Physiological cell regeneration

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As physiological cell regeneration replacement is called dead biological cells with new ones. The ratio of newly emerging cells to perishing cells varies in the organism over time. The renewal rate is between two days for the small intestine and eight years for fat cells. In young individuals, the formation of new cells dominates over the breakdown of old ones. The result is growth and differentiation of new organ and tissue systems. In the adult organism, the relationship shifts towards a finely adjusted balance between newly emerging and dying cells.

There are three different forms of regeneration:

• One-time regeneration is the replacement of the deciduous teeth .
• Cyclic regeneration occurs in the case of the menstrual cycle . The uterine mucous membrane is renewed monthly through hormonal control .
• Most cell types have permanent regeneration. In the intestinal epithelium , cells (lifespan approx. One week) are continuously released into the lumen , where they are digested and resorbed. Red blood cells ( erythrocytes ) are completely replaced within an average of 120 days. The skin is also constantly being replaced by new cells.

The starting point for cell proliferation is usually stem cells , which are undifferentiated cell forms with low division rates. Only the daughter cells that emerge show increased mitotic activity and develop into specific cell types (epithelial cells, skeletal muscle cells, sperm cells ...) in the course of their divisions. In the case of the intestinal epithelium, the stem cells are referred to as crypt cells , in the case of epithelia generally as basal cells , and the skeletal muscles are satellite cells . The stem cells of actively dividing tissues ( spermatogonia in the testicular tubule ) are particularly sensitive to ionizing radiation , which has a damaging effect on the DNA of the cells. With prolonged exposure, this leads to a loss of function of the tissue ( infertility ).

Individual evidence

1. ↑ focus.de: Every few years the body renews itself , January 26, 2016, accessed November 27, 2018