Which of the following is not a function of the respiratory system?

The respiratory system is primarily responsible for the exchange of gases—oxygen and carbon dioxide—between the body and the environment, which is a critical function for maintaining cellular respiration and supporting life. Voice production is another important function, enabled by the larynx, which houses the vocal cords, allowing for the creation of sound through the passage of air. Furthermore, the respiratory system contributes to filtering the air we breathe, using structures like nasal hairs and mucus to trap particles and pathogens.

Nutrient absorption, however, is not a function of the respiratory system. This process primarily occurs in the digestive system, where nutrients from ingested food are broken down and absorbed into the bloodstream through the lining of the intestines. Given this context, identifying nutrient absorption as unrelated to the respiratory system highlights the distinct roles of different body systems in maintaining overall health and functionality.