Tidal volume refers to the amount of air that is inspired and expired during each respiration. Normal tidal volume are 400 mL in women and 500 mL in men. As such, tidal volume is affected by gender, age, geographic altitude, the weight and height of the affected person, the degree of physical activity that the person engages in, and the person's ethnicity. If tidal volume increases, this has an inverse effect on the respiratory rate, and vice versa. The only difference between the triplets is their level of physical activity. Jim, due to doing yoga, would be breathing slowly and deeply, leading to his tidal volume being high and the resulting respiratory rate being low. The same, or similar, would be true for Mike, as his respirations would not be rushed, which would also mean that his tidal volume would be considered to be within the normal range. Finally, Bob is experiencing anxiety, which means that his respirations would be fast, leading to a low corresponding tidal volume. Respirations, in terms of how fast they occur and how deep the breaths, is something that is regulated by the medulla oblongata.