Irreversible Cell Injury & Cell Death Flashcards
Severe and persistent cell injury, severe cell membrane dysfunction and mitochondrial damage, increased intracellular Ca levels, “the point of no return”
Irreversible cell injury
Cell death can be divided into two categories, they are…
Necrosis and apoptosis
Physiologic cell death or programmed cell death
Apoptosis
Pathologic cell death
Necrosis
Necrosis characterized by cell swelling to the point of membrane rupture
Oncotic necrosis
Name the category of oncotic necrosis morphology:
Visible swelling, ruptured plasma membrane and organelles, ruptured nucleus, mitochondria swollen with amorphous densities
Ultrastructural
Name the category of oncotic necrosis morphology:
Hypereosinophilic cytoplasm (denatured proteins + loss of ribosomes), nuclear changes (pyknosis, karyorrhexis, and karyolysis)
Microscopic
Nuclear condensation with shrinkage and intense basophilia
Pyknosis
Nuclear fragmentation
Karyorrhexis
Nuclear dissolution or loss
Karyolysis
Name the category of oncotic necrosis morphology:
Swelling and pallor (soon after cell death), loss of structural detail, demarcation from adjacent viable tissue, discolored, soft, appearance highly variable depending on many factors
Macroscopic/Gross
What are the 4 main classifications of necrosis?
Coagulation, caseous, liquefactive/lytic, gangrenous
Type of necrosis typically caused by hypoxia, ischemia, or toxic injury; general tissue structure preserved, cell outlines recognizable, nuclei loss, pale tan/gray or red, solid, and often sharply demarcated from adjacent viable tissue
Coagulation necrosis
A focal area of coagulation necrosis resulting from failure of blood supply (ischemia)
Infarct
When blood enters infarcted tissue because blood flow is restored in the obstructed vessel, or arrived from collateral circulation, it creates a…
Hemorrhagic infarct
When macrophages remove the blood from an acute hemorrhagic infarct, it creates an…
Ischemic (pale) infarct
Obstruction of the venous system by thrombus or external compression creates a…
Venous infarct
(Examples: infarcts created by intestinal volvulus or strangulation lipomas)
Type of necrosis with curdled-cheese gross appearance; older lesion, compete loss of cellular/tissue architecture, cell outlines not visible; crumbled, granular consistency with yellow-white color; mineralization common
Caseous necrosis
Example: Mycobacterium spp (tuberculosis)
Type of necrosis where tissue is in a fluid phase; cells lysed by lytic enzymes of neutrophils; yellow, soft, liquid consistency; loss of tissue/cellular structure, cell outlines not visible; the only kind of necrosis found in the CNS
Liquefactive necrosis
Examples: necrosis of CNS (lack of fibrous tissue to uphold tissue structure) and infection of pyogenic bacteria (at the center of abscesses)
The lessening of density of tissue; loss of neuropil in terms of liquefactive necrosis
Rarefaction
A form of infarction due to loss of blood supply found at the distal aspect of extremities; dry leathery texture, free of bacteria
Dry gangrene
Necrotic tissue invaded by bacteria that occurs commonly in the lungs (aspiration pneumonia) and mammary glands
Wet gangrene
Necrotic tissue invaded by gas forming bacteria
Gas gangrene
Necrosis that occurs secondary to leakage of pancreatic enzymes (lipases) in pancreatitis cases
Enzymatic fat necrosis
Necrosis caused by blunt trauma or chronic pressure against bony prominences (subcutaneous adipose tissue in recumbent animals)
Traumatic fat necrosis
Necrosis of abdominal fat in overconditioned cattle
Idiopathic fat necrosis
Superficial sloughing or exfoliation of dead cells without rupture of basement membrane
Erosion
Full-thickness necrosis of the epithelium with rupture of basement membrane
Ulcer
Consequences of oncotic necrosis include… (multiple answers)
- Elicits an inflammatory reaction
- Formation of a sequestrum
- Inflammation with regeneration
- Inflammation with scar formation
What happens to tissue during inflammation brought on by oncotic necrosis?
Red line encircle necrotic tissue and vessels bring leukocytes to the site to phagocytize the necrotic tissue
What is a sequestrum?
A piece of dead bone tissue occurring within a diseased bone that became separated from normal bone during necrosis
Example: sequelas form during osteomyelitis
When can inflammation with regeneration be utilized effectively by the body
When the defect is shallow and able to be repaired
What occurs during inflammation with scar formation?
Dead tissue is replaced by fibrous connective tissue
What is the purpose of pathologic apoptosis?
Eliminates unwanted, potentially harmful, useless, and damaged cells
Morphologically, how can apoptosis be easily distinguished from necrosis?
Apoptosis involves condensation and shrinkage of the cell, while necrosis typically involves swelling and leakage/rupture of the cell
What are some physiological purposes of apoptosis?
- Programmed cell destruction during embryogenesis
- Shrinkage of organs/tissues deprived of hormonal stim.
- Cell deletion in proliferating cell populations (to maintain homeostasis)
What are some pathologic triggers of apoptosis?
- Injury from toxins/ROS
- Mitochondria and DNA damage (anti-cancer drugs)
- mediated by cytotoxic T cells and NK cells
- Nutrient deprivation
What are some histological characteristics seen in apoptosis?
Cellular shrinkage, intact plasma membrane, no inflammation, individual cells
