Pathophysiology of Chronic Inflammation

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Questions and Answers

What is the main characteristic of chronic nonspecific inflammation?

It has a characteristic histopathological pattern

It is a type of acute inflammation

It has no characteristic histopathological appearance (correct)

It is caused by persistent acute inflammation

Which of the following is an example of a non-infective granuloma?

Tuberculosis

Histoplasmosis

Silicosis (correct)

Leprosy

What is the main difference between acute and chronic inflammation in terms of onset?

Acute inflammation has a severe irritant, while chronic inflammation has a mild irritant

Acute inflammation has a gradual onset, while chronic inflammation has a sudden onset

Acute inflammation has a long duration, while chronic inflammation has a short duration

Acute inflammation has a sudden onset, while chronic inflammation has a gradual onset (correct)

What is the main characteristic of granulomatous inflammation?

It is characterized by focal accumulation of macrophages and lymphocytes Signup and view all the answers

What is the fate of granulomatous inflammation?

It heals by fibrosis with scar formation Signup and view all the answers

What is the main difference between regeneration and repair?

Regeneration is the replacement of destroyed tissue by the same cells, while repair is the replacement of damaged tissue by living tissue Signup and view all the answers

What is the main characteristic of chronic inflammation in terms of duration?

It has a long duration Signup and view all the answers

What is the main characteristic of acute inflammation in terms of local reactions?

It is characterized by thin-walled congested capillaries lined by swollen endothelium Signup and view all the answers

What type of cells have the ability to proliferate continuously to replace aging cells?

Labile cells Signup and view all the answers

What is the primary characteristic of granulation tissue?

It is red, granular, soft, and painless Signup and view all the answers

Which type of cells cannot proliferate at all?

Permanent cells Signup and view all the answers

What is the outcome of excess collagen deposition and obliteration of capillaries in granulation tissue?

Formation of scar tissue Signup and view all the answers

What is the characteristic of wounds that heal by primary intention?

Clean surgical wounds with minimal tissue destruction Signup and view all the answers

What is the next step after inflammation in the healing process by primary intention?

Epithelial changes Signup and view all the answers

What type of cells stimulate the ingrowth of fibroblasts and angioblasts in granulation tissue?

Macrophages Signup and view all the answers

What is the primary characteristic of healing by secondary intention?

Marked tissue destruction and bleeding Signup and view all the answers

Study Notes

Chronic Inflammation

Develops in 3 ways: on top of acute inflammation, repeated bouts of acute inflammation, or starts as chronic (e.g., T.B.)
Causes: persistent acute inflammation, infection by certain pathogens (e.g., T.B. bacilli), continuous exposure to irritant, impaction of foreign materials, autoimmune diseases, and diseases of unknown cause (e.g., inflammatory bowel disease)

Types of Chronic Inflammation

Chronic nonspecific inflammation: no characteristic histopathological appearance
Chronic specific inflammation: characteristic histopathological pattern (granulomatous inflammation)

Granulomatous Inflammation (Granuloma)

Definition: focal accumulation of macrophages (epithelioid cells) with lymphocytes, plasma cells, multinucleated giant cells, and fibroblasts
Types of granuloma:
- Infective granuloma: bacterial (e.g., T.B., leprosy), parasitic (e.g., bilharziasis, toxoplasma), and fungal (e.g., histoplasmosis)
- Non-infective granuloma: silicosis, asbestosis
- Foreign body granuloma: around foreign bodies (e.g., piece of wood, suture material)
Fate: heals by fibrosis with scar formation

Acute vs. Chronic Inflammation

Onset: acute (sudden), chronic (gradual)
Duration: acute (short), chronic (long)
Irritant: acute (severe), chronic (mild)
Local reactions:
- Acute: thin-walled congested capillaries, diffuse infiltration by acute inflammatory cells, fibrin threads, and coagulated fluid exudates
- Chronic: thick-walled blood vessels, perivascular infiltration by chronic inflammatory cells, and background of necrosis and progressive fibrosis
Systemic reactions: acute (marked), chronic (mild)

Repair

Definition: replacement of damaged tissue by living tissue
Types:
- Regeneration: replacement of destroyed tissue by the same cells (e.g., repair of bone fracture)
- Repair by fibrosis: replacement of destroyed tissue by granulation tissue which matures to fibrosis

Types of Cells

Labile cells: continuous proliferation to replace aging cells (e.g., stratified squamous epithelium of skin, columnar epithelium of GIT)
Stable cells: proliferate when needed (e.g., parenchymatous cells, mesenchymal cells)
Permanent cells: cannot proliferate at all (e.g., muscle cells, nerve cells)

Granulation Tissue

Definition: red, granular, soft, painless, and bleeds easily
Formation: in the gap of healing wounds, consisting of fibroblasts, collagen, newly formed blood vessels, and scattered macrophages and inflammatory cells
Fate: excess collagen deposition, obliteration of capillaries, and scar formation

Wound Healing

Healing by primary intention: clean surgical wounds, minimal tissue destruction, minimal bleeding, no bacterial infection, and good apposition of wound edges
Healing by secondary intention: gaping wounds, marked tissue destruction, bleeding, infection, and poor apposition of wound edges

Healing by Primary Intention

Initial hemorrhage: blood clot fills wound cavity
Inflammation (24 hours): PNL's infiltrate blood clot
Epithelial changes (48 hours): epithelial cells from wound edges proliferate
Early granulation tissue (3rd day): macrophages replace PNL's, stimulate ingrowth of fibroblasts and angioblasts, and form collagen type III

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Description

Learn about the development and causes of chronic inflammation, including the different types such as chronic nonspecific inflammation. Understand the role of pathogens, autoimmune diseases, and foreign materials in chronic inflammation.