What Happens to Red Blood Cells in Distilled Water?

What happens to a human red blood cell when it is placed in distilled water?

• A. It shrivels up
• B. It neither shrinks nor swells
• C. It takes up more salts to balance concentrations
• D. It swells to a larger size

Answer: (D)

When a human red blood cell is placed in distilled water, it undergoes a process called osmosis. Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In the case of distilled water, the concentration of solutes (such as salts) outside the red blood cell is lower than that inside the cell. As a result, water moves into the red blood cell to equalize the solute concentrations on both sides of the cell membrane. This influx of water causes the cell to swell. If enough water enters, the cell can ultimately burst, a phenomenon known as hemolysis. Thus, the correct answer reflects that the red blood cell swells to a larger size due to the absorption of water in an environment where it is exposed to a dilute solution. The other choices describe different scenarios. Shriveled cells would indicate the loss of water, which occurs in hypertonic solutions, while neither shrinking nor swelling would be the case in isotonic solutions. Taking up salts to balance concentrations does not accurately describe what is happening; instead, the focus is on the movement of water rather than salt.

When you think about red blood cells, what comes to mind? Those tiny, disc-shaped cells are pretty remarkable, especially when it comes to understanding how they interact with their environment. Let's dive into what happens when these cells are placed in distilled water—a classic experiment in biology that illustrates the principles of osmosis and cell behavior.

First off, it’s essential to know that red blood cells are surrounded by a semipermeable membrane. This means that while certain materials can pass through freely, others are restricted. When red blood cells are placed in distilled water, they encounter a situation that’s different from what they typically experience in the human body. Now, distilled water has almost no solute content compared to what’s found inside the cells, where salts and other substances are stored. So, what happens next?

Here’s the thing: Water tends to move from areas of low solute concentration to areas of high solute concentration—this is osmosis. In our scenario, because the concentration of solutes inside the red blood cell is higher than that of the distilled water around it, water rushes in. Can you picture that? It’s like a sponge soaking up water! As a result of this influx, the red blood cell swells. If too much water enters, it can eventually burst—a scenario we call hemolysis. Isn’t that a bit dramatic?

But how about the other options? If the cell shrivels up, that indicates it’s losing water, which happens in a hypertonic solution—you might recall that from your classes. Similarly, if there’s neither swelling nor shrinking, that would reflect an isotonic solution, where concentrations of solutes are balanced. And that business of the cell taking up more salts to fix concentration levels? Well, that doesn’t quite capture how osmosis works since the focus here is primarily on water movement, not salt.

It’s these fundamental interactions that play a crucial role in various biological processes, and understanding them can be a game changer in fields like nursing and medicine. You know what else is fascinating? This concept of osmosis isn’t limited to red blood cells; it applies to many other cells in the body too. The dynamics of how cells respond to their environments is a big piece of the puzzle we call life.

As you prepare for the National League for Nursing (NLN) Science Exam, grasping these basic concepts of cell biology can help reinforce your understanding of more complex physiological processes. So, remember: when red blood cells meet distilled water, they swell, and the science of osmosis helps explain why. Keep that in mind as you navigate your studies.