Common carotid artery pharynx. Lateral to the artery, inside the carotid sheath with the common carotid, are the internal jugular vein and vagus nerve. At the lower part of the neck, on the right side of the body, the right recurrent laryngeal nerve crosses obliquely behind the artery; the right internal jugular vein diverges from the artery. On the left side, however, the left internal jugular vein approaches and often overlaps the lower part of the artery. Behind the angle of bifurcation of the common carotid artery is a reddish-brown oval body known as the carotid body. It is similar in structure to
Human body and about 23 litres of fluid inside cells. The content, acidity and composition of the water inside and outside cells is carefully maintained. The main electrolytes in body water outside cells are sodium and chloride, whereas within cells it is potassium and other phosphates. The body contains trillions of cells, the fundamental unit of life. At maturity, there are roughly 30–37 trillion cells in the body, an estimate arrived at by totalling the cell numbers of all the organs of the body and cell types. The body is also host to about the same number of non-human cells as well