AIM STEP 10
3rd Year MBBS
Pathology
3rd Year MBBS
Pathology
Student Memory Support
Tissue Healing, Regeneration and the Cell Cycle
High-yield memory reinforcement and last-minute KMU revision.
1. High-Yield Flashcards
Tap each question to reveal the answer.
What is regeneration?
Replacement of lost or damaged cells by cells of the same type, restoring tissue structure and function.
What mainly distinguishes repair from regeneration?
Repair restores tissue integrity mainly through connective tissue deposition and scar formation.
Which two factors strongly favor successful regeneration?
Proliferative capacity of surviving cells and preservation of the extracellular matrix framework.
What is granulation tissue composed of?
New capillaries, proliferating fibroblasts and loose extracellular matrix.
Which mediator is most strongly associated with angiogenesis?
VEGF.
Which mediator has a major role in extracellular matrix deposition and fibrosis?
TGF-β.
Which growth factor is particularly important for hepatocyte proliferation?
Hepatocyte growth factor, HGF.
How do labile cells behave?
They divide continuously and have strong regenerative capacity.
How do stable cells behave?
They are normally quiescent but can re-enter the cell cycle after appropriate stimulation.
Which important cells are considered permanent?
Neurons and cardiac muscle cells.
What are the main active phases of the cell cycle?
G1, S, G2 and M.
What happens during S phase?
DNA replication occurs.
What is the significance of G0?
It is a quiescent state outside the active cell cycle; stable cells may leave G0 after stimulation.
Which proteins are the main drivers of cell-cycle progression?
Cyclins and cyclin-dependent kinases, CDKs.
What is the role of p53 after DNA damage?
It can produce cell-cycle arrest, allowing time to deal with DNA damage before proliferation continues.
2. Mnemonics
Mnemonic Title: Cell-Cycle Sequence
“Grow, Synthesize, Get Ready, Mitosis”
Meaning: G1 → S → G2 → M.
Mnemonic Title: Proliferative Capacity
“Labile Live, Stable Sleep, Permanent Pause”
Meaning: Labile cells continuously divide; stable cells rest but can re-enter the cycle; permanent cells have very limited proliferation.
Mnemonic Title: Core Healing Progression
“Clean → Grow → Granulate → Collagen → Remodel”
Meaning: Inflammatory clearance → cell and vessel proliferation → granulation tissue → collagen deposition → scar remodeling.
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3. Memory Tables
Regeneration vs Repair
| Feature | Regeneration | Repair |
|---|---|---|
| Replacement | Same cell type | Connective tissue |
| Architecture | Can return toward normal | Scar replaces normal structure |
| Favored by | Viable proliferative cells + intact matrix | Severe injury or matrix destruction |
Labile vs Stable vs Permanent Cells
| Type | Baseline State | Regenerative Ability | Examples |
|---|---|---|---|
| Labile | Continuously dividing | High | Skin, intestinal epithelium, hematopoietic cells |
| Stable | Usually quiescent | Can proliferate after stimulation | Hepatocytes, renal tubular cells, fibroblasts, endothelial cells |
| Permanent | Terminally differentiated | Very limited | Neurons, cardiac myocytes |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- Regeneration restores lost cells with the same cell type; repair produces connective tissue and scar.
- Preserved extracellular matrix strongly favors organized regeneration.
- Granulation tissue contains new capillaries, fibroblasts and loose extracellular matrix.
- VEGF promotes angiogenesis during healing.
- TGF-β promotes extracellular matrix deposition and fibrosis.
- HGF is an important mediator of hepatocyte proliferation.
- Labile cells divide continuously; stable cells can re-enter the cycle after stimulation.
- Permanent cells such as neurons and cardiac myocytes have very limited proliferative capacity.
- S phase is the phase of DNA replication.
- Cyclins activate CDKs to drive orderly progression through the cell cycle.
- p53 can arrest the cell cycle when DNA is damaged.
Common KMU confusion: Granulation tissue is healing tissue rich in capillaries and fibroblasts; it is not a granuloma.
5. Clinical Memory Hooks
Superficial epithelial injury with intact framework
→
surviving cells proliferate
→
regeneration with minimal scar.
→
surviving cells proliferate
→
regeneration with minimal scar.
Deep wound with stromal destruction
→
fibroblast proliferation + collagen deposition
→
fibrous scar.
→
fibroblast proliferation + collagen deposition
→
fibrous scar.
Partial loss of liver tissue
→
quiescent hepatocytes re-enter the cell cycle
→
restoration of liver mass.
→
quiescent hepatocytes re-enter the cell cycle
→
restoration of liver mass.
Large myocardial injury
→
cardiac myocytes have very limited proliferative capacity
→
healing mainly by scar.
→
cardiac myocytes have very limited proliferative capacity
→
healing mainly by scar.
6. Starred High-Yield Exam Points
- ⭐ Intact extracellular matrix + proliferative cells strongly favor regeneration.
- ⭐ Granulation tissue = new capillaries + fibroblasts + loose extracellular matrix.
- ⭐ VEGF drives angiogenesis; TGF-β promotes matrix deposition and fibrosis.
- ⭐ Labile cells continuously divide; stable cells can re-enter the cycle; permanent cells have very limited division.
- ⭐ G1 prepares for DNA synthesis, S replicates DNA, G2 prepares for mitosis, and M produces daughter cells.
- ⭐ Cyclin D–CDK4/6 supports early G1; cyclin E–CDK2 supports G1/S progression; cyclin B–CDK1 promotes mitosis.
- ⭐ p53-mediated cell-cycle arrest protects against progression when DNA damage is present.