Cell injury and death Flashcards
Common causes of reversible cellular injury
Trauma - concussion, frost bite
Hypoxia
Ischemia
Hypoxia
decreased availability of oxygen - pneumonia or CO
loss of oxygen carrying capacity of the blood
Loss RBCs anemia
Brain (neurons) most sensitive
Ischemia
insufficient blood supply
absence of oxygen AND nutrients
occlusion of an artery or vein
common causes of irreversible cell injury
hypoxia - brain cells Ischemia - cardiac cells Physical agents - trauma Chemical agents - drug infectious agents immunologic reactions genetic disease nutritional disorders
Apoptosis
cell has internal signal for death
programmed cell death
clean way to die and remove cell
No inflammation - prevents damage to adjacent cells
Where is apoptosis commonly seen?
embryogenesis hormone induced changes mild trauma or injury removing nonfunctional cells chemo & radiotherapy - Neurons more resistant Immune reactions Atrophy Graft vs host disease some viral diseases
Events of Apoptosis
cell becomes densely eosinophilic shrinks with pyknosis of nucleus cytoplasmic blebs phagocytosis of apoptoic bodies cell fragments
What is the definition of pathology?
The study of disease
What does it mean when a cell experiences hyperplasia?
Increase in the number of cells in any organ tissue
What are the etiological reasons for cells to undergo hyperplasia?
Physiologic - hormone induced
Compensatory - callus formation
Pathologic - viral infection causing warts
What does it mean when a cell undergoes hypertrophy?
Increase size of the cell or organ
What is the parthenogenesis of hypertrophy?
Increased functional demand (running) Hormonal stimulation (thyroxin)
What does it mean when a cell experiences atrophy?
Shrinkage in the size of the cell by loss of structural components
What could cause a cell to enter an atrophic state?
Dec workload Loss of innervation Diminished blood supply Inadequate nutrition Loss of endocrine stimulation
What does it mean when a cell undergoes metaplasia?
Reversible change in which one adult epithelial cell type is replaced by another adult type epithelium
What could happen if there was a pathologic and prolonged irritation causing metaplasia?
Dysplasia which can lead to Cancer (squamous cell)
What does it mean when a cell experiences dysplasia?
Epithelial or mesenchymal cells that have undergone metaplasia then atypical cytogical alterations involving cell size, shape and orientation
What can dysplasia lead to?
Cancer (a neoplasia/uncontrolled growth)
What is the chaperone ubiquitin-protease?
An intracellular accumulant which causes the cells to obtain a yellow tinge with aging
What is antracosis?
Carbon pigment in the lung
inc in smokers
What are some example of intracellular accumulations?
Lipofuscin Melanin Iron Calcium Fat Bilirubin
What is lipofuscin?
A yellow pigment that occurs both physiologically and pathologically that is left over from the breakdown and absorption of damaged blood cells
Likes the heart
What causes an increase in melanin?
Tanning
What does a bruise turn brown?
Due to iron deposition and hemosiderin
What could cause an accumulation of bilirubin?
Bile duct occulsion Alcoholism Drugs Hemolytic anemia Pancreatic tumors
What are the functions to regulate cell populations due to apoptosis?
Calcium sensitive endonuclease leading to pyknosis Transgluaminase activity causing cytoplasmic shrinkage by cross linking proteins Gene activation (bcl-2, c-myc, p53)
What are the four factors that could lead to apoptosis?
Injury from radiation, toxins and free radicals
Withdrawal of growth factors
Receptor ligand interactions
Cytotoxic T cells
What are the steps to apoptosis?
Intrinsic embryogenic e Execute caspases Catabolism of cytoskeleton Apoptotic body with ligand receptors Ingested by macrophage
What is nuclear pyknosis?
Ink-dot appearance that represents the first light microscopic evidence of cell death
What is the normal pathway for apoptosis when viewed in a light microscope?
Pyknosis > karyorrhexis (fragments) > karyolysis (full breakdown)
How is aging death by apoptosis?
Sub lethal cellular injury
Programmed genetically by chromosome 1 induced telmoric shortening
Limited number of cell division due to telomeres
Renegade cells (cancer)
What are the 4 forms of necrosis?
Coagulation, liquid, caseous and fat
What does coagulative tissue look like?
Looks like the tissue was boiled
Outline of cell preserved
Seen in hypoxic death (except brain)
Anucleate eosinophils
What are the best examples of coagulative necrosis?
Kidney and myocardium
What characterizes liquefactive necrosis?
Progressive degradation of cell by enzymes and denaturation of proteins either by autolysis or heterolysis
Seen with fungal/bacterial infections
Where is liquefactive necrosis often seen?
The brain
What is fat necrosis?
Saponification of fat cells with calcification due to enzymatic breakdown of lipases
Dystropic calcification
Where does fat necrosis tend to occur?
Breast and liver
Can be seen along with cancer
How is caseous necrosis characterized?
Distinct pattern of centralized amorphous debris and surrounding granulomas
What is gangrenous necrosis?
Not a distinct pattern and happens to hypoxic limbs
Combo of coagulative (dry) and liquefactive necrosis
What is fibrinoid necrosis?
Accumulation of amorphous, basic, proteinaceous material in the tissue matrix that stains like fibrin
