What is the typical duration of a single inspiration in normal respiration?

• A. 1 second
• B. 2 seconds
• C. 3 seconds
• D. 4 seconds

Answer: (B)

In normal respiration, a single inspiration typically lasts around 2 seconds. This duration can vary depending on several factors, such as the rate of breathing, the individual’s level of physical activity, and specific physiological needs, but generally, a normal respiratory rate for adults is about 12 to 20 breaths per minute. This translates to an average of 3 to 5 seconds per complete respiratory cycle (inspiration and expiration), which means that each phase of inspiration is commonly noted to be shorter, generally around 1 to 2 seconds.

While the other options suggest different lengths for inspiration, the 2-second duration aligns well with the physiological norms for adult breathing patterns at rest, where the body maintains efficient gas exchange and meets metabolic demands with a balanced rhythm of inhalation and exhalation.