Repair and fibrosis
How tissues heal after injury: when lost cells can be replaced like for like, how granulation tissue and collagen build a scar, and how repair that does not stop becomes fibrosis that stiffens organs.
By the end, you can
- Distinguish regeneration from repair and relate each to a tissue’s ability to divide.
- Describe granulation tissue and the sequence by which a wound becomes a scar.
- Explain how collagen is laid down, cross-linked and remodelled, and why scars are weaker than normal tissue.
- Explain how persistent injury leads to organ fibrosis and how fibrosis disturbs function in the liver, lung, heart and kidney.
- Relate deficient and excessive healing to their causes.
- Recognise the classic appearances of granulation tissue, scars and organ fibrosis, and explain how wound care, scar treatments and antifibrotic drugs act on repair.
What it is
Regeneration replaces lost cells with cells of the same type, restoring normal structure. Repair fills the defect with connective tissue, leaving a scar. Fibrosis is excess collagen laid down in an organ, usually during persistent injury or chronic inflammation, that replaces working tissue and distorts it.
2 types to tell apart
- Healing by first intention
- A clean wound with edges brought together: little granulation tissue and a thin scar.
- Healing by second intention
- A wide or infected wound left open: much granulation tissue, marked wound contraction and a larger scar.
US spelling: fibres → fibers.
Normal function
The scaffold that repair rebuilds
Most organs sit on a framework of connective tissue. In loose connective tissue, make for strength, for recoil and the that holds water; a supplies them. The basement membranes and fibres form a scaffold along which cells are arranged.
Cells differ in their ability to divide. Labile cells, such as surface epithelia and bone marrow, divide all the time. Stable cells, such as liver cells and kidney tubule cells, rest but can re-enter the cell cycle when needed. Permanent cells, such as most neurones and heart muscle cells, cannot usefully divide.
Underlying change · Step 1 of 5
Regeneration or repair?
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 2 of 5
Granulation tissue fills the gap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 5
Collagen, contraction and the scar
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 5
Fibrosis: repair that does not stop
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 5 of 5
When healing goes wrong
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .