Describe the biochemical mechanism leading to cell membrane damage.

Mechanisms of cell Membrane Damage:

• Reactive oxygen species. Oxygen free radicals cause injury to cell membranes by lipid peroxidation.
• Decreased phospholipid synthesis. The production of phospholipids in cells may be reduced as a consequence of defective mitochondrial function or hypoxia, both of which decrease the production of ATP and thus affect energy-dependent biosynthetic pathways. The decreased phospholipid synthesis may affect all cellular membranes, including the mitochondria themselves.
• Increased phospholipid breakdown. Severe cell injury is associated with increased degradation of membrane phospholipids, probably due to activation of calciumdependent phospholipases by increased levels of cytosolic and mitochondrial Ca2+.
• Cytoskeletal abnormalities. Cytoskeletal filaments serve as anchors connecting the plasma membrane to the cell interior. Activation of proteases by increased cytosolic calcium may cause damage to elements of the cytoskeleton.

Describe the effects of cellmembrane damage.

Plasma membrane damage results in loss of osmotic balance and influx of fluids and ions as well as loss of proteins, enzymes, co-enzymes and ribonucleic acids. The cells may also leak metabolites, which are vital for the reconstitution of ATP thus further depleting net intracellular high energy phosphates. Injury to lysosomal membranes results in leakage of their enzymes into the cytoplasm and activation of these enzymes. Activation of these enzyme leads to enzymatic digestion of cell components resulting in loss of ribonucleoprotein, deoxyribonucleoprotein and glycogen and the cells die by necrosis.