Cell injury
Cell injury is a variety of stress changes that damage a cell due to external and internal environmental changes. Which can lead to cell death.
Cell death usually occurs in 2 processes.
1. Apoptosis
2. Necrosis.
Apoptosis is a form of programmed cell death that occurs in multicellular organisms. Changes in various biochemical substances can lead to cell changes and death. These changes include bleaching, cell contraction, nuclear fragmentation, chromatin condensation, DNA fragmentation and mRNA decay.
On the other hand, Necrosis is the death of a limited area of plant or animal tissue as a result of disease or injury. It is a cause of premature tissue death, as opposed to spontaneous natural death. It can be caused by both physical and biological injuries. Examples of physical injuries include cuts, burns, wounds, lack of oxygen (anoxia) and hyperthermia. Immunological attacks and the effects of pathogenic agents in biological trauma.
One of the most common causes of injury is lack of oxygen or hypoxia; In fact, it is the biggest cause of cell injury. When our cardiac or respiratory system does not work properly, there is a lack of oxygen in the blood. This is called hypoxia. This means that our red blood cells cannot properly transport oxygen to all cells. As a result of which the cells die. Then various diseases due to lack of oxygen occur. Such as anemia or carbon monoxide [CO] toxicosis
Physical agent
Physical factors for cell injury include mechanical injury, extreme temperature, radiation, and electric shock. Trauma can directly damage cells (e.g., crush or tear), or indirectly disrupt blood supply to cells and tissues. Extremely low temperatures can damage blood vessels and accelerate some cellular responses, or impair the function of temperature-sensitive enzymes. On the other hand, excessive heat distorts enzymes and other proteins, resulting in cell injury.
Another important cause of cell injury is radiation.
Ionizing and ultraviolet radiation are the worst forms of radiation that cause cellular injury. Radiation, at frequencies above the ultraviolet range, ionizes atoms or molecules, which then directly damage the cell membrane or organ.
In particular, it reacts with DNA to form free radicals. And free radicals are extremely harmful to the body cells which can cause cell death.
In normal cells, sodium-potassium adenosine triphosphates (Na + / K + -ATPases) act as ionic pumps.
In particular, it acts as a carrier of action potential across cell membranes. ATP is required for the survival of each cell. Mitochondria produce this ATP through oxidative phosphorylation. And to carry out this process, three sodium ions will come out from inside the cell and two potassium ions will enter inside. This creates an ion potential. But ischemia disrupts this normal process. This means that the sodium-potassium pump does not work properly. As a result, the amount of calcium, sodium, potassium and H2O inside the cell increases. As a result, the membrane of the endoplasmic reticulum ruptures. And cell death occurs. On the other hand, if the amount of ATP decreases, the cell will either go into a state of anaerobic metabolism or die. Anaerobic metabolism is glycolysis (breakdown of glucose).
This can lead to two types of cell injuries.
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Direct-acting toxins:
Direct-acting toxins are the process of necrosis of a cell by its direct association with molecular material or cellular organelles.
For example, mercury chloride poisoning (as contaminated seafood)
Latent toxin:
In this case, the cell does not come in direct contact with the toxin but converts to the toxin and causes damage to the cell. Protein misfolding can also cause cell necrosis. Normally, the endoplasmic reticulum synthesizes protein, but if a misfolding protein is added to the endoplasmic reticulum, it causes cell necrosis.
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