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Pathology Ch. 2
Cellular reaction to injury
| Question | Answer |
|---|---|
| When the cell is exposed to excessive physiologic or pathologic stimuli, it may undergo what two changes? | Adaptation; Cell injury- either reversible (degeneration) or irreversible (death, or necrosis) |
| What are 7 major causes of cellular injury? | Hypoxia, Physical agents, Chemical agents, Infectious agents, Genetic defects, Nutritional, Immunologic reactions |
| What is the most common cause of cellular injury? | Hypoxia |
| What is Hypoxia? | Ischemia due to decreased blood supply; Inadequate oxygenation of blood; Loss of oxygen carrying capacity of blood |
| What are physical agents that may cause Cell injury? | Trauma; Thermal Injury (extreme heat or cold); Radiation; Electric injury |
| What are Chemical Agents that may cause cell injury? | Therapeutic agents (aspirin); Non-therapeutic agents (alcohol or lead poisoning) |
| What are infectious agents that may cause cell injury? | Viruses; Bacteria; Fungi; Parasites |
| What is an example of a genetic defect that may cause cell injury? | Congenital malformation |
| What are nutritional imbalances that may cell injury? | Deficiency (avitamoninosis, protein calorie malnutrition); Excess (obesity) |
| What are Immunologic reactions that may cause cell injury? | Hypersensitivity; autoimmune diseases |
| Whether cell damage is reversible or irreversible is dependent on what four factors? | 1. Nature of the agent and it's severity; 2. Duration of the insult; 3. Type of Cell (brain cells- 3-5 mins; myocardial fibers-0.5-2 hrs); 4. Ability of tissue to regenerate |
| What 4 intracellular systems are more vulnerable to cell injury? | 1. Cell membranes; 2. Aerobic respiration and ATP generation; 3. Genetic apparatus; 4. Protein and enzyme synthesis |
| An example of reversible changes are...? | When hypoxia interferes with aerobic respiration in mitochondria |
| Intracellular accumulation of Na+, diffusion of K+ and osmotic gain of water results in what? | 1. Cloudy appearance of swollen cells due to dispersion of cytoplasmic organelles; 2. Cell membrane shows blunting of microvilli |
| Changes in cytoplasmic organelles cause what? | 1. swelling of endoplasmic reticulum; 2. Swelling of mitochondria 3. Swelling of lysosomes |
| What happens with the swelling of endoplasmic reticulum? | Hydropic degeneration; ER appears fragmented, accumulation of detached ribosomes is known as myelin figures |
| What is a fatty change? | Accumulation of fat within parenchymal cells of liver (due to hypoxia, alcohol, or DM); Membrane-bound lysosomes coalesce together producing fatty cysts; Appears as vacuoles due to accumulation of fatty droplets |
| What happens when there is irreversible damage of cell membranes? | Damage of plasma membrane (loss of protein essential enzymes, co-enzymes and RNA); Vacuolization of mitochondria; Release of lysosomal enzymes (digestion of cytoplasm) |
| What is a pyknosis? | small dense nucleus |
| What is karyorrhexis? | fragmentation |
| What is Karyolysis? | dissolution of nucleus by lysosomal enzymes |
| What is the definition of necrosis? | Death of group of cells within a living body caused by injurious agent |
| What are 3 post-necrotic changes? | 1. Nuclear changes- Pyknosis, Karyorrhexis, Karyolysis 2. Cytoplasmic change- Swollen 3. Architectural changes- depend on whether denaturation of proteins or enzymatic digestion prevails |
| What are the two ways necrotic cells injure cells? | Denaturation of proteins and Enzymatic digestion |
| What is denaturation of proteins? | Necrotic cells preserve the outline of original tissue |
| What is enzymatic digestion? | Cell lysis (autolysis, or heterolysis), necrotic tissue appears without structure (liquifactive necrosis) |
| What are 7 types of necrosis? | Coagulative necrosis, Colliquative (liquefactive) necrosis, Caseous necrosis, Enzymatic fat necrosis, Traumatic fat necrosis, Fibrinoid necrosis, Gangrene |
| What is the most common type of Necrosis? | Coagulative Necrosis |
| What is the cause of coagulative necrosis? | ischemia |
| How does coagulative necrosis appear to the N.E.? | area appears pale, firm, and swollen |
| How does coagulative necrosis appear under a microscope? | Cells devoid of nuclei appear as mass of pink homogenous cytoplasm; keep outline for several days till removed by phagocytosis |
| What is the mechanism of colliquative (liquifactive) necrosis? | Cell lysis prevails over protein denaturation; necrotic tissue: soft, liquid-like |
| What are some causes of colliquative (liquefactive) necrosis? | necrotic lesions of brain: more abundant lysomal enzymes and lack of good structural support; Suppurative inflammation (abscess): potent proteolytic enzymes of neutrophils |
| In what kind of necrosis does the necrotic tissue appear white and cheesy? | Caseous necrosis |
| What is the cause of Caseous necrosis? | TB |
| What are three mechanisms of Caseous necrosis? | 1. Coagulative necrosis w/ partial liquefaction 2. Necrotic cells neither retain their outline nor disappear by lysis 3. appear as amorphous debris of fragmented coagulated cells. |
| What is the cause of enzymatic fat necrosis? | Release of pancreatic enzymes into surrounding tissue (ex: traumatic injury, acute pancreatitis) |
| What is an important mechanism in enzymatic fat necrosis? | Fatty acids combine w/ calcium --> calcium soaps: hard chalky white patches, formed of necrotic fat cells, calcification and fibrosis |
| What is the cause of traumatic fat necrosis? | Trauma (not enzymatic digestion) to fatty tissue e.g. breast, subcutaneous tissue |
| What is the mechanism for traumatic fat necrosis? | Release of intracellular fat--> acute inflammation and fibrosis--> firm mass mistaken for breast cancer |
| What is fibrinoid necrosis? | loss of normal structure, it's replacement by eosinphilic material that resembled fibrin |
| What are two causes of fibrinoid necrosis? | 1. malignant HTN--> necrosis of tunica media of arterioles, leakage of plasma protein and deposition of fibrin. 2. Autoimmune diseases: synovial membranes in rheumatoid arthritis (immune complexes, breakdown products of collagen and fibrin) |
| What is gangrene? | mass necrosis of tissue due to vascular occlusion followed by putrefaction |
| What are three types of gangrene? | Dry, wet and gas |
| Where does dry gangrene occur? | in the toes and feet due to gradual occlusion of arteries (e.g. atherosclerosis and diabetes) --> coagulative necrosis |
| What marks the area between gangrenous area and living tissue? | Line of demarcation |
| Where does wet gangrene occur? | Limbs (crush injury) and internal organs (intestinal strangulation) --> occlusion of both artery and vein |
| In which gangrene is the necrotic tissue more prone to severe bacteria infection, liquefaction and toxemia? | wet gangrene |
| Which type of gangrene has both tissue necrosis and putrefaction which are caused by bacteria? | gas gangrene |
| Which type of gangrene is due to contamination of deep wounds involving muscles with clostridium perfringens? | gas gangrene |
| Which type of gangrene has crackling sensation of palpation? | gas gangrene |
| What is apoptosis? | death of single cells within clusters of other cells |
| What are apoptotic bodies also known as? | councilman bodies |
Created by:
courtney.marie23
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