*The PCO2 in the capillaries is higher than that in the alveoli, thus CO2 diffuses into the alveoli, where it is [[Ventilation - Anatomy & Physiology#Exhalation|exhaled]]. | *The PCO2 in the capillaries is higher than that in the alveoli, thus CO2 diffuses into the alveoli, where it is [[Ventilation - Anatomy & Physiology#Exhalation|exhaled]]. |