Serous, fibrinous and catarrhal inflammation
Why inflamed tissue leaks thin serous fluid, sticky fibrin or mucus-laden catarrh: how vessel injury and the surface involved decide which, what each looks like, and how each clears or scars.
By the end, you can
- Explain how the severity of endothelial injury decides what an exudate contains.
- Distinguish an exudate from a transudate by its protein and cell content.
- Describe serous inflammation, its typical sites and why it usually leaves no trace.
- Describe fibrinous inflammation on serous membranes, in the lung and on mucosae (croupous and diphtheritic membranes), and why it can organise into adhesions.
- Describe catarrhal inflammation of mucous membranes and how it progresses.
- Recognise the classic appearances, types and tests of exudates, including Light’s criteria, and explain how drainage, anti-inflammatory drugs, antitoxin and surgery act on them.
What it is
Exudative inflammation is named by what dominates the fluid that leaves the vessels. In serous inflammation it is a thin, protein-rich fluid with few cells; in fibrinous inflammation, larger leaks let fibrinogen out to form fibrin on surfaces; in catarrhal inflammation of a mucous membrane, the exudate mixes with mucus and flows off the surface. Purulent and haemorrhagic exudates have their own lessons, and mixed forms (serofibrinous, mucopurulent) are common.
4 types to tell apart
- Serous inflammation
- Thin, clear or straw-coloured fluid rich in albumin: blisters, effusions in the pleura, pericardium, peritoneum or joints, and the early stage of most inflammations.
- Fibrinous inflammation
- Fibrinogen leaks and polymerises to fibrin: on serous membranes (fibrinous pericarditis, pleurisy), in the alveoli of lobar pneumonia, and as membranes on mucosae.
- Croupous and diphtheritic membranes
- Fibrinous membranes on mucosae: croupous lies loosely on the surface (trachea, bronchi) and peels off; diphtheritic is bound into deeper necrosis (tonsils, pharynx) and tears the surface when removed.
- Catarrhal inflammation
- Inflammation of a mucous membrane with exudate mixed into mucus that drains off the surface: serous, then mucous, then mucopurulent; acute (a cold) or chronic (chronic bronchitis).
US spelling: haemorrhagic → hemorrhagic.
Normal function
Vessels hold protein in; surfaces glide
Fluid crosses the capillary wall all the time, but the endothelium and its basement membrane hold back most plasma protein and all cells. The little fluid that leaves is low in protein, and lymphatics return it to the blood.
Exudates collect on surfaces. A serous membrane, such as the , is a sheet of flat mesothelial cells on connective tissue; its parietal layer and the glide over each other on a thin film of fluid in the . The pleura and peritoneum are built the same way.
A mucous membrane, lining the airways and gut, is an epithelium with goblet cells and glands that make mucus, on a vascular lamina propria. Whether the exudate lands on a serous or a mucous surface shapes what it looks like.
Underlying change · Step 1 of 5
What leaks depends on how badly vessels are injured
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 2 of 5
Serous inflammation: thin, protein-rich fluid
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
Fibrinous inflammation: fibrin on surfaces
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 4 of 5
Catarrhal inflammation: mucous membranes
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
How exudates clear or organise
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 .