Human iron metabolism energy as ATP from a multi-step process known as cellular respiration, more specifically from oxidative phosphorylation at the mitochondrial cristae. Iron is present in the iron-sulfur clusters and heme groups of the electron transport chain proteins that generate a proton gradient that allows ATP synthase to synthesize ATP (chemiosmosis). Heme groups are part of hemoglobin, a protein found in red blood cells that serves to transport oxygen from the lungs to the tissues. Heme groups are also present in myoglobin to store and diffuse oxygen in muscle cells. The human body needs iron for oxygen transport. Oxygen (O) is required
Blood the presence of potential molecular fibers in the form of fibrinogen. Blood performs many important functions within the body, including: Blood accounts for 7% of the human body weight, with an average density around 1060 kg/m, very close to pure water's density of 1000 kg/m. The average adult has a blood volume of roughly , which is composed of plasma and several kinds of cells. These blood cells (which are also called corpuscles or "formed elements") consist of erythrocytes (red blood cells, RBCs), leukocytes (white blood cells), and thrombocytes (platelets). By volume, the red blood cells constitute about 45% of