Question

Explain the difference between hypertonic and hypotonic, using human cells as a reference point. (p. 56)

Short answer

Short Answer: Hypertonic solutions have a higher solute concentration compared to the cell, causing water to move out of the cell and leading to cell shrinkage. Hypotonic solutions have a lower solute concentration compared to the cell, causing water to move into the cell and resulting in cell swelling. The movement of water occurs due to osmosis in an effort to equalize the solute concentrations on both sides of the cell membrane.

Step-by-step solution

Define Hypertonic and Hypotonic Solutions

Hypertonic solutions have a higher concentration of solutes (dissolved substances) than the cell, while hypotonic solutions have a lower concentration of solutes compared to the cell. These solutions are relative to the environment surrounding the cell, which affects the movement of water in and out of the cells through a process called osmosis.

Osmosis

Osmosis is the movement of water molecules across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration. This process continues until the concentration of solutes on both sides of the membrane becomes equal, reaching a state called isotonic equilibrium.

Human Cells in Hypertonic Solutions

When human cells are placed in a hypertonic solution, the concentration of solutes outside the cell is higher than that inside the cell. As a result, water will move out of the cell through osmosis, trying to equalize the solute concentration on both sides of the cell membrane. In this process, cells lose water, causing them to shrink and eventually leading to cell damage or death (called crenation).

Human Cells in Hypotonic Solutions

In the case of hypotonic solutions, the concentration of solutes outside the cell is lower than that inside the cell. This causes water to move into the cell through osmosis in an attempt to equalize solute concentration on both sides of the cell membrane. Consequently, cells absorb more water, which leads to swelling and the potential rupture of the cell (called lysis).

Conclusion

In summary, hypertonic solutions cause human cells to shrink, while hypotonic solutions cause them to swell. The key to understanding the difference between these solutions is the behavior of water molecules during osmosis. Maintaining an isotonic environment, where the concentration of solutes inside and outside the cell is equal, prevents potential cell damage due to hypertonic or hypotonic conditions.

Key concepts

Hypertonic Solutions

When we talk about hypertonic solutions in relation to human cells, we're focusing on environments where the outside solution contains more solutes than the fluid inside the cell. Imagine you're adding extra salt to a glass of water where a grape (our cell) is soaking. Here's what happens:

• The area where the grape sits becomes hypertonic compared to the grape itself.
• As a result, water from inside the grape moves out into the saltier solution to try and balance solute concentration, a process called osmosis.

In human cells exposed to hypertonic conditions, the same thing happens. Water exits the cell to dilute the external solution. Sadly, as the water leaves, our cell shrivels, shrinking in size, a phenomenon known as crenation. Over time, if the water loss isn't stopped, the cell could be severely damaged or even die. damage by maintaining an isotonic balance.

Hypotonic Solutions

Hypotonic solutions are the opposite of hypertonic ones—they have a lower concentration of solutes compared to the fluid inside the cell. Picture a grape placed into a plain water bowl. The grape's insides have more solutes compared to the surrounding water, so water begins to enter the grape:

• The outside is hypotonic when compared to the grape's insides.
• The grape swells as water rushes in, aiming to balance the difference in solute concentration.

Human cells in hypotonic solutions undergo a similar process. Water flows into the cell through osmosis, making the cell expand. If too much water accumulates inside, the cell may burst, an event known as lysis. To prevent this, maintaining a balanced, isotonic environment is essential for cell wellbeing.

Isotonic Equilibrium

Achieving isotonic equilibrium means the concentration of solutes is equal inside and outside the cell. This balance is ideal for cells, including our human cells. Think of it as a perfect harmony where neither too much water enters nor exits the cell.

• Water molecules move in and out at an equal rate, keeping the cell's size stable.
• There is no net movement of water as the exchange of molecules is balanced.

In practical terms, isotonic equilibrium is the sweet spot, preventing the adverse effects of both hypertonic and hypotonic environments. For example, medical solutions like IV fluids are carefully made to be isotonic with human blood to ensure patient safety and cellular health. Cells function optimally in this stable state, avoiding damage from excessive swelling or shrinking.