Which chamber has the job of pumping blood from the heart to the brain

The answer is the left ventricle.

The blood is first transported from the lungs into the left atrium. These blood are oxygenated and full of nutrients since it just got out from the lungs from gas exchange.
Then, the blood is transferred down to the left ventricle, the largest chamber. They first have to pass the bicuspid valves.

Then, semiluna valves opens and the blood from the left ventricle get pump out of the heart through the artery. These blood get pumped to all other organs except lungs.

Therefore, brain is an organ that the left ventricle pumps blood to.

Pe.dometer would be the most useful to you for monitoring heart rate.