Lecture 7: Inflammation Overview

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary purpose of inflammation?

To initiate fever

To inhibit blood flow

To respond protectively to injury (correct)

To create permanent scars

Which of the following is NOT a cardinal sign of inflammation?

Pain

Heat

Fever (correct)

Swelling

What causes the redness associated with inflammation?

Decreased blood flow

Vasodilation and increased blood flow (correct)

Chemical irritation of the nerves

Fluid accumulation

Which mediator is responsible for the pain experienced during inflammation?

All of the above Signup and view all the answers

What does tumor refer to in the context of inflammation?

Swelling Signup and view all the answers

What is a potential consequence if inflammation does not occur?

Increased infections Signup and view all the answers

Which type of inflammation is caused by physical injury?

Acute inflammation Signup and view all the answers

What role do prostaglandins play in inflammation?

Stimulate nerve endings to trigger pain Signup and view all the answers

What is the first step in the process of phagocytosis?

Recognition and attachment Signup and view all the answers

Which component enhances the recognition and attachment of microorganisms by phagocytic cells?

Opsonins Signup and view all the answers

What forms when the plasma membrane of a phagocyte pinches off during engulfment?

Phagosome Signup and view all the answers

Which of the following is NOT involved in oxygen-independent killing mechanisms during phagocytosis?

NADPH oxidase Signup and view all the answers

What role do acid hydrolases play in the phagocytosis process?

Degrading ingested materials Signup and view all the answers

What is the first major event in acute inflammation?

Vascular Changes Signup and view all the answers

Which of the following best describes edema?

Accumulation of excess fluid in interstitial tissue Signup and view all the answers

What triggers vasodilation during the acute inflammatory response?

Histamine and nitric oxide Signup and view all the answers

Which component is NOT part of the cellular events in acute inflammation?

Accumulation of plasma proteins Signup and view all the answers

What is the purpose of pattern recognition receptors in immune response?

To recognize foreign substances and microbes Signup and view all the answers

What causes the increased permeability of microvasculature in acute inflammation?

Histamine and kinins Signup and view all the answers

Which of these is a consequence of the recruitment of leukocytes during acute inflammation?

Leukocyte emigration to the tissue site Signup and view all the answers

What phase follows the removal of the offending agent in the inflammatory response?

Regulation of the reaction Signup and view all the answers

What is the first step in the process of leukocyte extravasation?

Margination Signup and view all the answers

Which type of cell is involved in the Rolling step of extravasation?

Neutrophils Signup and view all the answers

What mediates the adhesion of leukocytes to endothelial cells during extravasation?

Integrins Signup and view all the answers

What is the role of chemotactic agents in leukocyte activation?

Mobilizing leukocytes to the site of injury Signup and view all the answers

What is the primary type of leukocyte that emigrates within the first 6-24 hours of an inflammatory response?

Neutrophils Signup and view all the answers

What facilitates the transmigration of leukocytes across the endothelium?

PECAM-1 Signup and view all the answers

Which of the following can act as a chemotactic agent?

Leukotrienes Signup and view all the answers

What is a common result of leukocyte activation during the inflammatory process?

Production of Arachidonic acid metabolites Signup and view all the answers

Study Notes

Lecture 7: Inflammation: Introduction & Acute Inflammation

Learning Outcomes: Students will be able to define inflammation and discuss the events and components of an acute inflammatory response.

What is Inflammation?

Inflammation is an inflammatory response to tissue injury.
Types of inflammation resulting in inflammation include: appendicitis (appendix inflammation), gastritis (stomach inflammation), and arthritis (joint inflammation).

Inflammation: Overview

Inflammation is a protective response.
Its goals are to eliminate the initial cause of injury (e.g., bacteria, toxins), the consequences of cell injury (e.g., necrotic cells), and initiate the repair process.
Without inflammation, infections would not be controlled, wounds would never heal, and injured tissue would remain open sores.

Cardinal Signs of Inflammation

Calor (Heat): Due to vasodilation (increased blood flow) from histamine, prostaglandins, and bradykinin.
Rubor (Redness): Increased blood flow.
Tumor (Swelling/Edema): Fluid accumulation due to increased permeability and tissue damage, especially from histamine, tissue damage.
Dolor (Pain): Release of chemicals (e.g., bradykinin and PGE2) which stimulate nerve endings.
Functio Laesa (Loss of Function): Increased pain and swelling.

Causes and Types of Inflammation

Infections: Bacterial, viral, fungal, parasitic.
Tissue Necrosis: Ischemia (lack of blood supply), physical/chemical injury, trauma.
Foreign Bodies: Sutures, splinters, dirt.
Immune Reactions: Hypersensitivity, autoimmune diseases.
Types:
- Acute inflammation (initial response)
- Chronic inflammation (long-term response)
- Granulomatous inflammation (a type of chronic inflammation)

The Steps of Inflammatory Response

Recognition: Host cells recognize the offending agent.
Recruitment: Leukocytes and plasma proteins move to the site of injury.
Removal: Activated leukocytes eliminate the offending agent.
Regulation: Termination of the response.
Repair: Damaged tissue is repaired.

Acute Inflammation

Vascular Changes: Vasodilation (increased blood flow).
Microvascular Changes: Increased vascular permeability (plasma proteins and white blood cell leakage).
Cellular Events: WBC emigration, accumulation, and activation at the site of injury.
Chemical Mediators: Derived from plasma proteins and cells.

Recognition of Microbes, Necrotic Cells, and Foreign Substances

Danger signals are triggered from microbes and dead cells.
Phagocytes, dendritic cells, and epithelial cells express pattern recognition receptors that recognize infectious agents.
- Examples include: toll-like receptors (TLRs), inflammasomes, Fc receptors, and the complement system (lectin).

I. Vascular Changes: Alteration in Vascular Flow and Caliber

Earliest manifestation is vasodilation, which is induced by histamine and nitric oxide.
Vasodilation leads to increased blood flow resulting in redness (rubor) and heat (color).

II. Microvascular Changes: Increased Permeability of Microvasculature

A hallmark of acute inflammation.
Caused by histamine, kinins, and other mediators.
Increased gaps between endothelial cells lead to increased vascular permeability, allowing plasma proteins and leukocytes to escape and enter sites of infection/injury.
Fluid leak results in edema (swelling).

What is Edema?

Edema is the accumulation of excess fluid in interstitial tissues or serous cavities.
- It's classified into transudate (low protein) and exudate (high protein).

Differences between Transudate and Exudate

Transudate: Low protein content, low specific gravity (<1.020), result from hydrostatic imbalance, light straw color.
Exudate: High protein content, high specific gravity (>1.020), result from inflammation/injury, yellowish-white colored.

III. Cellular Events: WBC Extravasation and Phagocytosis

WBCs migrate to the site of injury and exit blood vessels, a process called extravasation.
Extravasation steps include margination, rolling, adhesion, transmigration, and chemotaxis.

Step 5: Chemotaxis and WBC Activation

Transmigrated leukocytes migrate to sites of injury along chemotactic gradients.
Chemotactic agents can be exogenous or endogenous.
Examples include soluble bacterial products, components of the complement system (e.g. C5a), and cytokines (e.g IL-8, leukotrienes).
Leukocyte type varies depending on the stimulus and age of the inflammatory response (e.g., neutrophils in early stages, macrophages later).

Leukocyte Activation

Activated by microbes, necrotic cells, antigen-antibody complexes, and chemotactic factors.
Activation results in production of arachidonic acid metabolites, secretion of lysosomal enzymes, degranulation, cytokine secretion, and modulation of cell adhesion molecules (CAMs).

Phagocytosis

Process of engulfing and eliminating solid particles (e.g., bacteria, necrotic tissue, foreign material) by phagocytic cells (e.g., neutrophils, macrophages).
Three stages: Recognition/attachment, engulfment (phagosome formation), killing/degradation (phagolysosome formation).
- Killing/degradation uses both oxygen-dependent and oxygen-independent mechanisms.

References

Robbins and Cotran Pathologic Basis of Disease, 10th ed. (2021)
Harsh Mohan Textbook of Pathology, 7th ed.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz focuses on the introduction and acute inflammation as discussed in Lecture 7. Students will explore the definition of inflammation, its types, and the cardinal signs that characterize the inflammatory response. Understanding these concepts is crucial for comprehending how the body reacts to injury and infection.