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Understanding Cancer Series-Part5 (Example of Normal Growth)

Discussion in 'Oncology' started by waleed, Sep 15, 2011.

  1. waleed

    waleed Moderator

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    How does the body grow and maintain itself?

    The body is made up of tiny cells - for example, skin cells, muscle cells, heart cells, nerve cells, and bone cells. When a baby grows, the number of cells increases very quickly. A cell becomes a bit larger, then divides into 2 "daughter" cells . After a period of time, each of these cells divides, and so on.
    Normal cell division.: A cell grows a bit larger then divides into 2 cells.

    Once a child grows to adulthood, the size of the body no longer increases. However, our bodies go through a lot of wear and tear, both inside and outside. Worn-out cells constantly need to be replaced, so cell division still takes place, but more slowly. An obvious "outside" change is the tiny bits of dead skin flaking off as the skin constantly renews itself.

    Although our bodies' cells continue to divide to replace worn-out cells, this happens in a very ordered, systematic way. The reason is that each cell carries genetic instructions that regulate how fast the cell should grow and divide and when the cell should die. A balance between cells growing and dying keeps our bodies functioning normally.

    To illustrate what is meant by( normal growth control), consider the skin. The thin outermost layer of normal skin, called the epidermis, is roughly a dozen cells thick. Cells in the bottom row of this layer, called the basal layer, divide just fast enough to replenish cells that are continually being shed from the surface of the skin. Each time one of these basal cells divides, it produces two cells. One remains in the basal layer and retains the capacity to divide. The other migrates out of the basal layer and loses the capacity to divide. The number of dividing cells in the basal layer, therefore, stays the same.
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    source 1:Breast Cancer - Symptoms & Signs, Causes, Diagnosis & Treatment - C-Health
    source 2:Comprehensive Cancer Information - National Cancer Institute
     

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