L4: Pathology of Cell Injury, Cell Death and Acute Inflammation

What are the main stimuli that can cause cell injury?

Hypoxia or anoxia, physical energy (heat), chemicals, biological agents, immune reactions, nutritional imbalance, and genetic defects.

What is the result of DNA damage in cell injury?

Abnormal protein formation, which can lead to apoptosis or cancer.

How does depletion of ATP contribute to cell injury?

Insufficient ATP disrupts cellular functions, leading to ion imbalance, cellular swelling, and eventual cell death.

What role do free radicals play in cell injury?

Free radicals cause damage to cellular components, including DNA, proteins, and lipids, leading to inflammation and cell death.

What are the consequences of cell membrane damage?

Influx of water and other materials, causing cellular swelling and lysis.

How does calcium influx contribute to cell injury?

Calcium activates harmful enzymes like phospholipase, protease, and endonuclease, leading to membrane and nuclear damage, and mitochondrial dysfunction.

What is hypertrophy, and provide an example.

Hypertrophy is the increase in cell size. An example is hypertrophic skeletal muscles in bodybuilders or hypertrophic smooth muscles of pregnant uterus

What is metaplasia, and provide an example.

Metaplasia is the change in cell phenotype. An example is columnar to squamous metaplasia in respiratory epithelial cells due to cigarette smoke.

What is hyperplasia, and provide an example

Hyperplasia is the increase in cell number. An example is breast tissue proliferation during pregnancy.

What is atrophy, and provide an example.

Atrophy is the decrease in cell number. An example is atrophic breast tissue in aging.

What occurs during reversible cell injury?

Characteristic changes like cellular swelling and fatty change that can revert to normal if the stimulus is removed.

What causes cellular edema in reversible cell injury?

Lack of ATP or cell membrane damage, leading to ion accumulation and water entry by osmosis.

What is fatty change, and what are its causes?

Fatty change is abnormal fat accumulation in cells, caused by hypoxia, toxins (e.g., alcohol), metabolic disorders (e.g., diabetes), or malnutrition.

What are the features of irreversible cell injury?

Severe or persistent injury leading to cell death, either through apoptosis or necrosis.

What is a key differentiator between apoptosis and necrosis?

Apoptosis is a programmed cell death affecting single cells, while necrosis involves the death of groups of cells and typically causes inflammation.

What are the cellular features of necrosis?

Karyolysis (nuclear fading), pyknosis (nuclear shrinkage), and karyorrhexis (nuclear fragmentation).

What is coagulative necrosis, and provide an example.

Coagulative necrosis is characterized by red/pink tissue due to inflammation. An example is acute myocardial infarction.

What is liquefactive necrosis, and provide an example.

Liquefactive necrosis involves the "liquefying" of dead cells by formation of pus or liquid mass. An example is dead brain cells in cerebral infarction (stroke).

What is caseous necrosis, and provide an example.

Caseous necrosis appears as "cream cheese-like" tissue. An example is lung tuberculosis with caseating granulomas.

What is fat necrosis, and provide an example.

Fat necrosis involves the formation of excess fatty acids. Enzymatic example: yellow "soap" formation in acute pancreatitis due to fatty acids reacting with calcium. Traumatic example: macrophages eating up leaked lipids by breast cells

What is fibrinoid necrosis, and where does it occur?

Fibrinoid necrosis involves the breakdown of blood vessel walls and fibrin activation, commonly seen in vasculitis.

What distinguishes irreversible from reversible cell injury?

Reversible injury is short-term and mild, while irreversible injury is severe or prolonged, leading to cell death.

What is the role of free radicals in cell injury mechanisms?

They can damage cellular components like DNA and proteins.

What are the methods to detect cell injury?

Electron microscopy and enzyme histochemistry (minutes to hours), light microscopy (hours to days), and gross examination (days to months).

What are the impacts of cell death on an organism?

Organ dysfunction, inflammation (if necrosis), scarring, and detectable molecules in blood tests.

What are the five types of necrosis

Coagulative, liquefactive, caseous, fat and fibrinoid necrosis.

What are the four types of tissue or cell adaptation upon stress?

hypertrophy, metaplasia, hyperplasia and atrophy