Cell Injury and Cell Death I and II Flashcards
Why is an elevated blood level of cardiac troponin used as an indicator of a myocardial infarct?
- cardiac troponin is normally found inside cardiac muscle cells
- when the cells infarct, they lyse and release the protein in the blood stream
- since this protein is not normally found in the blood, and is not found in any other tissue, it can be measured to determine if a myocardial infarct is occurring or has recently occurred
*at least two hours after injury
0.07 spike for minor myocardial infarction
50 spike for acute MI
myocarditis: trop level stays around 0.05 limit
What are the three types of irreversible nuclear changes?
- pyknosis
- karyorrhexis
- karyholysis
What happens to the nucleus in pyknosis?
nucleus compacts
What happens to the nucleus in karyorrhexis?
chromatin breaks into smaller pieces
What happens to the nucleus in karyolysis?
chromatin begins to dissolve
What are possible causes of hypoxia without ischemia?
- high altitude
- sickle cell anemia
(shows as bright red blood in CO poisoning)
What are the six types of necrosis?
- coagulation necrosis
- liquefactive necrosis
- fat necrosis
- caseous necrosis
- fibroid necrosis
- gangrenous necrosis
What are the etiology and morphologic features of coagulation necrosis?
Cause: hypoxic cell of death
Grossly: appear white (lighter than the normal tissue) and wedge-shaped from the point at which the ischemia occurred
Microscopically:
- cells maintain structure but lack nuclei (or have nuclear changes indicative of cell death)
- very eosinophilic (red=death)
- protein denaturation is the dominant feature (red!)
- neutrophils present to clean
What are the etiology and morphologic features of liquefactive necrosis?
Cause: focal infection by bacteria or fungi due to accumulation of inflammatory cells (neutrophils)
Grossly:
appears as abscess (pus collection)
Microscopically:
- appears as though cells are digested
- neutrophils and debris are present
- tissue digestion is the dominant feature
What are the etiology and morphologic features of fat necrosis?
Cause: acute pancreatitis or trauma leads to digestion of fat cell membranes and the triglycerides stored in fat cells
(issue with diseased neighboring tissue –> cells die, release contents which attack adjacent adipose tissue)
Grossly:
tissue looks chalky due to saponification (combination of fat tissue with calcium)
Microscopically:
- vague outlines of fat cells are present
What are the etiology and morphologic features of caseous necrosis?
Cause: chronic inflammation, certain infections (ex: TB, valley fever-coccidioides immitis) that the body can’t fight are walled off in the body, forming granulomas
Microscopically:
- granulomas - center part becomes filled with dead cells and debris
- cells do not retain their outlines and appear as granular eosinophilic cell debris
What are the etiology and morphologic features of fibrinoid necrosis?
Cause/Location: injured blood vessels
Microscopically:
- tissue appears bright pink and granular, resembling fibrin
- composed of fibrin, plasma proteins, and complement
(fibrin: acute inflammation for forming clots)
What are the etiology and morphologic features of gangrenous necrosis?
Ischemic necrosis
Cause: low blood flow; usually portion of lower extremities (similar to coagulative, but due to location, called gangrenous)
If bacterial and inflammatory cells are less involved: resembles coagulative necrosis
(dry gangrene; ex: frost bite)
If bacterial and inflammatory cells are recruited: resembles liquefactive necrosis
(wet gangrene; ex: diabetes)
Summarize the molecular changes occurring in cells exposed to hypoxia and relate these changes to the microscopic appearance of reversibly, and irreversibly, injured cells.
- lack of oxygen prevents mitochondria from generating ATP via oxidative phosphorylation
- as ATP production falls, sodium and potassium pumps shut down. Sodium and calcium enter the cell; potassium leaves. Water also enters the cell, causing swelling
- ATP is now produced by glycolysis; lactic acid accumulates in the cell. The lower cell pH causes changes in chromatin (clumps) and proteins
- ribosomes detach from the RER; protein synthesis is compromised; lipids accumulate in cell –> lipoproteins not formed b/c protein synthesis decreased
- the extra water in the cell that causes swelling also effects the ER and mitochondria. This change is reversible if oxygen is returned to the cell
- if oxygen does not return, the chromatin will condense into a very dense state before breaking up into chunks and then nucleic acids
- the presence of calcium in the cells over physiologic levels activates enzymes that will break down cellular components
- the membranes will lyse, including that of the mitochondria, ER, and Golgi
Due to ATP production by glycolysis and lactic acid accumulation in the cell, pH is lowered (cell more acidic). What happens to the nucleus?
- chromatin clumps
if oxygen does not return to cell, chromatin will condense into a very dense state before breaking up into chunks and then nucleic acids
