Termination of cell life due to external and internal causes is called death. Millions of cells die in the human body every day. Cell death occurs in two ways. Necrosis and apoptosis.
1. Necrosis: Cell death due to lack of nutrients or toxic substances is called necrosis. Deficiency of one or more of the micronutrients and macronutrients can cause cell death. Toxins enter the body in various ways, chemical reactions produce toxins, and excess drugs accumulate as toxins. These toxins can cause cell death.
2. Apoptosis: Apoptosis is genetically controlled death. In this process, unnecessary body cells or organs die. Apoptosis is the destruction or death of tissue between human fingers. Apoptosis causes red blood cells, white blood cells and platelets to die after a certain period of time. If these cells survive for a long time, they can become cancer. The role of apoptosis in human body is-
(i) Finger differentiation during embryonic development is by apoptosis.
(ii) Dorsal neural tube closure due to apoptosis.
(iii) Remnants of dying organelles (pro-nephrons) are removed from the body by apoptosis.
(iv) Wolffian ducts are removed by apoptosis during embryonic sex determination.
(v) Residual tissue between the umbilical cord and the sac is removed by apoptosis during embryonic development.