Apoptosis is programmed cell death that results in the cell being broken down into small molecules and removed. There are signaling pathways in the cell that causes activation of suicide proteins that start the process of apoptosis. This is important in the normal growth and development of new cells so that they are not damaged by the contents of the old or damaged cell.
Signaling pathways cause a receptor cell to bind to the damaged cell. The signals can come from outside the cell such as the death-signaling cell, or from inside the cell in the mitochondria, the nucleus, or the endoplasmic reticulum. The enzymes released from inside the cell destroy the DNA, organelles, and other components of the cytoplasm and shrink them. This is also known as blebbing. The parts are ingested and digested by phagocytes leaving nothing behind. Apoptosis occurs when a cell has been damaged by disease or illness or when the cell has reached the end of its life cycle.
Insufficient apoptosis can cause cells to continue to divide even though they are damaged or not functioning appropriately and should have been destroyed. The cells may start to divide when there is no need for them too, causing an overgrowth. The overgrowth of cells can cause tumors to form that can be benign or malignant. If the cells lose their ability to divide for specialized areas they can continue to divide and cause cancerous cells to travel through the bloodstream to various places in the body. This is called metastasis. A cancer cell can bypass apoptosis even though it is damaged. This is one reason why cancer cells can remain living when other cells would have died. Apoptosis can occur too often as well. This is the case in Alzheimer’s and Parkinson’s disease. Alzheimer’s disease results from neurons dying in the hippocampus and cerebral cortex areas. This causes shrinking of the brain tissue. Parkinson’s disease is caused by neurons dying in the...