Which system is primarily responsible for gas exchange in the body?

Which system is primarily responsible for gas exchange in the body?

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

Answer: (B)

Gas exchange happens when oxygen from the air moves into the blood and carbon dioxide moves from the blood into the air to be exhaled. This diffusion occurs across the thin walls of the alveoli in the lungs, which provide a large surface area and a moist environment for efficient transfer. The driving force is the partial pressure gradient: oxygen is higher in the alveolar air than in the blood, while carbon dioxide is higher in the blood than in the alveolar air. The respiratory system provides the sites for this exchange, while the circulatory system mainly transports gases to and from tissues; the digestive and endocrine systems don’t participate directly in gas exchange.

Gas exchange happens when oxygen from the air moves into the blood and carbon dioxide moves from the blood into the air to be exhaled. This diffusion occurs across the thin walls of the alveoli in the lungs, which provide a large surface area and a moist environment for efficient transfer. The driving force is the partial pressure gradient: oxygen is higher in the alveolar air than in the blood, while carbon dioxide is higher in the blood than in the alveolar air. The respiratory system provides the sites for this exchange, while the circulatory system mainly transports gases to and from tissues; the digestive and endocrine systems don’t participate directly in gas exchange.