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Pathology Ch. 2

Cellular reaction to injury

QuestionAnswer
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