Sexercise levels increase, which of the following physiological changes occurs in the respiratory system?

a. the respiratory muscles shrink.

b. the lungs expand in size.

c. the trachea widens.

d. the airways narrow.

The physician ordered velosef (cephradine) im 50 mg/kg/day in equally divided doses four times a day for a child who weighs 40 pounds. convert pounds to kilograms and then calculate the prescribed dosage. mg every hours