Pathology for NEET-PG
Cell Injury and Inflammation for NEET-PG
Cell injury and inflammation form the general pathology foundation that underlies almost every disease process, and they are heavily tested in NEET-PG. This topic explains how cells respond to stress, when injury becomes irreversible, and how the body mounts acute and chronic inflammatory responses. Mastering it lets you reason through organ-specific pathology rather than memorising each disease separately. Examiners favour the reversible versus irreversible injury distinction, the morphological patterns of necrosis, the mediators of acute inflammation, and the cell types and outcomes of chronic inflammation and granulomas. Apoptosis pathways, free radical injury, and cellular adaptations such as hyperplasia and metaplasia are recurring points. The topic connects to immunology, microbiology, and every systemic pathology chapter. Common traps include confusing the necrosis patterns with their classic diseases, mixing up apoptosis with necrosis features, and forgetting which mediators drive vasodilatation, pain, and increased vascular permeability. A firm grasp here pays across the whole paper.
MedNext Academy | 3 min read
Cell Injury and Inflammation for NEET-PG
Cell injury and inflammation form the general pathology foundation that underlies almost every disease process, and they are heavily tested in NEET-PG. This topic explains how cells respond to stress, when injury becomes irreversible, and how the body mounts acute and chronic inflammatory responses. Mastering it lets you reason through organ-specific pathology rather than memorising each disease separately. Examiners favour the reversible versus irreversible injury distinction, the morphological patterns of necrosis, the mediators of acute inflammation, and the cell types and outcomes of chronic inflammation and granulomas. Apoptosis pathways, free radical injury, and cellular adaptations such as hyperplasia and metaplasia are recurring points. The topic connects to immunology, microbiology, and every systemic pathology chapter. Common traps include confusing the necrosis patterns with their classic diseases, mixing up apoptosis with necrosis features, and forgetting which mediators drive vasodilatation, pain, and increased vascular permeability. A firm grasp here pays across the whole paper.
Cell injury and inflammation form the general pathology foundation that underlies almost every disease process, and they are heavily tested in NEET-PG. This topic explains how cells respond to stress, when injury becomes irreversible, and how the body mounts acute and chronic inflammatory responses. Mastering it lets you reason through organ-specific pathology rather than memorising each disease separately. Examiners favour the reversible versus irreversible injury distinction, the morphological patterns of necrosis, the mediators of acute inflammation, and the cell types and outcomes of chronic inflammation and granulomas. Apoptosis pathways, free radical injury, and cellular adaptations such as hyperplasia and metaplasia are recurring points. The topic connects to immunology, microbiology, and every systemic pathology chapter. Common traps include confusing the necrosis patterns with their classic diseases, mixing up apoptosis with necrosis features, and forgetting which mediators drive vasodilatation, pain, and increased vascular permeability. A firm grasp here pays across the whole paper.
Key points
- **Reversible vs irreversible injury:** Membrane damage, severe mitochondrial dysfunction, and massive calcium influx mark the point of no return; cellular swelling is an early reversible change.
- **Coagulative necrosis:** Preserves tissue architecture and is typical of ischaemic infarcts in solid organs except the brain.
- **Liquefactive necrosis:** Seen in brain infarcts and bacterial abscesses due to enzymatic digestion of tissue.
- **Caseous necrosis:** Cheese-like appearance characteristic of tuberculosis and some fungal infections; a form of granulomatous inflammation.
- **Fat necrosis:** Occurs in acute pancreatitis and breast trauma, with calcium soap formation seen as saponification.
- **Apoptosis:** Programmed cell death without inflammation, using intrinsic mitochondrial and extrinsic death-receptor pathways with caspase activation.
- **Acute inflammation mediators:** Histamine and prostaglandins drive vasodilatation and permeability; bradykinin and prostaglandins mediate pain; leukotrienes drive chemotaxis.
- **Neutrophil vs mononuclear response:** Neutrophils dominate acute inflammation; lymphocytes, plasma cells, and macrophages dominate chronic inflammation.
- **Granuloma:** Collection of epithelioid macrophages with a rim of lymphocytes; caseating in tuberculosis and non-caseating in sarcoidosis.
- **Free radical injury:** Reactive oxygen species damage lipids, proteins, and DNA; antioxidants such as glutathione and superoxide dismutase are protective.
- **Cellular adaptations:** Hypertrophy, hyperplasia, atrophy, and metaplasia are reversible responses; dysplasia is a premalignant change.
Frequently Asked Questions
How do I remember the necrosis patterns?
Link each pattern to a classic disease: coagulative with myocardial infarct, liquefactive with brain infarct and abscess, caseous with tuberculosis, and fat necrosis with pancreatitis.
What distinguishes apoptosis from necrosis?
Apoptosis is programmed, energy-dependent, affects single cells, and does not incite inflammation. Necrosis is passive, affects groups of cells, and provokes an inflammatory response.
What is the difference between caseating and non-caseating granulomas?
Caseating granulomas show central necrosis and typify tuberculosis. Non-caseating granulomas lack central necrosis and are characteristic of sarcoidosis and Crohn disease.
Which mediators cause the cardinal signs of inflammation?
Histamine and prostaglandins cause redness, heat, and swelling through vasodilatation and permeability, while bradykinin and prostaglandins cause pain.
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