Lecture 7: Inflammation Overview

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Questions and Answers

What is the primary purpose of inflammation?

To facilitate digestion

To initiate the healing process (correct)

To supply nutrients to tissues

To increase body temperature

What does the term 'rubor' refer to in the context of inflammation?

Heat

Redness (correct)

Swelling

Pain

What is the first step in the process of phagocytosis?

Engulfment

Formation of phagolysosome

Recognition and attachment (correct)

Killing or degradation

Which of the following is not one of the cardinal signs of inflammation?

Immobility Signup and view all the answers

Which of the following is NOT an opsonin that enhances phagocytosis?

Major basic protein Signup and view all the answers

What occurs during the engulfment step of phagocytosis?

Formation of the phagosome Signup and view all the answers

Which mediator is primarily responsible for causing pain during inflammation?

Prostaglandins Signup and view all the answers

What would be a likely outcome if inflammation did not occur?

Permanent pus-forming sores Signup and view all the answers

Which of the following describes a method of oxygen-dependent killing in phagocytosis?

NADPH oxidase multiprotein enzyme complex Signup and view all the answers

Which type of inflammation is caused by foreign bodies?

Granulomatous inflammation Signup and view all the answers

What is formed when the phagosome fuses with the lysosome?

Phagolysosome Signup and view all the answers

What does 'tumor' indicate in the context of inflammation?

Swelling Signup and view all the answers

What is the effect of vasodilation in inflammation?

Increased blood flow Signup and view all the answers

What is the first major event in acute inflammation?

Vasodilation Signup and view all the answers

What primarily induces vasodilation during inflammation?

Histamine and nitric oxide Signup and view all the answers

Which event follows vasodilation in the inflammatory response?

Recruitment of leukocytes Signup and view all the answers

What defines the presence of edema during inflammation?

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

Which receptor is involved in the initial recognition of infectious agents in inflammation?

Fc receptors Signup and view all the answers

What causes increased permeability of microvessels during acute inflammation?

Histamine and kinins Signup and view all the answers

What is NOT a step in the inflammatory response?

Injury to adjacent tissues Signup and view all the answers

Which type of fluid is characterized by the presence of proteins and leukocytes?

Exudate Signup and view all the answers

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

Margination Signup and view all the answers

What proteins are primarily involved in the rolling of leukocytes?

Selectins Signup and view all the answers

Which leukocyte type is typically present in the early hours (6-24 hours) of an inflammatory response?

Neutrophils Signup and view all the answers

What is the role of chemotaxis in leukocyte extravasation?

To attract leukocytes to the site of injury Signup and view all the answers

Which molecule assists in the firm adhesion of leukocytes to endothelial cells during extravasation?

Integrins Signup and view all the answers

During transmigration, leukocytes cross through the endothelium by which mechanism?

Diapedesis Signup and view all the answers

What type of chemotactic agents can attract leukocytes to the site of injury?

Both endogenous and exogenous Signup and view all the answers

Which cytokine is known to act as a chemotactic factor for leukocytes?

IL-8 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 the acute inflammatory response.

What is Inflammation?

Inflammation is a protective response.
Key signs of inflammation (itis):
- Appendicitis: Inflammation of the appendix
- Gastritis: Inflammation of the stomach
- Arthritis: Inflammation of joints

Inflammation: Overview

Inflammation's primary goals:
- Remove the initial cause of cell injury (e.g., microbes, toxins).
- Remove the consequences of cell injury (e.g., necrotic cells and tissues).
- Initiate the process of repair.
Without inflammation:
- Infections could not be controlled.
- Wounds would not heal.
- Injured tissue would become persistent sores.

Cardinal Signs of Inflammation

Calor (Heat): Increased blood flow due to vasodilation. Mediators include histamine, prostaglandins, and bradykinin
Rubor (Redness): Increased blood flow due to vasodilation — also histamine, prostaglandins, and bradykinin.
Tumor (Swelling/Edema): Accumulation of fluid due to increased vascular permeability, and tissue damage. Histamine is responsible
Dolor (Pain): Release of chemicals that stimulate nerve endings (e.g., bradykinin and PGE2). Nerve endings are stimulated through increased pain/swelling.
Functio Laesa (Loss of Function): Increased pain/swelling, which causes loss of function.

Causes and Types of Inflammation

Causes:
- Infections (bacterial, viral, fungal, parasitic)
- Tissue necrosis (ischemia, physical/chemical injury, trauma)
- Foreign bodies (sutures, splinters, dirt)
- Immune reactions (hypersensitivity, autoimmune diseases)
Types:
- Acute inflammation
- Chronic inflammation
- Granulomatous inflammation

The Steps of Inflammatory Response

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

Acute Inflammation

4 Key Events:
- Vascular changes (vasodilation)
- Microvascular changes (increased vascular permeability)
- 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

Phagocytes, dendritic cells, and epithelial cells have pattern recognition receptors that detect infectious agents.
Examples: Toll-like receptors (TLRs), inflammasomes, Fc receptors, and complement system (lectin) recognize and bind to these substances.

I. Vascular Changes: Alteration in Vascular Flow and Caliber

Vasodilation is the earliest manifestation of inflammation—caused by histamine and nitric oxide.
Vasodilation increases blood flow to the site, leading to redness and warmth.
Increased hydrostatic pressure contributes to swelling (edema).

II. Microvascular Changes: Increased Permeability of Microvasculature

Increased permeability of blood vessels is a hallmark of acute inflammation.
Histamine, kinins, and other mediators cause gaps between endothelial cells, allowing plasma proteins and leukocytes to escape into the interstitial space.
Fluid leakage results in edema.

What is Edema?

Edema is the accumulation of excess fluid in interstitial tissues or body cavities. Two major types of edema are transudate and exudate, differentiated by protein content and inflammatory cell involvement

Differences between Transudate and Exudate

Transudate: Low protein content, low specific gravity (<1.020), results from hydrostatic imbalances, light straw color.
Exudate: High protein content, high specific gravity (>1.020), results from inflammation and injury, yellowish-white appearance.

III. Cellular Events: WBC Extravasation and Phagocytosis

Extravasation: Leukocytes migrate from blood vessels to the site of injury/infection. This involves several steps: margination, rolling, adhesion, transmigration, and chemotaxis.
Phagocytosis: Phagocytic cells (neutrophils, macrophages) engulf and destroy pathogens, necrotic cells, or foreign material. This process involves recognition and attachment, engulfment, and killing/degradation.

Step 5: Chemotaxis and WBC Activation

Transmigrated leukocytes move to the site of injury, guided by chemotactic agents.
Chemotactic agents can be exogenous (e.g., bacterial products) or endogenous (e.g., from the complement system or cytokines).
Different types of leukocytes will respond, depending on the type of stimulus (ex: neutrophils first, macrophages later).

Leukocyte Activation

Activation of leukocytes by various stimuli leads to production of arachidonic acid metabolites, secretion of lysosomal enzymes, degranulation, cytokine secretion, and modulation of cell adhesion molecules (CAMs).

Phagocytosis

This is the "process of engulfment".
Phagocytic cells (Neutrophils, Macrophages) engulf and degrade material/pathogens. Steps include recognition/attachment, engulfment, killing/degradation.
Oxygen-dependent killing uses NADPH oxidase complexes and other methods.
Oxygen-independent methods include lysozyme, lactoferrin, and other proteins.

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Description

This quiz explores the fundamental concepts of inflammation, including its definition and the acute inflammatory response. Students will learn about the signs of inflammation, its primary goals, and the importance of the inflammatory process in healing and disease management.