Final answer:
Polycythemia is the term for an increase in the number of formed elements of blood due to a decrease in plasma. It can lead to increased blood viscosity and difficulty in blood circulation. It can occur transiently or as a result of certain medical conditions.
Step-by-step explanation:
Polycythemia is the term for an increase in the number of formed elements of blood due to a decrease in plasma. It is characterized by an elevated red blood cell count, which can lead to increased blood viscosity and difficulty in blood circulation. Polycythemia can occur transiently in situations such as dehydration or in conditions like polycythemia vera, a bone marrow disease.