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Due to these internal and external insults, cells lose their ability to regenerate, which ultimately leads to mechanical and chemical exhaustion. Some insults include chemicals in the air, food, or smoke. Other insults may be things such as viruses, trauma, free radicals, cross-linking, and high body temperature. [15]
Oxidative stress mechanisms in tissue injury. Free radical toxicity induced by xenobiotics and the subsequent detoxification by cellular enzymes (termination).. Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. [1]
Mechanistic evidence was provided by Denham Harman's free radical theory of aging, created in the 1950s. This theory stated that organisms age over time due to the accumulation of damage from free radicals in the body. [4] It also showed that metabolic processes, specifically the mitochondria, are prominent producers of free radicals. [4]
Lipid peroxidation is a self-propagating chain reaction and will proceed until the lipid substrate is consumed and the last two remaining radicals combine, or a reaction which terminates it occurs. [3] Termination can occur when two lipid hydroperoxyl radicals (LOO•) react to form peroxide and oxygen (O 2).
The free radical theory of aging states that organisms age because cells accumulate free radical damage over time. [1] A free radical is any atom or molecule that has a single unpaired electron in an outer shell. [2] While a few free radicals such as melanin are not chemically reactive, most biologically relevant free radicals are highly ...
Free-radical theory: Damage by free radicals, or more generally reactive oxygen species or oxidative stress, create damage that may give rise to the symptoms we recognise as ageing. [99] The effect of calorie restriction may be due to increased formation of free radicals within the mitochondria , causing a secondary induction of increased ...
In living organisms, which are composed mostly of water, majority of the damage is caused by the reactive oxygen species, free radicals produced from water. The free radicals attack the biomolecules forming structures within the cells, causing oxidative stress (a cumulative damage which may be significant enough to cause the cell death, or may ...
A free-radical reaction is any chemical reaction involving free radicals. This reaction type is abundant in organic reactions . Two pioneering studies into free radical reactions have been the discovery of the triphenylmethyl radical by Moses Gomberg (1900) and the lead-mirror experiment [ 1 ] described by Friedrich Paneth in 1927.