The human body is made up of an enormous number of tiny units of living materials called cells. The cells are of different kinds and are grouped together to form tissues. These tissues form organisms.
The body works as a whole with each individual cell requiring food and oxygen and having to get rid of waste materials. Each cell is sensitive to any change in its surroundings.
The body of human consists of axial parts of the head, neck and trunk, and two pairs of limbs. He has the skeletal system, moved by muscular system, controlled by nervous system through the impulses received from the organs. All these are covered by the skin.
Man studied cell as early as about 1610. To his belief all organism bodies are composed of essentially smaller part, called cells.
Living substances consists of these elements most abundant it at the surface of the earth. At least about twenty elements have been shown to be essential for life.
Human beings as living organisms are interested in the thing that surround them.
Read about complex mankind !