What are the functions for the human circulatory system?

Answer 1

1: Carrying nutrients to the cells

2: Carrying wastes away from the cells

3: Carrying chemical messangers from one part of the body to another

4: Distributing heat throughout the body

5: Maintaining acceptable levels of body fluid (with help from the kidneys)

6: Defending against invading organisms (to some degree)

Answer 2

Firstly it provides oxygen and glucose to your brain. This is the main function. Also, the blood circulation maintains the pumping of your heart, which is so important as the first one. And finally, the blood circulation carry nutrients to all cells of your organism. Trillions of cells.

Summarising, it keeps you alive.