Final answer:
The normal respiratory rate for an adult ranges from 12 to 20 breaths per minute, adjusting as humans transition from infancy through adolescence to ensure efficient gas exchange and alveolar ventilation.
Step-by-step explanation:
The normal respiratory rate for an adult should range from 12 to 20 breaths per minute. This rate can vary depending on numerous factors, including age, physical activity, and overall health. For instance, a child under 1 year old has a faster respiratory rate, ranging from 30 to 60 breaths per minute. As children grow older, this rate decreases, and by about 10 years old, it is closer to 18 to 30 breaths per minute. By adolescence, the respiratory rate settles to a rate similar to that of adults, which is around 12 to 18 breaths per minute, ensuring efficient alveolar ventilation and proper exchange of oxygen and carbon dioxide in the body.