Final answer:
Bioavailability is the term that measures drug absorption and refers to the total amount of drug in the blood.
Step-by-step explanation:
The term that measures drug absorption and refers to the total amount of drug in the blood is Bioavailability. Bioavailability is a pharmacokinetic parameter that represents the fraction of an administered dose of a drug that reaches systemic circulation unchanged. It takes into account the extent and rate at which a drug is absorbed into the bloodstream, and is often expressed as a percentage or fraction.