Cell Injury Flashcards
If a cell can’t return to homeostasis, it tries to adapt by: 4 mechanisms
-hyperplasia
-hypertrophy
-metaplasia
-atrophy
Why is acute injury a problem?
lack of time to adapt
What are the 6 most vulnerable structures of a cell?
-mitochondria (site of ATP production)
-cell membrane and mitochondrial membrane (cell depends on for homeostasis)
-protein synthesis
-cytoskeleton
-genetic apparatus of the cell
-appendices: cilia, microvilli
Causes of cell injury
-hypoxia: ischemia, anemia, respiratory enzyme blockage
-physical agent: trauma, heat/cold, electricity
-infectious agents
-nutritional imbalance: deficiency or excess
-genetic derangement
-workload imbalance
-chemicals, drugs, toxins
-immune-mediated
-aging
Hypoxic cell injury: ischemia
-thrombosis/thromboembolism
-hypotension
Hypoxic cell injury: reduced circulation O2
-anemia
-carbon monoxide
-heart disease
Hypoxic cell injury: respiratory chain failure
-cyanide (attacks mitochondria)
Hypoxic cell injury: especially vulnerable cell populations
-neurons
-hepatocytes
-cardiac myocytes
-renal tubular epithelium
Cell injury: physical agents - trauma
crush, tear
Cell injury: physical agents - temperature
-heat coagulation
-ice crystals
Cell injury: physical agents - ionizing radiation
-thermal injury
-DNA damage
Cell injury: physical agents - electricity
-impaired pumps & signaling
-vascular injury: prepare for delayed fulminant pulmonary edema (ARDS)
Infectious agents: viruses
-hijack cell machinery
-lysis
Infectious agents: bacteria & fungi
-toxins
-suppurative vs macrophage-based inflammation
Infectious agents: protozoa
-direct cell infection
Infectious agents: parasites
-traumatic injury
-nutrient competition
Nutritional imbalance
-deficiency or excess can be harmful
-starvation or hypoglycemia
-obesity: metabolic demands, oxidative injury, inflammation
Nutritional imbalance: vitamins & minerals
-essential factors for critical enzymatic processes
-scavenging free radicals
-excesses can also cause problems
