#1 cell injury Flashcards
Hyperplasia
Increase in the number of cells (pathogenesis: growth factors may activate signaling pathways that stimulate cell proliferation and/or cells regenerate from stem cells)
Hypertrophy
Increase in the size of a cell (pathogenesis: increased synthesis and assembly of additional intracellular structural components)
Atrophy
Decrease in the size of a cell because of loss of cellular substance (pathogenesis: decreased protein synthesis because of reduced metabolic activity and increased protein degradation in cells)
Metaplasia
Substitution of one type of an adult cell for another type of adult cell (pathogenesis: result of a reprogramming of precursor cells to differentiate along another pathway)
HYPOXIC INJURY MODEL: CELLULAR SWELLING
Cellular swelling is a structural change in the cell caused by an abnormal increase in the water content. NO Oxygen -> no ATP -> no Na+/K+ pump -> increased Na2+ and therefore increased H2O. Also get increased Ca2+ which changes membrane permeability and leaks enzymes
FREE RADICAL INJURY MODEL
A free radical is an atom or group of atoms, which have a single unpaired electron in the outer orbit. Free radicals are chemically unstable and very reactive with components of the cell, such as the membrane and intracytoplasmic organelles. The chemical reaction between the free radical and the cell component may cause irreversible damage and death. The degree of injury is determined by the balance between free radicals and defensive mechanisms, such as intracellular enzymes and antioxidants (vitamin C, vitamin E.).
Necrosis
cell death, with changes to the nucleus and cytoplasm and characterized by the presence of leukocytes (esp. neutrophils) in the dead tissue
why do necrotic cells have increased eosinophilia?
- loss of cytoplasmic RNA (less hematoxylin - the blue dye- staining) 2. in part to denatured cytoplasmic proteins (which bind eosin - the red dye).
Karyolysis
basophilia of the chromatin may fade, a change that reflects loss of DNA because of enzymatic degradation by endonucleases.
Pyknosis
Characterized by nuclear shrinkage and increased basophilia. The chromatin condenses into a solid, shrunken basophilic mass (also seen in apoptosis)
Karyorrhexis
the pyknotic nucleus undergoes fragmentation. In a day or two, the nucleus in the necrotic cell totally disappears.
Hematoxylin and eosin (H&E) staining
used frequently in histology to examine thin sections of tissue. Hematoxylin stains cell nuclei blue; stains RNA-rich portions of cytoplasm blue, stains matrix of hyaline cartilage blue. Eosin stains cytoplasm, connective tissue and other extracellular substances pink or red.
Coagulation Necrosis
severe ischemia, often solid organs (heart and kidney). Appears as ghost-like remnants of intact cells which lack nuclei. The cell outline is preserved; the cytoplasm stains intense pink (eosinophilia). Example: Myocardial infarct/renal infarct.
Liquefactive Necrosis
often associated with bacterial infections. Bacteria release enzymes causing rapid loss of cellular structure and a collection of liquid and amorphous debris. Example: ABSCESSES, a collection of pus (neutrophils, dead cells, liquid). This is also the pattern of necrosis associated with an ischemic brain infarct.
Caseous Necrosis
associated with a unique inflammatory reaction, the granuloma. Caseous necrosis is characterized histologically by amorphous, granular debris (dead cells) in the center of granulomatous cell reaction. (no cellular structure/outlines can be identified). Macroscopically, the necrotic tissue is soft, white and friable. Observed with the unaided eye, caseous necrosis resembles cheese curds. Example: Tuberculous lymph node.
Enzymatic Fat Necrosis
The term is commonly used to describe focal cell death in the pancreas and adjacent fat. Enzymes (lipase) release from damaged pancreatic cells digest or liquefy adipose cells. With lipid breakdown, fatty acids are released and combine with calcium to form yellowish-white insoluble soaps. Example: Acute pancreatitis.
Gangrene
This is a clinical term and represents coagulation (ischemic) necrosis, usually of an extremity and also of bowel and gallbladder. If bacteria contaminate dying tissue, superimposing liquefactive necrosis, the process is referred to as “wet gangrene”.
Apoptosis
A pattern of cell death characterized by nuclear condensation and fragmentation coupled with fragmentation of cytoplasm into “apoptotic bodies.” The apoptotic bodies, containing nuclear fragments, are removed by phagocytosis. Apoptosis is not associated with an inflammatory reaction.
