Cell Injury Flashcards
Define hyperplasia. Give a physiological and pathological example.
increase in the number of cells
- physio: breast glands increase for lactation during pregnancy
- patho: high estrogen causes endometrial hyperplasia
Define hypertrophy. Give a physiological and pathological example.
increase in the size of cells
- physio: muscle size during weight lifting
- patho: HTN patients
Define atrophy. Give a physiological and pathological example.
decrease in cell size
- physio: low estrogen leading to post-menopausal decrease in endometrial growth
- patho: muscle atrophy
Define metaplasia. Give a physiological and pathological example.
cells change from one subset to another in response to stress/injury
- typically, trachea and esophagus are lined with simple columnar cells. cigarette smoking damages these cells and newly forming cells become stratified squamous cells better able to withstand cigarette smoke
List cellular adaptations.
- hyperplasia
- hypertrophy
- atrophy
- metaplasia
List vulnerable biochemical systems for cellular injury.
- membrane integrity
- mitochondrial aerobic respiration
- cellular calcium
- nuclear integrity
List biochemical changes that determine degree of reversible cell injury or cell death.
- ATP depletion
- reactive oxygen species
- loss of calcium homeostasis
- defective cell membrane permeability
Describe mechanism of injury via hypoxia.
Pathogenesis: decreased O2 => decreased oxidative phosphorylation => decreased ATP => impaired functioning of the Na/K pump => intracellular Na increases => water moves into the cell => swelling
Decreased ATP also => increase in cellular Ca => defective membrane permeability and activated enzymes (CK and LDH)
decreased ATP also => detached ribosomes => impaired protein synthesis => lipid deposition
End result = swelling
How can you test for hypoxic injury?
- measure levels of CK and troponin (for MI) as evidence of enzymatic leakage from swollen cells
- measure lactic acid levels as evidence of anaerobic respiration due to decreased ATP
What are defenses against ROS?
Vitamin C
Vitamin E
antioxidants
Describe mechanism of injury by ROS.
- lesions in DNA
- crosslinking of proteins
- oxidation of membranes
- mitochondrial damage
- reperfusion injuries
- metabolism of drugs (CCL3, acetominophen)
Describe mechanism of injury via loss of calcium homeostasis
- activation of cellular enzymes
phospholipases and proteases => membrane degradation
endonucleases => nuclear damage
ATPase => decreased ATP
List the morphological elements of reversible cellular injury.
- swelling
- steatosis (fatty changes)
- myelin
- ER swelling
- membrane blebs
List morphological characteristics of necrosis.
- presence of leukocytes (mainly neutrophils)
- increased eosinophilia (more pink due to denaturation of proteins
- nuclear structural changes (karyolysis, pyknosis, karyhorrhexis
- occurs in a geography of cells
What are structural changes that occur to the nucleus during necrosis?
- pyknosis: nuclear shrinkage, chromatin condensation
- karyorrhexis: fragmented pyknotic nucleus => nucleus disappeared
- karyolysis: loss of chromatin due to enzymatic degradation by endonucleases
