Cellular Response to Stress and Toxic insult Flashcards
Define Hypertrophy
increase in the size of cells
In regards to hypertrophy, as the size of cells increases, what is going on inside the cell?
increase in protein synthesis and in the size or number of intracellular organelles
Define hyperplasia
increase in the number of cells
This is the failure of cell production.
aplasia
During fetal development, aplasia results in what?
agenesis, or absence of an organ due to failure of production
This is a decrease in cell production that is less extreme than aplasia
hypoplasia
What syndromes is hypoplasia seen in?
Turner and Klinefelter syndromes - partial lack of growth and maturation of gonadal structures
This is a decrease in the size of an organ or tissue and results from a decrease in the mass of preexisting cells
atrophy
What are the most common causes of atrophy?
disuse, nutritional or oxygen deprivation, diminished endocrine stimulation, aging, and denervation
Define Metaplasia
replacement of one differentiated tissue by another
Ischemia, anemia, carbon monoxide poisoning, decreased perfusion, poor oxygenation are all what types of cell injury?
hypoxic
Describe the sequence of events that occurs in the early stage of hypoxic cell injury
- decreased oxidative phosphorylation and ATP production by mitochondria
- failure of the cell membrane pump (intracellular Na+ increase, intracellular K+ decrease)
- cellular swelling - disaggregation of ribosomes
- stimulation of PFK activity = increased glycolysis, decreased intracellular pH
- clumping of nuclear chromatin
Describe what occurs in the late stage of hypoxic cell injury
membrane damage to plasma and lysosomal and organelle membranes with a loss of membrane phospholipids
What are two morphologic signs of hypoxic cell damage seen in the late stage?
myelin figures, cell blebs
Intracellular enzymes such as glutathione peroxidase, catalase, and superoxide dismutase 2 do what?
degrade free radicals
Which vitamins are capable of degrading free radicals?
A, C, and E
What are some of the pathologic effects of ROS production?
membrane damage, protein misfolding, mutations
In regards to hypoxic cell injury, what does the resultant increase in cytosolic Ca2+ cause?
activation of cellular enzymes like proteases, phospholipases - membrane damage; endonucleases - nuclear damage, and ATPase - decrease in ATP
This is the sum of the degradative and inflammatory reactions occurring after tissue death caused by injury; it occurs within living organisms
necrosis
The following describes what type of necrosis:
ischemia, particular the heart and kidney; general preservation of tissue architecture; increased cytoplasmic eosinophilia
coagulative necrosis
The following describes what type of necrosis:
ischemic injury to the CNS (autolytic); suppurative infections characterized by the formation of pus (heterolytic)
liquefactive necrosis
The following describes what type of necrosis:
occurs as part of granulomatous inflammation; seen with tuberculosis; combination of coagulative and liquefactive necrosis; amorphous eosinophilic appearance
caseous necrosis
The following describes what type of necrosis:
lower extremities or bowel and is secondary to vascular occlusion; wet gangrene; dry gangrene
gangrenous necrosis
The following describes what type of necrosis:
often associated with immune-mediated vascular damage
fibrinoid necrosis
Is fat necrosis possible?
yes
Define apoptosis
programmed cell death
Describe the sequence of apoptosis starting from normal cell to apoptotic bodies
- normal cell
- cell shrinkage, chromatin condensing
- membrane blebbing
- nuclear collapse, continued blebbing
- apoptotic body formation
- lysis of apoptotic bodies
True or false, apoptosis induces an inflammatory response.
false - no inflammatory response
Describe the Extrinsic pathway of apoptosis
- FAS ligand binds FAS
- Activation of caspases
- cascade of caspases leads to terminal caspases-3 and 6
Describe the Intrinsic pathway of apoptosis
- lack of survival signals (growth factor)
- loss of bcd-2 (anti-apoptotic protein) from inner mitochondrial membrane
- increased mitochondrial permeability - release of cyt c
- stimulation of proapoptotic proteins bax and bak
- cyt c interacts with Apaf-1 causing self-cleavage and activation of caspase-9 - apoptosis
Describe how a cytotoxic T-cell induces apoptosis
- perforin makes pore in cell membrane
- granzyme B directly activates caspases
- apoptosis
