Lecture 2 Injuries to cells Flashcards
Define hyperplasia
Increase in number of cells.
Physiological example of hyperplasia?
Menstrual cycle
Pathological example of hyperplasia?
Endometrial hyperplasia if hormone stimulus persists
Define hypertrophy
Increase in the size of cells
Physiological example of hypertrophy?
Body builders
Pathological example of hypertrophy?
Heart in hypertension
Define Mataplasia
When one adult cell type is replaced by another adult cell trype
Example of metaplasia?
Chronic gastro-oesophageal reflux
Define atrophy
Shrinkage of cell size by loss of substance
Why atrophy happens?
↓ workload. ↓blood supply. Inadequate nutrition. ↓hormone stimulation. Ageing.
Morphology of reversible cellular injury?
Cellular swelling and fatty change.
Define necrosis
Damage to membrane allowing enzymes to digest cell.
Necrosis pathological or physiological
Always pathological
4 types of necrosis
Coagulation, liquefactive, caseous, fat.
Define apoptosis
Programmed cell death pathway. Both pathological and physiological.
How does apoptosis occur?
Cells activate enzymes that degrade cells own DNA and proteins -> death/deprived growth factors. Membrane remains intact, no leaks, phagocytosis removes bits of cell.
Physiological or pathological apoptosis? Embryogenesis
Physiological
Physiological or pathological apoptosis? Involution of hormone dependent tissues when deprived of hormone.
Physiological
Physiological or pathological apoptosis? Elimination of cells who have served their purpose.
Physiological
Physiological or pathological apoptosis? Killing ?harmful cells
Physiological
Physiological or pathological apoptosis? DNA damage
Pathological
Physiological or pathological apoptosis? Accumulation of misfolded proteins
Pathological
Physiological or pathological apoptosis? Atrophy in parenchymal organs after duct obstruction.
Pathological
Physiological or pathological apoptosis? Cell death induced by cytotoxic T cells
Pathological
Apoptosis results from the activation of
Caspases
Mitochondrial pathway…
Intrinsic pathway
Fas (death) receptor pathway…
Extrinsic pathway
Cell injury by ATP depletion
Occurs from: ↓oxygen and nutrient supply, mitochondrial damage, poisons. Effects: ATP dependent Na2+ pumps, ^lactic acid, Xcalcium pumps& protein damage.
Mitochondrial damage
Occurs from: hypoxia, chemical poisons, radiations. Effects: Fail to produce ATP & free radicals
Influx of Ca2+
Occurs from: ischaemia & poisons. Effects: ^intracellular Ca2+ -> enzyme activation -> damage to cellular components. APOPTOSIS.
Oxidative stress
Occurs from: ^free radicals. Removed by antioxidants. Effects: damage proteins, fat, DNA & create more of themselves.
DNA protein damage
Occurs from: radiation injury/oxidative stress. APOPTOSIS.
Defects in membrane permeability
Effects: ↓phospholipid synthesis (↓ATP). O2 free radicals and lipid breakdown. NECROSIS
Intracellular accumulation of abnormal material examples
Fat in hepatocytes (liver cells) from alcohol use. Cholesterol in SM in atherosclerosis. Protein in alzheimer’s and parkinson’s disease.
Damage to genes controlling DNA repair ->
susceptible to further change
Neoplastic
New growth
