Final answer:
The term for a low ventilatory rate leading to elevated arterial PCO2 is hypoventilation, which can result in hypercapnia. Hyperventilation, on the other hand, leads to low CO2 levels and a high blood pH (respiratory alkalosis). The respiratory rate and volume will decrease in hypoventilation and increase in hyperventilation.
Step-by-step explanation:
The term that describes a ventilatory rate which is too low, leading to potentially elevated arterial PCO2, is hypoventilation. When alveolar ventilation is too low, there is insufficient air movement in and out of the lungs, causing an increase in arterial PCO2, which can lead to hypercapnia. Hypercapnia is a condition characterized by abnormally elevated blood levels of CO2, which can occur due to impaired respiratory functions or reduced breathing. In contrast, hyperventilation is an increased ventilation rate that exceeds the body's requirement for oxygen, causing abnormally low blood carbon dioxide levels and a high blood pH, a state known as respiratory alkalosis.
In terms of changes in respiratory rate and volume, if alveolar ventilation is too low (hypoventilation), the respiratory rate will decrease and the volume of air per breath is also likely to decrease. If alveolar ventilation is high (hyperventilation), the respiratory rate will increase, and the volume of air per breath might decrease as the body attempts to expel excessive CO2 to bring levels back to normal.