Final answer:
Hypovolemia is the term that indicates a low or decreased blood volume, which can be caused by bleeding, dehydration, and other factors, and is treated with intravenous fluids.
Step-by-step explanation:
The term that indicates low or decreased blood volume is hypovolemia. This condition may arise due to various causes such as bleeding, dehydration, vomiting, severe burns, or the use of some medications for treating hypertension. It's vital to note that the body's regulatory systems are usually so effective at maintaining blood pressure that a person might not show symptoms until there is a significant loss of blood volume, in the range of 10-20%. When hypovolemia occurs, treatment often involves the administration of intravenous fluids to restore the lost volume.