3. Cell Injury and Cell Death Flashcards
What is atrophy?
Decrease in the size or number of cells
What are the reasons for atrophy?
Decrease in workload Loss of innervation or blood supply Inadequate nutrition Loss of endocrine stimulation Ageing Physiologically in fetal development
What is hypertrophy?
Increase in the size of cells
Happens in permanent cells
Give 2 examples of hypertrophy
Skeletal muscle and exercise
Left ventricle and hypertension
What is hyperplasia?
Increase in the number of cells
Labile or stable cells
Give 2 examples of hyperplasia
Breast/uterus in response to hormones
Compensation in a partial hepatectomy
What is metaplasia?
Replacement of one adult epithelial type by another one
What parts of the cell are vulnerable to injury?
Mitochondria
Membrane
Ribosomes
DNA
What effect does damage to a mitochondria have?
Inhibition of aerobic respiration causes reduction in ATP
What does an increase in anaerobic respiration in reversible mitochondrial damage cause?
Reduction in Na+ pump, leading to accumulation of Na+ and water within the cell
What processes create free radicals?
Oxidative phosphorylation
Radiation
Inflammation
Drugs
What inactivates free radicals?
Enzymes
Antioxidants
How can free radicals injure the cell?
Lipid peroxidation of membranes
Damage enzymes
Mutate DNA
What cell changes are associated with reversible cell injury?
Swelling Bebbing of cell membrane Loss of microvilli ER dilates and ribosomes detach Nuclear alterations
What cell changes are associated with irreversible cell injury?
PM damage and enzyme release
Damage to mitochondrial and lysosome membranes
What is necrosis?
Enzymatic digestion of an injured cell and surrounding cells
ALWAYS associated with inflammation
What changes are seen in the cell in necrosis?
Cytoplasmic eosinophilia
Pkynosis
Karyorrhexis
Karyolysis
What is pyknosis?
Shrinking of nucleus
What is karyorrhexis?
Breaking up of nucleus
What is karyolysis?
Nucleus disappears
Where is coagulative necrosis seen?
Areas of hypoxia outside of the brain
What does coagulative necrosis look like?
Cell shape and organ structure are preserved
Nucleus disappears
What does liquefactive necrosis look like?
Liquid, complete digestion of cells by enzymes
What causes liquefactive necrosis?
Bacterial and fungal infection
Hypoxia in brain (lysosome rich)
What kind of infection causes caseous necrosis?
TB
What does caseous necrosis look like?
Crumbly, white
Granular debris surrounded by a ring of granulomatous inflammation
What happens in fat necrosis?
Fat is broken up by lipases
Ca++ soaps can be formed
What circumstances cause fat necrosis?
Fat trauma
Pancreatitis
What is fibroid necrosis?
Damage to a blood vessel wall
What circumstances does fibroid necrosis happen in?
Malignant hypertension and vasculitis
What type of necrosis is not actually necrosis?
Gangrenous
Name an anti-apoptotic gene
Bcl-2
Name a pro-apoptotic gene
Bax
Describe the process of apoptosis
Triggered by internal damage or external signals
Caspase cleaves proteins
Endonuclease fragments DNA
Phagocytosis of apoptotic bodies
What is dystrophic calcification?
Occurs when serum Ca++ is normal
Calcium is deposited in necrotic tissue
What is metastatic calcification?
Hypercalcaemia
Ca++ is deposited in normal tissue: vessels, kidneys, lungs, gastric mucosa
In the wear and tear theory of cell ageing, what is responsible?
Free radical damage throughout the cell’s life
In intrinsic cell ageing theory, what is responsible for cell ageing?
Telomere shortening
