Which of the following best describes the role of surfactant?

Surfactant plays a critical role in the respiratory system, particularly in the alveoli, which are the tiny air sacs where gas exchange occurs. The primary function of surfactant is to reduce surface tension at the air-liquid interface within the alveoli. By doing so, it prevents the alveoli from collapsing, particularly during exhalation when the volume of air in the lungs is reduced. This stabilization of the alveoli allows for better inflation during inhalation and facilitates effective gas exchange by keeping the alveoli open, ensuring that there is a maximal surface area available for oxygen and carbon dioxide exchange.

This function is essential for maintaining optimal lung function and overall respiratory health. A deficiency of surfactant can lead to conditions such as neonatal respiratory distress syndrome in premature infants, highlighting its importance in maintaining lung integrity.

The other options do not accurately reflect the primary function of surfactant. While oxygen transport and respiratory rate are important aspects of respiratory physiology, they are not directly influenced by surfactant. Additionally, surfactant actually plays a vital role in protecting the lungs from infections by enhancing lung mechanics, rather than increasing the risk of infections.