Final answer:
Hypercapnia is the term that describes excessive carbon dioxide in the blood, and it often results from impaired respiratory function or hypoventilation. Hyperventilation leads to hypocapnia and can cause respiratory alkalosis by lowering CO2 levels and increasing blood pH. The correct option is a.
Step-by-step explanation:
The term that describes excessive carbon dioxide in the blood is hypercapnia.
Hypercapnia occurs in conditions that impair respiratory functions, such as pneumonia and congestive heart failure, or due to reduced breathing caused by certain drugs or even holding one's breath.
Hypocapnia, on the other hand, refers to abnormally low blood levels of CO2 and is typically a result of hyperventilation, which is an increased ventilation rate leading to low blood CO2 levels and a high (alkaline) blood pH.
It is important to note that respiratory acidosis occurs when there is an excess of carbonic acid in the blood, making it overly acidic, and this can also be a result of hypercapnia. The correct option is a.