Inflammation & Immune Response Quiz

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Questions and Answers

What is one of the primary roles of interleukin-1 (IL-1) in inflammation?

It reduces blood flow to injury sites.

It recruits leukocytes to the site of inflammation. (correct)

It activates endothelial cells to promote the formation of new blood vessels.

It promotes apoptosis of tissue cells.

Which process describes the movement of plasma proteins and leukocytes from the circulation to an injury site?

Absorption

Exudation (correct)

Transudation

Osmosis

What differentiates exudate from transudate during an inflammatory reaction?

Exudate contains cellular debris. (correct)

Transudate is typically associated with infections.

Exudate has low protein content.

Transudate has high protein concentration.

Which of the following is NOT a component of acute inflammation?

Increased resistance in blood vessels. Signup and view all the answers

What triggers the activation of the inflammasome?

The binding of uric acid to receptors. Signup and view all the answers

Which of the following plays a role in promoting the ingestion of microbes?

Mannose-binding lectin Signup and view all the answers

Which of the following correctly describes acute inflammation?

It is a rapid response involving vasodilation and increased microvascular permeability. Signup and view all the answers

What role do collectins play in inflammation?

They bind to microbes and promote their phagocytosis. Signup and view all the answers

Which integrin is associated with Intercellular Adhesion Molecule-1 (ICAM-1)?

Leukocyte Function–Associated Antigen-1 (LFA-1) Signup and view all the answers

What is the primary site for leukocyte transmigration through the endothelium?

Postcapillary venules Signup and view all the answers

What mechanism drives leukocyte migration through the vessel wall?

Chemotaxis Signup and view all the answers

Which adhesion molecule is also known as CD31?

PECAM-1 Signup and view all the answers

What role does TNF and IL-1 play in the activation of endothelial cells?

Increase expression of ligands for integrins Signup and view all the answers

What occurs when leukocytes engage their integrins with ligands on the endothelium?

Leukocytes stop rolling and arrest Signup and view all the answers

What defines chemotaxis in leukocytes?

Locomotion along a chemical gradient Signup and view all the answers

How do leukocytes traverse the basement membrane after leaving the endothelium?

By secreting collagenases Signup and view all the answers

What is the process called when leukocytes move to the peripheral position along the endothelial surface due to decreasing wall shear stress?

Margination Signup and view all the answers

What is the primary action of histamine in the inflammatory response?

Vasodilation and increased vascular permeability Signup and view all the answers

What is the role of selectins in the interaction between leukocytes and endothelial cells?

To mediate initial weak interactions Signup and view all the answers

Which type of selectin is primarily expressed on endothelial cells?

E-selectin Signup and view all the answers

Cytokines like TNF and IL-1 primarily act locally by affecting which of the following?

Endothelial activation and expression of adhesion molecules Signup and view all the answers

What is a significant role of leukotrienes in inflammation?

Promoting chemotaxis and leukocyte adhesion Signup and view all the answers

What triggers leukocytes to change their integrins from a low-affinity form to a high-affinity form?

Presence of chemokines Signup and view all the answers

Which mediator is produced in the liver and plays a role in leukocyte chemotaxis?

Kinins Signup and view all the answers

What defines the interactions mediated by selectins on leukocytes?

Low-affinity and easily disrupted Signup and view all the answers

What is the primary source of platelet-activating factor during inflammation?

Leukocytes Signup and view all the answers

What is granulomatous inflammation characterized by?

Specific pattern of immune response Signup and view all the answers

Which component of the leukocyte adhesion process is responsible for firm adhesion to the endothelium?

Integrins Signup and view all the answers

How do leukocytes begin to roll along the endothelial surface?

Due to interactions with selectins Signup and view all the answers

Which condition may arise from unresolved acute inflammation?

Chronic lung abscess Signup and view all the answers

What effect does serotonin mainly have in inflammatory reactions?

Vasodilation and increased vascular permeability Signup and view all the answers

Which of the following statements about prostaglandins is correct?

They induce pain and fever. Signup and view all the answers

What happens to leukocytes as they roll along the endothelium?

They continually bind and detach. Signup and view all the answers

What primarily characterizes hypersensitivity diseases?

Excessive and inappropriate immune activation Signup and view all the answers

Which of the following contributes significantly to chronic inflammation?

Autoimmune reactions and prolonged exposure to irritants Signup and view all the answers

What is a major systemic effect of cytokines in inflammation?

Development of hypotension (shock) Signup and view all the answers

What role do macrophages play in chronic inflammation?

They secrete cytokines and growth factors to promote healing Signup and view all the answers

What is a morphological feature of chronic inflammation?

Formation of granulomas and fibrosis Signup and view all the answers

Which disease is considered an example of chronic inflammatory response due to excessive lipid deposition?

Atherosclerosis Signup and view all the answers

What inflammatory cell type is most dominant in chronic inflammatory reactions?

Macrophages Signup and view all the answers

Study Notes

### Inflammation & Immune Response

Inflammation is a complex response by the immune system to injury or infection.
Damaged Cells release molecules like uric acid, ATP, and DNA, which signal the immune system.
Inflammasomes are multiprotein complexes activated by these danger signals that trigger the production of the pro-inflammatory cytokine Interleukin-1 (IL-1).
IL-1 recruits leukocytes, leading to inflammation.
Circulating proteins, such as complement proteins, mannan-binding lectin, and collectins, recognize microbes and contribute to inflammation.

### Acute Inflammation

Three components:
- Dilation of small blood vessels, increasing blood flow
- Increased permeability of microvasculature, allowing plasma proteins and leukocytes to leave the circulation & enter tissue
- Emigration of leukocytes from the circulation, accumulation at the site of injury, and activation to eliminate the offending agent.

### Vascular Reactions in Acute Inflammation

Changes in blood flow and permeability: designed to maximize movement of plasma proteins and leukocytes from circulation to the site of infection or injury, a process known as exudation.
Exudate: Extravascular fluid with high protein concentration and cellular debris, indicating increased permeability of small blood vessels during inflammation
Transudate: Fluid with low protein content, little to no cellular material, and low specific gravity.
Margination: Leukocytes move closer to the vessel wall as blood flow slows, allowing them to detect changes in the endothelium.

### Leukocyte Adhesion

Selectins: Adhesion molecules expressed on leukocytes and endothelium, mediating weak, initial interactions.
- E-selectin: Expressed on endothelial cells
- P-selectin: Present on platelets and endothelium
- L-selectin: Found on the surface of most leukocytes.
Integrins: Transmembrane two-chain glycoproteins mediating firm adhesion of leukocytes to endothelium and various cells to the extracellular matrix.
- Initially expressed in a low-affinity form on leukocyte plasma membranes, activated by chemokines to adhere to specific ligands
- ICAM-1: Binds to integrins: LFA-1 and MAC-1
- VCAM-1: Binds to the integrin VLA-4
Chemokines are chemoattractant cytokines secreted by cells at sites of inflammation, activating leukocytes to change integrin conformation and increase affinity.

### Leukocyte Migration

Transmigration: Leukocytes migrate through the vessel wall, primarily by squeezing between endothelial cells at intercellular junctions. This process is known as diapedesis, and occurs mainly in post-capillary venules.
Chemotaxis: Leukocytes move towards the site of injury, following a chemical gradient created by chemokines.
PECAM-1: An adhesion molecule facilitating leukocyte traversal across the endothelium.

### Mediators of Inflammation

Vasactive amines: Histamine and serotonin
- Histamine causes dilation of arterioles and increases the permeability of venules
- Serotonin is a vasoactive mediator found in platelets and some neuroendocrine cells.
Lipid products: Prostaglandins and leukotrienes
- Prostaglandins: Vasodilation, pain, and fever
- Leukotrienes: Increased vascular permeability, chemotaxis, leukocyte adhesion, and activation
Cytokines: TNF, IL-1, and IL-6
- Local effects: Endothelial activation (expression of adhesion molecules)
- Systemic effects: Fever, metabolic abnormalities, hypotension (shock)
Chemokines: Chemotaxis and leukocyte activation
Platelet-activating factor: Vasodilation, increased vascular permeability, leukocyte adhesion, chemotaxis, degranulation, oxidative burst
Complement: Leukocyte chemotaxis and activation, direct target killing, vasodilation
Kinins: Increased vascular permeability, smooth muscle contraction

### Chronic Inflammation

Characterized by:
- Infiltration with mononuclear cells: Macrophages, lymphocytes, and plasma cells
- Tissue destruction, caused by persistent agents or inflammatory cells
- Attempts at healing: Connective tissue replacement of damaged tissue, angiogenesis (new blood vessel formation), and fibrosis.
Cells involved:
- Macrophages: Dominant cells in chronic inflammation, secreting cytokines and growth factors, destroying invaders and tissues, and activating lymphocytes.
- Lymphocytes: Immune cells that respond to specific antigens, contributing to chronic inflammation.

### Causes of Chronic Inflammation

Prolonged exposure to potentially toxic agents: Exogenous (e.g., silica) or endogenous (e.g., cholesterol)
Hypersensitivity diseases: Immune system overreactions
- Autoimmune diseases: Immune response attacks self-antigens, leading to chronic inflammation and tissue damage (e.g., rheumatoid arthritis)
- Allergic Diseases: Overreactions to common environmental substances (e.g., bronchial asthma)
Persistence of an infectious agent: Chronic infection by organisms that are difficult to eliminate (e.g., tuberculosis)
Certain cancers: Inflammation may promote tumor development.

### Key Takeaways

Inflammation involves a complex interplay of cells, chemical mediators, and vascular responses to eliminate harmful stimuli.
While acute inflammation is usually beneficial, chronic inflammation can lead to tissue damage and disease.
Understanding the mechanisms underlying inflammation is crucial for developing effective treatments for various inflammatory diseases.

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Description

Test your knowledge on the mechanisms of inflammation and the immune response. This quiz covers key concepts including inflammasomes, cytokines, and the components of acute inflammation. Understand how the body reacts to injury and infection.