Cells are the basic unit of life; the microscopic building blocks from which the human body as well as the animals, insects and plants are constructed. Even though they are the smallest, they are highly complex.
Every adult body contains more than a hundred million cells, microscopic structures averaging only a hundredth of a millimeter in diameter.
Today, the cell theory guides the work of many biologists and physicians as they study diseases, food production, population control and other problem of living systems.
All living things are made of cells, how large or small the organisms was, it was made of cells. According to scientists found that all things alive were composed of cells, including the tissues, organs of the human body. This was a major step in understanding life. It led to one of the foundation theories of biology. These tiny structures build up the skin, bones, muscles and all internal organs. Cells hold many functions in a human body. It performs both structural and functional role, it has variety of actions that sustain body tissues and organs.
The body cells vary greatly in shape, size, and detailed structure according to the jobs they have to do. Some cells are long and thin, some cells have thin walls and others have thick walls, and some cells are alive and others are dead! Dead cells can be useful to a multi cellular organism. In humans, dead cells contribute the structure of hair shafts and nails. In plants, dead cells provide stony protective layers in peach pits and the conductive elements of the xylem. ...