Cellular Responses to Stress and Toxic Insults: Adaptations, Injury, and Death Flashcards
Hypertrophy
Increase in size of cell via growth factors
Physiologic Hypertrophy
Seen during increased demand such as exercise (skeletal muscle hypertrophy)
Pathologic Hypertrophy
Hypertrophic heart due to hypertension
Via gene protein synthesis and production of orgenelles
Selective hypertrophy
Increase in size of subcellular organelle
Example: barbiturates (hypertrophy of the SER)
Alcohol intake (hypertropgy of the SER)
Hyperplasia
Increase in the number of cells that also cause increase in organ mass from stem cells
Physiologic Hyperplasia
Hormone induced: growth of breasts in puberty, gravid uterus
Compensatory Hyperplasia: regeneration of liver after partial hepatectomy
Pathologic Hyperplasia
Occurs due to underlying pathologic process, incred risk for cancer; driven by growth factors/hormones
Endometrial Hyperplasia from PCOD –> Malignant transformation (endometrial carcinoma)
Prostatic Hyperplasia –> BPH, no malignancy
Viral infections: HSV, no malignancy
Atrophy
Apoptosis (Decrease in cell number)
Autophagy - ubiquitin decrease in cell size
Physiologic Atrophy
Notochord and thyroglossal duct undergo atrophy during feta development,
If duct persists –> thyroglossal dust
Pathologic Atrophy
1 - Decreased work load (disuse atrophy)
2 - Loss of innervation (nerve damage)
3 - Diminished blood supply (may eventually lead to apoptosis of cells/organs –> renal and spleen arteries
4 - Sickle cell repeated vasculoocclusive cyst
5 - Inadequate nutrition
6 - Loss of endo stimulation
7 - Pressure induced atrophy (tumor)
Via ubiquitin-proteasome pathway: cytoskeleton breaksdown; overactivity –> cancer cachexia
Atrophic cells residual bodies
Residual bodies are the parts not digested during autophagic lysosomal digestion
Atrophic residual bodies example: Brown atrophy of the heart/liver in elderly from lipofuscin granules
From lipofuscin granules found in cytoplasm
Metaplasia
Reversible change in which one differentiated cell type is replaced by another type of cell.
Occurs in epithelial and connective tissues
Metaplasia Epithelial Examples (2)
At risk for malignancy
- Smoker: ciliated columnar is replaced by squamous epithelium (at risk for squamous cell carcinoma)
- Barret esopohagus: lower esophagus squamous epithelium is replaced by intestinal epithelium with goblet cells (intestinal metaplasia) –> at rish for adenocarcinoma of the esophagus
Connective Tissue Metaplasia (no malignancy)
Myositis Ossificans: formation of bone in connective tissue
No malignancy
Other sites of metaplasia
Vit. A deficiency/keratomalacia: sqaumous metaplasia of the respiratory tract and urinary tract, thickness of conjunctivia
Metaplasia mechanism:
Reprogramming of stem cells and it’s signaling.
E.g. Tx of GERD: decrease in acid
Causes of cell injury (7)
- oxygen deprivation
- Physical agents
- Chemical agents and drugs
- Infectious agents
- Immunologic rxns
- Genetic derangments
- Nutritional imbalances
Necrosis:
Leaks contents
Associated with inflammaation
Pyknosis–> karyorrhexis –> karyolysisi
Pathologic
Apoptosis
No leakage of contents No inflammation Reduced shrinkage Nucleosome fragmentation Pathologic Physiologic (often)
Morphologic Changes in Cell Injury
Cellular swelling (ion pumps fail in membrane)
Small clear vacuoles in cytoplasm
Incresed in eosinophilic staining
Ultra structural changes of cell injury: plasma membrane
Blebbing (early ischemia), blunting, loss of microvilli
Ultra structural changes of cell injury : mitochondria
swelling and amorphous densities
Ultra structural changes of cell injury : ER
Dilatation, detachment of polysomes, intracytoplasmic myelin figures
Ultra structural changes of cell injury: Nucleus
disaggregation of granular and fibrallar elements
Necrosis:
result of denaturation of intracellular proteins and enzymatic digestion of lethally injured cells
Necrosis: morphologic changes
Increased eosinophilia, glassy homogenous experience
Necrosis: nuclear changes
Pyknosis: nuclear shrinking, increased basaphilia,
Karyarrhexis: fragmentation of pyknotic nucleus
Karyolysis: fading of the basophilia of the chromatin
Types of Necrosis (6)
Coagulative, Liquefactive, Gangrenous, Caseous, Fat, Fibrinoid
Coagulative
Preservation of the structural outline of dead cells; nucleus disappears
WEDGE-SHAPED
Spleen, Kidney, and heart
