Week 1: Cell Injury & Death Flashcards
cellular changes that occur with apoptosis (3)
Defined fragmentation of DNA
Formation of distinct structures called apoptotic bodies
No inflammatory response, cells removed by phagocytosis
define apoptosis
cell death due to physiological turnover, programmed cell death; can be stimulated by physiologic or pathologic stimuli
changes in nucleus during necrosis (3 - define each)
karyolysis: DNA is degraded by lysing of the nucleus
pykinosis: nucleus shrinks in size
karyorrhexis: nucleus becomes fragmented
define necrosis
cell death by injury, involves autodigestion and may initiate an inflammatory response
define gas gangrene
occurs when infection is caused by clostridium spp., anaerobic bacteria that produce toxins that damage CT and cause gas
define wet gangrene
occurs when necrotic tissue is infected with bacteria and phagocytic cells are recruited – releasing enzymes that lead to liquefactive process
define dry gangrene
coagulative necrosis
cellular changes due to fat necrosis
saponification = formation of soap by fatty acids, triglycerides, calcium, magnesium and sodium
where does fat necrosis occur?
pancreas, breast, peritoneal cavity
define fat necrosis
occurs due to abnormal release of pancreatic enzymes that enter other structures. lipases cause specific cellular dissolution
cell changes that occur with caseous necrosis
- Necrotic debris not digested completely by hydrolases
2. Tissues appear soft and granular (white and cheesy)
causes of caseous necrosis
limited # of agents
common cause = TB
define caseous necrosis
combination of coagulative and liquefactive necrosis
cell changes with liquefactive necrosis (2)
- Digestion of the cell remains
- Associated with abscess (pus) formation
examples of liquefactive necrosis
- Characteristic of hypoxic death in CNS cells – rich in hydrolytic enzymes and lipids
- Characteristic of focal bacterial infections, which involve hydrolases from phagocytic neutrophils
liquefactive necrosis is the consequence of: _____ or _____
autolysis (destruction from within the cell) or heterolysis (destruction from outside of the cell)
cell changes that occur in coagulative necrosis (3)
- cell outline preserved
- acidosis denatures proteins
- protein denaturation causes coagulation
what is coagulative necrosis and in which organs does it occur?
cell death due to hypoxia and/or ischemia
found in the heart, kidneys and adrenal gland
characteristic of hypoxic death in all cells except brain cells
How does calcium influx affect mitochondria and the nucleus, leading to cell death?
mitochondria: disrupts normal cellular metabolism
nucleus: gene transcription and nucleases are modulated by the calcium which leads to apoptosis
how do ROS contribute to cell injury/death?
ROS work similarly as free radicals - damage cell membranes
how do ROS form under stress?
increase in ROS levels occurs under oxidative stress
how does a cell normally protect against ROS?
- superoxide dismutase converts superoxide to hydrogen peroxide
- catalase converts hydrogen peroxide to oxygen and water