Cellular Senescence
A state in which a cell has permanently stopped dividing but remains metabolically active. Senescent cells accumulate throughout tissues with age. They secrete a mix of inflammatory signals called the senescence-associated secretory phenotype (SASP), which drives local tissue inflammation, disrupts neighboring cells, and contributes to the chronic low-grade inflammatory state known as inflammaging. Senescence plays protective roles in youth (wound healing, tumor suppression) but becomes harmful when cells accumulate faster than they are cleared.