It enters the kidneys to start the formation of urine. It is taken up by the cells of the surrounding tissues. Blood is an example of connective tissue. Phagocytes in the blood are derived from stem cells in the blood. A heart will stop beating when the nerves to the heart are severed.
Some cardiac cells are self-excitatory.
Cardiac cells are coupled by gap junctions. The pacemaker of the heart is the sinoatrial node. The systemic circuit carries oxygenated blood. Humans have an open circulatory system. The function of the heart is to make the blood flow through the circulatory system.