As like every chapter this chapter’s cell injury and adaptation will also have its own notes and practice questions. There are 19 practice questions are added so far.
CELL INJURY AND ADAPTATION NOTES
When a cell is exposed to a range of stimuli as well as unfavourable environmental changes, two primary processes occurs, cell injury and adaptation.
Cell injury:
- Disease that occurs at a microscopic level in the human body
- Because tissues are not working normally
- Because of cell damage or inability to operate properly.
Cellular adaptation:
Cellular adaption refers to a cell’s capacity to respond to a variety of stimuli as well as unfavourable environmental changes.
- Atrophy,
- Hypertrophy,
- Hyperplasia,
- Dysplasia, and
- Metaplasia
Important things in Cell Injury and Adaptation:
1. NECROSIS
It is the morphological manifestation of end result of irreversible cell injury.
| S. No | Types of Necrosis | Cause | Morphology |
1 | Coagulative necrosis | Ischaemia | cellular outline preserved |
2 | Liquefactive necrosis | Infection and ischaemia of CNS | tissue turns into a viscous liquid |
| 3 | Caseous necrosis | T.B and systemic fungal infection | combination of coagulative and liquefactive necrosis(cheese-like) |
4 | Fat necrosis | Lipolysis | chalky white area |
| 5 | Fibrinoid necrosis | Ag-Ab complex deposition | the homogeneous pink stained area |
Apart from this there is another type of necrosis also called gangrenous necrosis,which is nothing but massive necrosis with superadded purefaction.
Gangenous necrosis is of 2 types:
- Dry gangrene – due to arterial occlusion
- Wet gangrene – due to venous occlusion
2. APOPTOSIS
Regulated mechanism of cell death that eliminate irreversibly damaged and unwanted cell,with least damage to the host.
Causes may be,
- Physiologic [embryogenesis] or
- Pathologic[viral infection]
Mechanism of Apoptosis
2 phases:
- Initiation phase
Intrinsic pathway-signal for apoptosis comes from inside cell itself
Extrinsic pathway-signal comes from outside cell
- Execution phase
execution phaeses is associated with cleavage of cellular elements
For animatic visual
3. Calcification
It is nothing but abnormal tissue deposition of calcium salts along with smaller amounts of Fe,Mg….
2 types:
- Dystrophic calcification- occurs in dead and degenerated tissues
- Metastatic calcification-occurs in nirmal tissues
4. ADDITIONAL NOTES
NECROPTOSIS:
It is a type of cell death that is morphologically necrosis but mechanically apoptosis.it is caspase-independent
PSAMMOMA BODIES:
They are concentric layers of calcium deposition mainly in necrotic areas, seen associated with papillary structures.
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