Cell Injury Part 2

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Questions and Answers

What is the primary cause of necrosis?

Controlled cellular signaling

Apoptotic pathways activation

Malfunction of membrane transport mechanisms

Enzymatic degradation of cellular components (correct)

Which of the following is NOT a characteristic of necrotic cells?

Intact membrane integrity (correct)

More homogeneous appearance

Increased eosinophilia

Vacuolated appearance

In which morphological feature does necrosis and apoptosis primarily differ?

Size of the dying cells

Cytoplasmic density

Vacuolization of the cytoplasm

Nuclear changes (correct)

What does increased eosinophilia in necrotic cells indicate?

Loss of RNA in the cytoplasm Signup and view all the answers

What does pyknosis in necrotic cells signify?

Nuclear shrinkage and increased basophilia Signup and view all the answers

Which nuclear change occurs due to the activity of deoxyribonucleases during necrosis?

Karyolysis Signup and view all the answers

What happens to the nucleus of a dead cell within 1 to 2 days?

It gradually disappears Signup and view all the answers

Which of the following best describes the morphological changes accompanying necrosis?

Acute and degenerative enzymatic actions Signup and view all the answers

What is the primary event that characterizes apoptosis?

Activation of caspases Signup and view all the answers

Which pathway of apoptosis is triggered by signals from plasma membrane receptors?

Death receptor pathway Signup and view all the answers

What role do cytotoxic T lymphocytes play in apoptosis?

Eliminate virus-infected cells Signup and view all the answers

In which scenario does apoptosis serve to prevent tissue destruction?

Self-reactive lymphocytes Signup and view all the answers

What is NOT a cause for apoptosis in pathologic conditions?

Capsule formation in bacteria Signup and view all the answers

What happens to the mitochondria during the mitochondrial pathway of apoptosis?

They become leaky Signup and view all the answers

Which of the following is a consequence of insufficient removal of cellular substances?

Abnormal intracellular accumulation Signup and view all the answers

What is the result of activated caspases in the apoptosis process?

Induction of cellular fragmentation Signup and view all the answers

What condition is characterized by the deposition of calcium salts in normal tissues?

Metastatic calcification Signup and view all the answers

Which of the following is NOT a cause of hypercalcemia?

Aging of heart valves Signup and view all the answers

Where does metastatic calcification typically occur in the body?

Interstitium of the kidney Signup and view all the answers

Which of the following statements about dystrophic calcification is true?

It can be found in areas of necrosis. Signup and view all the answers

What is the appearance of calcium deposits in dystrophic calcification at a microscopic level?

Basophilic deposits Signup and view all the answers

What is the primary mechanism through which fat necrosis occurs?

Activation of pancreatic lipases Signup and view all the answers

Which characteristic is NOT associated with apoptosis?

Membrane integrity loss Signup and view all the answers

What is produced when fatty acids combine with calcium during fat necrosis?

Chalky white areas Signup and view all the answers

In which physiological situation is apoptosis particularly important?

During organogenesis Signup and view all the answers

What microscopic feature is commonly seen in apoptotic cells?

Karyorrhexis Signup and view all the answers

What distinguishes necrosis from apoptosis?

Necrosis stimulates an inflammatory response Signup and view all the answers

Which type of necrosis is characterized by protein deposition and inflammation?

Fibrinoid necrosis Signup and view all the answers

What happens to the cellular contents during apoptosis?

They remain intact until phagocytosed Signup and view all the answers

What causes macrophages to develop a foamy appearance within atherosclerotic plaques?

Phagocytosis of lipid debris Signup and view all the answers

What type of cells accumulate intracellular cholesterol in xanthomas?

Foamy macrophages Signup and view all the answers

Which condition is typically associated with excessive glycogen accumulation?

Poorly controlled diabetes mellitus Signup and view all the answers

What is the primary cause of anthracosis?

Exposure to carbon particles Signup and view all the answers

What pathological process leads to the formation of xanthomas?

Hyperlipidemia and macrophage accumulation of cholesterol Signup and view all the answers

The degradation of which substances can lead to cell death in glycogen storage diseases?

Glycogen due to enzymatic defects Signup and view all the answers

What is one result of excessive intracellular cholesterol accumulation in macrophages?

Formation of atherosclerotic plaques Signup and view all the answers

What type of substances are pigments referred to in pathological context?

Only exogenous or endogenous colored substances Signup and view all the answers

Study Notes

Cell Injury: Necrosis and Apoptosis

Necrosis: Morphological changes due to cell death from enzyme degradation.
Necrotic cells lose membrane integrity, leaking cytoplasmic contents.
Enzymes from lysosomes of dying cells or recruited leukocytes cause necrosis.

Morphological Features of Necrosis

Cytoplasmic Changes: Increased eosinophilia (deep pink staining) due to denatured proteins and loss of RNA basophilia.
Nuclear Changes:
- Karyolysis: Fading basophilia of chromatin due to DNase activity.
- Pyknosis: Nuclear shrinkage and DNA condensation into solid mass.
- Karyorrhexis: Fragmentation of pyknotic nucleus; disappearance of nucleus within days.

Patterns of Necrosis

Caseous Necrosis: Characterized by cheese-like appearance; typically associated with tuberculosis.
Fat Necrosis: Seen in acute pancreatitis; pancreatic lipases digest fat tissue, leading to saponification and chalky white deposits.
Fibrinoid Necrosis: Involves protein deposition and inflammation within tissues.

Apoptosis

Defined as a regulated apoptotic program where cells activate enzymes to degrade internal components.
Unlike necrosis, apoptosis does not provoke an inflammatory response; cell membranes remain intact during fragmentation.

Microscopic Features of Apoptosis

Apoptotic cells often appear as round masses with eosinophilic cytoplasm.
Nuclear chromatin condenses, leading to fragmentation (karyorrhexis).
Apoptotic bodies form, which are phagocytosed quickly.

Causes of Apoptosis

Physiological Situations:
- Embryogenesis and organogenesis.
- Hormonal tissue regression (e.g., menstrual cycle, breast weaning, prostatic atrophy).
- Normal turnover in proliferating tissues (e.g., intestinal epithelium, neutrophils, lymphocytes).
Pathological Conditions:
- Targets genetically altered or irreparably damaged cells.
- Induced by DNA damage and accumulation of misfolded proteins.

Mechanism of Apoptosis

Key event: Activation of caspases leading to DNA degradation.
Two pathways:
- Mitochondrial Pathway: Triggered by loss of survival signals; involves Bcl-2 family proteins.
- Death Receptor Pathway: Signals from membrane receptors creating a death-inducing signaling complex activating caspases.

Cellular Accumulation

Abnormal accumulation of substances can be harmless or harmful, occurring in cytoplasm, nucleus, or organelles.
Pathways of accumulation include inadequate removal and defective transport.

Specific Accumulations

Cholesterol Accumulation:
- Macrophages ingest lipid debris, becoming foam cells in atherosclerosis.
- Xanthomas form in skin/connective tissues due to macrophage lipid accumulation.
Glycogen Accumulation:
- Seen in poorly controlled diabetes mellitus and glycogen storage diseases; results in significant intracellular deposits.
Pigments: Can be exogenous (e.g., carbon from air pollution) or endogenous (synthesized within body).
- Heavy accumulation may cause diseases like coal workers' pneumoconiosis.

Calcification

Dystrophic Calcification: Local calcium salt deposition due to tissue necrosis or damage (e.g., atherosclerosis, aging heart valves).
Metastatic Calcification: Widespread deposits in hypercalcemia cases, primarily affecting vessels, kidneys, lungs, and gastrointestinal tissues.

Causes of Hypercalcemia

Increased secretion of parathyroid hormone.
Bone destruction (e.g., Paget disease).
Vitamin D-related disorders.
Renal failure leading to phosphate retention and secondary hyperparathyroidism.

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Description

This quiz covers advanced topics related to cell injury, focusing on necrosis, apoptosis, and cellular accumulation. Students will explore the definitions, features, and mechanisms behind these processes as well as calcification causes. It is designed for the College of Medicine, University of Baghdad, for the academic year 2024-2025.

Cell Injury Part 2 - Grade 2