Question

Explain the following with the help of Henry’s law : (i) Bends (ii) Anoxia

Hint:

To prevent bends, modern scuba tanks use air diluted with Helium. Helium is used because it has very low solubility in blood even at high pressures.

Answer 1

Concept:

• Henry’s Law states that at a constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid.

• Mathematically: \( P = K_{H} \cdot \chi \), where \( P \) is the partial pressure and \( \chi \) is the mole fraction of the gas in the solution.

• Pressure changes significantly affect how much gas our blood can hold.
Step 1: Explain the physiology of "Bends"
Scuba divers breathe air at high pressure while deep underwater. According to Henry's Law, this high pressure increases the solubility of atmospheric gases, particularly Nitrogen (\( N_{2} \)), in the blood and tissues.
When the diver ascends rapidly to the surface, the external pressure decreases. This causes the dissolved Nitrogen to quickly lose its solubility and come out of the blood in the form of bubbles. These bubbles block capillaries and pinch nerve endings, causing a painful and life-threatening condition called "the bends."

Step 2: Explain the physiology of "Anoxia"
At high altitudes, such as on mountain peaks, the partial pressure of oxygen is much lower than at sea level.
By Henry's Law, lower partial pressure leads to a decrease in the solubility of oxygen in the blood of climbers. This results in low concentrations of oxygen in the blood and tissues, causing climbers to feel weak and have difficulty thinking clearly. This condition is medically termed Anoxia. The final answer is (i) Bends: Nitrogen bubble formation; (ii) Anoxia: Low oxygen solubility.