MCQ Detailed View

People who live at high altitudes, such as in mountainous regions, usually have a larger number of red blood cells (RBCs). This adaptation helps their bodies cope with the lower oxygen levels found at high elevations.

At sea level, the air contains more oxygen compared to areas located high above sea level. As altitude increases, the atmospheric pressure drops, resulting in thinner air and less available oxygen. The human body senses this reduced oxygen availability, and over time, it responds by increasing the production of red blood cells.

Red blood cells play a vital role in the circulatory system. They contain hemoglobin — a protein that binds with oxygen in the lungs and delivers it to tissues and organs throughout the body. When oxygen levels are low, the body produces a hormone called erythropoietin (EPO). This hormone is released by the kidneys and signals the bone marrow to produce more red blood cells. This biological response increases the blood’s capacity to carry oxygen, helping people breathe more efficiently even in low-oxygen environments.

This process is called acclimatization, and it is one of the body’s natural mechanisms for adjusting to environmental changes. It is especially important for people who are born and raised at high altitudes, such as those living in the Himalayas, Andes, or Rocky Mountains. These individuals tend to have higher hemoglobin concentrations and more red blood cells compared to those living at sea level.

The correct answer is: A larger number of Red Blood Cells.

This is a perfect example of how the human body adapts to challenging conditions using physiological changes. Understanding this concept is essential in biology and everyday science, especially when studying the human respiratory and circulatory systems.