The circulatory system transports nutrients, oxygen, carbon dioxide, hormones, and blood cells throughout the body. It consists of the heart, blood, and blood vessels. The heart pumps oxygenated blood received from the lungs to the body through the systemic circulation and deoxygenated blood to the lungs through the pulmonary circulation. Blood is made up of plasma, red blood cells, white blood cells, and platelets. Red blood cells contain hemoglobin which transports 98.5% of oxygen in arterial blood while the remaining 1.5% is dissolved in plasma.