Our brain is the most complex organ in the body. This 1.3kg control and command centre contains more than 80 billion neurones, which facilitate every action, every feeling and every thought in our bodies. Brain contains also blood vessels and capillaries, which provide brain cells with the oxygenated and rich blood they need in order to thrive. There are also hormones, neurotransmitters (dopamine, serotonin etc) that help pass neural messages from cell to cell. Photo source: