How does oxygen deliver into the body through the respiratory system?

• A. Through the skin and mucous membranes
• B. Through the blood vessels in the heart
• C. Through the alveoli wrapped in capillaries
• D. Through the muscles of the diaphragm

Answer: (C)

Oxygen delivery into the body occurs primarily through the alveoli, which are tiny air sacs located in the lungs. When you inhale, air enters the respiratory system and travels down the trachea, branching into the bronchi and finally reaching the alveoli. The walls of the alveoli are incredibly thin and are surrounded by a network of capillaries.

In this area, oxygen from the inhaled air diffuses across the alveolar membrane and into the blood within the capillaries due to the concentration gradient; the concentration of oxygen is higher in the alveoli than in the blood. At the same time, carbon dioxide, which is a waste product of metabolism found in higher concentration in the blood, diffuses from the blood into the alveoli to be exhaled.

This exchange process is vital for providing oxygen to the body's cells and removing carbon dioxide, enabling cellular respiration and maintaining the overall function of the body. Therefore, the description of oxygen delivery through the alveoli wrapped in capillaries highlights the crucial role of the respiratory and circulatory systems in gas exchange.