What is the difference between tidal volume and vital capacity?

Tidal volume refers to the amount of air inhaled or exhaled during normal breathing, while vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inhalation.

Tidal volume and vital capacity are both measurements used in respiratory physiology, but they refer to different aspects of lung function. Tidal volume is the volume of air that is inhaled or exhaled during a normal, resting breath. This is typically around 500 millilitres in a healthy adult. It's a measure of the regular, everyday function of the lungs and can change based on factors like exercise, sleep, or illness.

Vital capacity, on the other hand, is a measure of the maximum amount of air a person can expel from their lungs after taking the deepest breath they can. This includes the tidal volume, the inspiratory reserve volume (the maximum amount of air a person can inhale over and above a normal breath), and the expiratory reserve volume (the maximum amount of air a person can exhale beyond a normal breath). In a healthy adult, the vital capacity is typically between 3 and 5 litres. It's a measure of the lungs' maximum capacity and can be affected by factors like age, sex, height, and disease.

IB Biology Tutor Summary: Tidal volume is the air moved in or out during normal breaths, usually about 500 ml. Vital capacity is the total air expelled after the deepest inhalation, generally between 3 to 5 litres. Tidal volume shows everyday lung function, while vital capacity indicates the lungs' maximum capacity, influenced by factors like age and health.