Cell Injury, Adaptations and Death Flashcards
Examples of labile tissues.
Hematopoietic cells, surface epithelia (linings of upper airways, gastrointestinal tract, skin etc.)
Examples of stable tissues.
Parenchyma of most solid organs (liver, kidney, pancreas).
Endothelial cells, fibroblasts, smooth muscle cells.
Examples of permanent tissues.
Neurons
Cardiac myocytes
-Heal with connective tissue
What is cellular hypertrophy?
Increase in size of cells = increase in size of organ
Examples of physiologic hypertrophy.
Skeletal muscle hypertrophy in weight lifting
Uterus in pregnancy
Examples of pathologic hypertrophy.
Cardiac muscle hypertrophy with hypertension
What is hyperplasia?
Increase in cell number. Occurs in cells capable of division (labile and stable cells)
Examples of physiologic hyperplasia.
Hormonal hyperplasia of female breast at puberty and in pregnancy.
Compensatory hyperplasia of liver after partial resection.
Connective tissue response with wound healing.
Examples of pathologic hyperplasia.
Hormonal imbalance stimulating endometrial hyperplasia with menopause.
Benign prostatic hyperplasia (BPH) – formation of nodules in prostate gland.
Skin warts and mucosal lesions associated with viral infections (papilloma virus).
Is enlargement of the uterus during pregnancy hypertrophy or hyperplasia?
Both!!
What is atrophy?
Decrease in size of a cell due to loss of cell substance. If severe – decreased organ size.
Physiologic cause: loss of hormonal stimulation (endometrium at menopause)
Pathologic cause: decreased functional demand (arm in cast), loss of innervation, inadequate nutrition
What is metaplasia?
When one adult cell type is replaced by another adult cell type that is better able to handle a stress.
Explain some examples of epithelial metaplasia.
Ciliated columnar epithelium becomes squamous epithelium (trachea/bronchi of smokers)
Squamous epithelium become gastric/intestinal (glandular) type epithelium (distal esophagus in those with reflux)
Columnar becomes squamous in endocervix with increased risk of HPV infection
Explain an example of mesenchymal metaplasia.
Bone formation in soft tissue (muscle/connective tissue) at sites of injury.
What constitutes irreversible cell injury?
Inability to reverse mitochondrial dysfunction, disturbance of membrane function
Two types: necrosis, apoptosis
Explain necrosis.
Cell size enlarges (swells).
Nucleus – pyknosis, karyorrhexis, karyolysis.
Plasma membrane disrupted.
Cellular contents undergo enzymatic digestion, may leak out of cell.
Adjacent inflammation frequent.
Invariably pathologic.
Explain apoptosis.
Cell cell is reduced.
Nucleus – fragments into nucleosome-size fragments
Plasma membrane intact but altered structure.
Cellular contents intact, may be released in apoptotic bodies.
No adjacent inflammation.
Often physiologic eliminating unwanted cells.
What constitutes reversible cell injury?
Fatty change – lipid vacuoles in cytoplasm, from toxic or hypoxic injury, primarily in cells dependent on fat metabolism (i.e. fatty liver secondary to toxins)
Cellular swelling – hydropic change or vacuolar degeneration, from failure of membrane pumps to maintain homeostasis (membrane blebs), vacuoles appear in cells corresponding to distended endoplasmic reticulum.
What does a fatty liver look like and why?
Yellow color and “greasiness” indicates steatosis.
Hepatocytes are injured resulting in an intracellular accumulation of triglycerides, liver enlargement and elevated liver enzymes.
Clinical manifestations depend upon specific cause and how severe.
Why does accumulation occur in a fatty liver?
Impairment of microsomal and mitochondrial functions.
Decreased fatty acid oxidation.
Decreased apoprotein formation.
Increased mobilization of fatty acids from periphery.
What are some morphologic features of necrosis?
Increased eosinophilia, nuclear shrinkage, fragmentation, breakdown of plasma membrane and organelle membranes.
Results from hypoxic or anoxic injury due to ischemia.
Persistence of dead cells with intact outlines but with loss of cellular details – denatures cellular proteins and enzymes.
Occurs in all solid organs.
Coagulative Necrosis
Complete digest of dead cells.
Common with bacterial or fungal infections – stimulate accumulation of WBC, necrotic cells together with acute inflammatory cells = pus.
Liquefactive Necrosis
What kind of necrosis are brain infarcts?
Liquefactive Necrosis
