What are the characteristics of irreversible cell injury?

There are two main consequences that characterize irreversible cell injury. The first consequence is the inability to reverse mitochondrial dysfunction even once oxygen has been restored. The second main consequence is the occurrence of extreme disturbances in overall membrane function. There is a massive calcium influx into the cell, which activates calcium-dependent catabolic enzymes. Additionally, vital coenzymes, ribonucleic acids, and proteins flow out through the permeable membranes and as a consequence cells lose their ability to generate ATP. An injury to the lysosomal membranes causes leakage of their enzymes into the cytoplasm; the catabolic enzymes become activated in the reduced pH of the ischemic cell and will further damage nuclear and cytoplasmic components. This enzyme leakage and imbalance in pH may lead to increased acidosis in the cellular environment due to the excess acid in the blood as a consequence. Necrosis is a type of irreversible cell injury characterized by cytoplasmic swelling, damage to the plasma membrane and organelle destruction. All of which cause cell death. There are six types of necrosis, coagulative necrosis, liquefactive necrosis, fibroid necrosis, gangrenous necrosis, fat necrosis, and caseous necrosis. Apoptosis is another type of irreversible cell injury. It is a process regulated by caspases which cause cell death through the cleavage of specific proteins in the nucleus and cytoplasm; the dying cells shrink and turn into apoptotic bodies.