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

JIPMER Nursing Officer-2017

Applied Physiology

Easy

Appeared in: JIPMER Nursing Officer-2017

Explanation

Hypertonic solutions have a higher solute concentration (osmolality) than the fluid inside cells.
This creates an osmotic pressure gradient that pulls water from areas of lower solute concentration (inside the cells) to the area of higher solute concentration (the plasma).
The net movement of water is from the cells into the bloodstream (plasma), causing the cells to shrink (crenate).
This process effectively expands the volume of the plasma at the expense of the intracellular fluid.

Option A: The term 'alkaline' describes the pH of a solution (a pH greater than 7.45), which relates to its acidity or basicity. It does not describe the solution's solute concentration (tonicity) or its effect on fluid movement via osmosis.
Option B: Isotonic solutions have a solute concentration equal to that of the body's cells and plasma. Therefore, they do not create an osmotic gradient, and there is no net movement of water between the cells and the plasma.
Option C: Hypotonic solutions have a lower solute concentration than the body's cells. This causes water to move from the plasma into the cells, leading to cellular swelling and potentially lysis (bursting). This is the opposite of the fluid shift described in the question.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Tonicity of intravenous solutions and the principle of osmosis as background academic context rather than a clinical decision trigger.
Hypertonic solutions, such as 3% or 5% sodium chloride, are used cautiously in critical care settings to treat conditions like severe, symptomatic hyponatremia or cerebral edema. By drawing water out of swollen brain cells, they can help reduce intracranial pressure.
Nurses must administer hypertonic solutions slowly and monitor patients closely for signs of intravascular fluid volume overload, such as a bounding pulse, elevated blood pressure, and pulmonary edema (crackles in the lungs).
What if? If a hypotonic solution were mistakenly given to a patient with cerebral edema, it would worsen the condition. The fluid would shift into the already swollen brain cells, dangerously increasing intracranial pressure.

How to Approach the Question

First, identify the core concept of the question, which is the movement of water between body compartments (cells and plasma). This points to the principles of osmosis and tonicity.
Recall the definitions of the different types of tonicity: Isotonic (same concentration as cells), Hypotonic (lower concentration), and Hypertonic (higher concentration).
Apply the fundamental rule of osmosis: water always moves from an area of lower solute concentration to an area of higher solute concentration.
Analyze the specific fluid shift required by the question: 'from cells to plasma'. This means water needs to move OUT of the cells.
Deduce which condition would cause this shift. For water to leave the cells, the solution in the plasma must have a higher solute concentration. This is the definition of a hypertonic solution.
Systematically eliminate the other options. 'Alkaline' relates to pH, not tonicity. 'Isotonic' causes no net shift. 'Hypotonic' causes the opposite shift (into cells).

Concept Tested & Keywords

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