Oxidative stress

Oxidative stress is a biological imbalance in which reactive molecules damage cellular components faster than antioxidant defenses can control them.

Reactive oxygen species: Oxygen-containing molecules that readily react with cellular molecules, including superoxide, hydrogen peroxide, and hydroxyl radicals. These are major reactive agents that can drive oxidative damage.
Oxidation-reduction reaction: A chemical reaction involving the transfer of electrons between substances. Oxidative stress arises from disrupted control of electron-transfer chemistry in cells.
Ischemia-reperfusion injury: Tissue damage that occurs when blood supply returns after a period of restricted blood flow. Reoxygenation can produce a burst of reactive molecules that worsens tissue injury.
Redox signaling: Cellular communication in which reversible oxidation of specific molecules regulates biological processes. Controlled redox signaling uses reactive molecules without constituting uncontrolled oxidative damage.
Free radical: An atom or molecule containing an unpaired electron, often making it chemically reactive. Many oxidants that damage cells are free radicals, though not all reactive oxygen species are.
Redox potential: A measure of a chemical system’s tendency to accept or donate electrons. It describes the chemical conditions that shape cellular oxidation and reduction.
Atherosclerosis: A disease in which plaques build up inside arteries and restrict blood flow. Oxidative modification of low-density lipoprotein contributes to plaque development.
Antioxidant therapy: The use of antioxidant compounds as interventions intended to prevent or treat disease. Reducing oxidants does not reliably improve health, because oxidants also serve normal functions.
Lipid peroxidation: A chain reaction in which oxidants attack lipids, especially polyunsaturated fatty acids in membranes. It shows how oxidative damage can propagate through cell membranes.
Mitochondrion: A membrane-bound organelle that produces much of a eukaryotic cell’s ATP through respiration. Electron transport in mitochondria can generate reactive oxygen species.

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