Frumudauði

Frumudauði is the biological process by which a cell dies and is removed from a living organism. It covers both programmed, regulated forms of cell death and accidental, uncontrolled forms resulting from injury. The concept is central to development, tissue homeostasis, and immune function, as well as to the pathology of many diseases.

The most well characterized form is apoptosis, a controlled process driven by proteases called caspases. Apoptosis can be initiated via intrinsic pathways, often involving mitochondrial signals, or extrinsic pathways initiated by death receptors on the cell surface. Hallmarks include cell shrinkage, chromatin condensation, DNA fragmentation, and membrane changes that promote non-inflammatory clearance by phagocytes.

Necrosis is typically the result of severe injury and is characterized by cell swelling, loss of membrane integrity, and inflammation. Autophagic cell death involves self-digestion through autophagy-related pathways and can act as a survival mechanism that becomes a death pathway under certain conditions.

Beyond these, several regulated forms of cell death have been described, including pyroptosis (inflammatory death mediated by gasdermins and inflammasomes), necroptosis (a regulated necrosis involving RIPK1, RIPK3 and MLKL), and ferroptosis (iron-dependent lipid peroxidation). Anoikis refers to cell death caused by loss of attachment to the surrounding matrix.

Detection methods include TUNEL staining for DNA fragmentation, Annexin V binding assays for early apoptotic cells, and measurement of caspase activity. Understanding frumudauði is important for insights into development, cancer, neurodegenerative diseases, and responses to tissue injury.