Human circulation has three elements, which are the heart, the blood vessels, and the blood. All together, this is known as the cardiovascular system. Blood, which is composed of fluid plasma, with erythrocytes, leukocytes, and platelets which circulate within the blood, and account for 40% of it. Blood Plasma is a complex solution of water made with metabolites & wastes, salts & ions, and proteins. Metabolites and wastes can be glucose, lipids, vitamins, hormones, …showed first 75 words of 886 total…

…showed last 75 words of 886 total…These arteries carry deoxygenated blood to the lungs, and then the blood is returned to the left side of the heart, where it can be pumped to the rest of the body. Contraction of the heart is started by the periodic spontaneous depolarization of cells of the SA node. The resulting wave of depolarization passes over the left and right atria, causing their muscles to contract. That is how circulation occurs inside the human body.