The number of cells in the human body is about 100.000.000.000.000 (100 trillion , or 10to 14). Most of them short-lived (1-2 days) are cells of the intestinal epithelium. Daily kill nearly 70 billion of these cells. Examples of other short-lived cells are red blood cells - their daily kill nearly 2 billion. However, there are some cells (e.g. neurons, the cells of skeletal muscle fibres), the lifetime of which corresponds to the life of the organism.
Interestingly, when we are born in the brain already has about 14 billion cells. And this number is not incremented until his death. Moreover, once the person turns 25 years, every day there is a reduction in the number of brain cells per 100 thousand.
