Which body system is tasked with supplying oxygen to the blood and eliminating carbon dioxide?

• A. Endocrine system
• B. Circulatory system
• C. Respiratory system
• D. Digestive system

Answer: (C)

The respiratory system is primarily responsible for the process of gas exchange, which involves supplying oxygen to the blood and eliminating carbon dioxide from it. This system includes the nasal passages, throat, and lungs, where oxygen is inhaled into the alveoli in the lungs. Here, oxygen diffuses from the air into the bloodstream, where it binds to hemoglobin in red blood cells. At the same time, carbon dioxide, a waste product produced by cellular metabolism, diffuses from the blood into the alveoli to be exhaled. This vital exchange helps maintain the body's acid-base balance and supports cellular respiration, which is essential for producing energy.

Other systems play different roles in the body: the endocrine system regulates hormones and metabolic processes, the circulatory system distributes oxygen and nutrients throughout the body via the blood, and the digestive system processes food and absorbs nutrients. While there is some overlap in functions, the specific task of directly supplying oxygen and removing carbon dioxide is clearly designated to the respiratory system.