Structure of the Body and How it Works
The human body may be analysed in terms of its formation – the materials of which it is constructed – and its functions and the systems which perform them. The body is constructed from billions of cells. Cells are capable of performing the definitive functions of all living matter: assimilation of nourishment taken in by the body; growth and repair; reproduction; and excretion of waste products. Cells are of different types, adapted to specialist functions according to the tissues to which they belong. There are five main types of tissue: epithelial; connective; muscular; nervous; and blood tissues. Neoplasms are clusters of abnormal cells. The death of tissue cells, from injury or infection, may lead to death of part of the body. This is prevented by regeneration by mitosis or by fibrosis. Neoplasms are clusters of abnormal cells.