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Friday, November 6, 2009

Body’s Cells

The Body’s Cells

Cells are the body’s building blocks. It takes billions of these tiny living units to make just one body. Each cell contains the information needed to build and operate the human body. Although different types of cells have their own shape, size, and job, all share the same basic structure.

A living cell is made up of a thin outer membrane, or skin, that surrounds a watery gel called cytoplasm. All the other minute cell parts float in the cytoplasm. The control center of the cell is called the nucleus. The nucleus contains the information needed to keep a cell alive and working properly.

Every day the body makes billions of new cells by a process called cell division. Some new cells are needed to replace old, worn-out ones. Others make the body grow. Cell division takes place in three main stages.

Each type of cell has its own shape and size, depending on what job it does. Cells are so tiny that you can only see them by using a microscope. A microscope magnifies the


Bone marrow cells do not last very long they divide just hours after they are made. But many nerve cells can last a whole lifetime.

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