acid-base status, not the osmotic pressure that governs water movement between compartments.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Tonicity and Osmosis as background academic context rather than a clinical decision trigger.
Hypertonic solutions (e.g., 3% or 5% saline) are used clinically to treat conditions like cerebral edema (swelling of the brain) by drawing excess fluid out of brain cells and into the bloodstream.
When administering hypertonic IV fluids, nurses must monitor patients closely for signs of fluid volume overload in the vascular space (e.g., high blood pressure, pulmonary edema) and cellular dehydration (e.g., confusion, thirst).
What if? If a patient with severe dehydration were given a hypertonic solution, it would worsen their condition by pulling even more water out of their already dehydrated cells, potentially leading to circulatory collapse. Dehydrated patients typically require isotonic or hypotonic solutions.

How to Approach the Question

First, identify the key process in the question: 'water to shift from the cells into the plasma'. This means water is moving OUT of the cells.
Recall the principle of osmosis: water moves from an area of lower solute concentration to an area of higher solute concentration across a semipermeable membrane.
For water to move OUT of a cell, the solution outside the cell (in the plasma) must have a higher solute concentration.
Evaluate the options based on this principle. The term for a solution with a higher solute concentration is 'hypertonic'.
Eliminate 'Acidic' and 'Alkaline' as they relate to pH, not solute concentration (tonicity).
Eliminate 'Hypotonic' as it describes a solution with a lower solute concentration, which would cause water to move INTO the cell.

Concept Tested & Keywords

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