Cell Adaptation and Death

Cell Adaptation & Death Examples of epithelial, connective & other cell types: Epithelial: Squamous, cuboidal, columnar (e.g., skin, intestines). Connective: Fibroblasts, adipocytes, chondrocytes (e.g., bone, cartilage, fat). Other: Muscle cells (skeletal, cardiac, smooth), neurons. L...

Cell Adaptation & Death Examples of epithelial, connective & other cell types: Epithelial: Squamous, cuboidal, columnar (e.g., skin, intestines). Connective: Fibroblasts, adipocytes, chondrocytes (e.g., bone, cartilage, fat). Other: Muscle cells (skeletal, cardiac, smooth), neurons. Labile, stable & permanent cells: Labile: Constantly dividing (e.g., skin, gut epithelium). Stable: Divide when needed (e.g., liver, kidney). Permanent: Cannot divide (e.g., neurons, cardiac muscle). Apoptosis vs. necrosis: Apoptosis: Programmed cell death, no inflammation. Necrosis: Uncontrolled cell death, causes inflammation. Infarct definition & occurrence: Tissue death due to lack of blood supply (e.g., myocardial infarction). Factors determining atrophy or infarction: Blood supply, oxygen availability, workload, hormonal signals. Ageing effects on cells & organs: Reduced cell division, DNA damage, accumulation of waste products, organ shrinkage. Types of cellular adaptation & reversibility: Hypertrophy (↑ size), Hyperplasia (↑ number), Atrophy (↓ size), Metaplasia (change in cell type). Most are reversible except metaplasia if it progresses to dysplasia. Metaplasia definition: Change in one cell type to another (e.g., smoking causes columnar cells in the bronchi to become squamous). Type of cell death in normal embryogenesis & inflammatory response: Apoptosis occurs without inflammation. Cellular processes leading to tissue/organ size increase: Hypertrophy (cell enlargement) & Hyperplasia (cell multiplication). Cellular processes leading to tissue/organ size decrease: Atrophy (cell shrinkage) & Apoptosis (programmed cell death). Example of a permanent cell type: Neurons or cardiac muscle cells. Epithelium best for withstanding physical stress: Stratified squamous epithelium (e.g., skin, esophagus)..