What cell does what?

Answer 1

The cell is the building block that makes up living things. Everything that is alive is made of one or more cells. The simplest plants and animals consist of only one cell. Cells in more complicated living things work together. They are organized in groups, each other which has some special work to do for the plant or animal.

A tissue is a group of cells of a particular kind that does one particular type of work. For example, there is bone tissue, muscle tissue, or bark tissue. When tissues co-operate to perform a special task, such a group of tissues is called an "organ". An example of this is the human hand, which is composed of bone, muscle, nerve, and other tissues.

In the human body there are five important types of cells. Epithelial cells make up the skin and the glands, and line the blood vessels. Muscle cells make up the three kinds of muscles. Nerve cells make up the brain, spinal cord, and nerves. Blood cells are found in the blood and lymph. Connective tissue cells make up the framework tissue of the body.

The circulatory system, in higher forms of living, carries food and oxygen to every cell and removes waste products, like carbon dioxide. The individual cells combine the food and oxygen slowly, thus obtaining the heat and energy necessary for their life and work. It is because of this energy that muscles can contract, nerves can conduct messages, and the brain can think.