Osmosis and Its Effects on Animal Cells

Overview of Osmosis

• Osmosis is the movement of water molecules from an area of higher to lower water potential.
• Water potential is influenced by the presence of solutes; pure water has a potential of 0 kPa.
• Cytoplasm of animal cells contains various solutes (e.g., glucose, salts, amino acids), leading to a negative water potential.

Water Potential in Animal Cells

• Example: Water potential of an animal cell = -300 kPa.
• Important: Different cells have different water potentials.

Effects of Different Solutions on Animal Cells

Distilled Water (0 kPa)

• Animal cells immersed in distilled water have a more negative water potential.
• Water moves into the cell, increasing internal pressure, potentially causing the cell to burst.
• Important: Distilled water should not be injected into veins as it can cause cells to burst.
• Drinking distilled water is usually safe due to body's regulation of water absorption.

Concentrated Salt Solution (-700 kPa)

• Water potential outside is more negative than inside the cell.
• Water moves out, causing cells to shrink, potentially leading to cell death.
• Essential for survival: Cells require water for chemical reactions (e.g., hydrolysis).

Dilute Salt Solution (equal to -300 kPa)

• Water potential inside and outside the cell is equal.
• No net movement of water; cell remains unchanged in volume.
• Water still moves in and out at equal rates.

Medical Implications of Osmosis

Dehydration Treatment

• Dehydrated patients cannot be given pure or distilled water intravenously.
• Pure water could cause cell swelling or bursting due to osmosis.

Normal Saline Solution

• 0.9% sodium chloride solution (normal saline) has a water potential equal to cytoplasm.
• Prevents damage to cells during intravenous therapy.
• Used to rehydrate without causing cell damage.

Conclusion

• Understanding osmosis is crucial in medical treatments to avoid cell damage.
• Use of saline solutions is critical in managing dehydration safely.