Inflammation Overview and Cardinal Signs

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Questions and Answers

What is the primary function of tissue macrophages during the inflammatory response?

To promote vasodilation

To phagocytize invading microbes (correct)

To increase capillary permeability

To release histamine

What mainly causes localized vasodilation during the inflammatory response?

Increased production of cytokines

Leakage of plasma proteins

Phagocytosis of microbes by macrophages

Histamine released from activated mast cells (correct)

How does increased capillary permeability affect the affected area during inflammation?

It enhances the communicative signals to surrounding tissues

It reduces blood flow and oxygen delivery

It initiates vasoconstriction in the area

It causes fluid and plasma proteins to leak into tissues (correct)

What are the cardinal signs of inflammation, excluding pain?

Redness, swelling, heat, loss of function Signup and view all the answers

What is the role of bradykinin during the inflammatory response?

It increases capillary permeability and vasodilation Signup and view all the answers

Which step is NOT typically involved in the inflammatory response?

Localized contraction of blood vessels Signup and view all the answers

What effect does localized edema have in the context of inflammation?

It facilitates the movement of phagocytes to the affected area Signup and view all the answers

Which of the following accurately describes the role of cyclooxygenase (COX) in the body?

COX primarily facilitates the conversion of arachidonic acid into prostaglandins. Signup and view all the answers

What is the primary function of leukotrienes produced by lipoxygenase (LOX)?

Enhancing inflammation and causing bronchoconstriction. Signup and view all the answers

How do corticosteroids modulate the inflammatory response in the body?

By inhibiting the release of arachidonic acid from cell membranes. Signup and view all the answers

Which of the following cytokines is primarily associated with attracting leukocytes through chemotaxis?

Interleukin-1 (IL-1) Signup and view all the answers

Which function does interferon-beta (IFN-β) primarily serve during a viral infection?

Protecting uninfected cells from viral infection. Signup and view all the answers

What role does C3b play in the phagocytosis of bacteria?

It creates a linkage between bacteria and phagocytes. Signup and view all the answers

Which type of phagocyte is known to engulf the most bacteria before succumbing to destructive enzymes?

Macrophages Signup and view all the answers

What is a major side effect of inhibiting COX-1 when using NSAIDs?

Gastric ulcers Signup and view all the answers

What type of vesicle is formed during phagocytosis?

Endocytic vesicle Signup and view all the answers

Which class of drugs primarily inhibits cyclooxygenase to reduce inflammation?

Nonsteroidal anti-inflammatory drugs (NSAIDs) Signup and view all the answers

What constitutes pus found in an infected wound?

Living and dead phagocytes, necrotic tissue, and bacteria Signup and view all the answers

What is the prototype drug in the NSAID class?

Aspirin Signup and view all the answers

Which of the following selective COX-2 inhibitors is no longer on the market?

Rofecoxib Signup and view all the answers

What happens to the enzymes that escape from the lysosome during phagocytosis?

They can kill the phagocyte itself. Signup and view all the answers

What is a primary effect of glucocorticoids on the immune response?

Decreasing the release of inflammatory mediators Signup and view all the answers

How do mast cells contribute to the inflammatory response?

By releasing granules filled with inflammatory mediators Signup and view all the answers

What effect does the increase in interstitial fluid colloid osmotic pressure (πi) have on fluid movement?

Fluid moves out of the capillaries and into the tissue spaces. Signup and view all the answers

Which of the following substances is NOT a direct effect of histamine?

Bronchial smooth muscle relaxation Signup and view all the answers

What is a significant risk associated with the use of glucocorticoids?

Increased risk of infection Signup and view all the answers

Which cells arrive first at an injury site to initiate phagocytosis?

Neutrophils Signup and view all the answers

Which of the following describes the process of diapedesis?

Phagocytes squeeze through capillary pores to enter tissue. Signup and view all the answers

Which inflammatory mediators are derived from arachidonic acid?

Prostaglandins and leukotrienes Signup and view all the answers

What initiates the formation of clots within the tissue spaces during inflammation?

The activation of fibrinogen to fibrin. Signup and view all the answers

What is the main function of the chemotactic factors released by activated mast cells?

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

Opsonization serves which primary purpose in the immune response?

To mark bacteria for phagocytosis. Signup and view all the answers

What effect does glucocorticoid administration have on T cells?

Decreases T cell activation Signup and view all the answers

What factor primarily facilitates the increased numbers of phagocytes at the site of injury?

Increased capillary permeability. Signup and view all the answers

Which of the following is a role of nitric oxide in inflammatory response?

Enhancing blood flow and oxygen delivery Signup and view all the answers

Which component is NOT involved in marking bacteria for phagocytosis?

Fibrinogen Signup and view all the answers

What do glucocorticoids primarily reduce in the context of inflammation?

Symptoms but not underlying causes Signup and view all the answers

What is the last step in the emigration process of phagocytes toward an injury?

Chemotaxis Signup and view all the answers

Which cytokine is NOT mentioned as part of inflammatory mediators in the content?

Chemokines Signup and view all the answers

What occurs when anticlotting factors dissolve the clots formed in tissue spaces?

Inflammation subsides and healing begins. Signup and view all the answers

Study Notes

Inflammation is a vital physiological process that occurs in response to harmful stimuli such as pathogens, damaged cells, or irritants. This complex protective mechanism is characterized by a series of biological events, including the activation of various immune cells, blood vessels, and molecular mediators. The process not only helps to contain and eliminate the initial cause of cell injury but also plays a crucial role in initiating tissue repair and healing.

During inflammation, the body experiences several classic symptoms, which include redness (due to increased blood flow), heat, swelling (resulting from the accumulation of fluid and immune cells), pain (as a consequence of the release of inflammatory mediators), and loss of function in the affected area. These symptoms reflect the body's attempt to restore homeostasis and promote healing.

One of the key components of inflammation is the recruitment of phagocytic cells, such as neutrophils and macrophages, which work to engulf and destroy invading pathogens or dead cells. Additionally, plasma proteins, including antibodies and clotting factors, accumulate at the site of injury to facilitate the immune response and repair processes. Overall, while inflammation is essential for defending the body against threats, chronic inflammation can lead to tissue damage and contribute to a range of diseases, including autoimmune disorders, cardiovascular diseases, and cancer.

Overview

Inflammation is a complex, multi-step reaction.
It involves the accumulation of phagocytes and plasma proteins at sites of infection, toxin exposure, or tissue injury.
Its purpose is to:
- Isolate, destroy, or inactivate infectious microbes.
- Remove tissue debris.
- Promote tissue repair.

Cardinal Signs of Inflammation

Rubor (Redness): Increased blood flow to the affected area.
Tumor (Swelling): Increased capillary permeability and fluid accumulation.
Calor (Heat): Increased temperature due to increased blood flow.
Dolor (Pain): Altered or impaired function of the affected area.
Functio laesa (Loss of Function): Impaired function of the affected area.

Steps in the Inflammatory Response

Plasma-derived mediators: Released from the liver. Examples include acute-phase proteins, Factor XII (Hageman factor) activation, complement proteins, clotting/fibrinolytic system, and kinin system (
- Bradykinin: Bradykinin is a potent vasoactive peptide that plays a critical role in the inflammatory response. It is formed from the cleavage of kininogen, a precursor protein, by the action of the enzyme kallikrein. Once released at the site of injury or inflammation, bradykinin acts on blood vessels to induce vasodilation, leading to increased blood flow and contributing to the cardinal sign of redness. Additionally, it enhances vascular permeability, allowing plasma proteins and leukocytes to migrate to the inflamed tissue, which facilitates the healing process. Furthermore, bradykinin is involved in pain signaling, as it sensitizes nerve endings and contributes to the sensation of pain (dolor). Its actions are transient and are modulated by various enzymes in the tissue that degrade bradykinin, ensuring a balanced inflammatory response.
).
Cell-derived mediators: Released from various cells. Examples include preformed mediators (histamine from mast cells, serotonin from platelets, lysosomal enzymes from neutrophils), and newly synthesized mediators (prostaglandins, leukotrienes, platelet-activating factor, nitric oxide, cytokines from various cells).

Defense by Tissue Macrophages

Macrophages are present in tissues, providing initial protection against infection by phagocytizing invading microbes.

Localized Vasodilation

Vasodilation of arterioles increases blood flow to the affected area.
This process is primarily caused by histamine from mast cells and activated bradykinin.
Mast cells are located in connective tissues, especially areas like lungs, skin, and gastrointestinal tract.
Vasodilation results in redness and heat.

Increased Capillary Permeability

Histamine and bradykinin increase the size of pores between endothelial cells.
This leads to increased capillary permeability, allowing plasma proteins to move into tissue spaces.

Localized Edema

Vasodilation and increased capillary permeability lead to localized edema.
Increased blood flow increases capillary pressure (Pc).
Escaped plasma proteins increase interstitial fluid colloid osmotic pressure (πi).
Fluid moves from capillaries to the tissue.
Edema symptoms include swelling and pain due to tissue distension.

Walling-Off the Inflamed Area

Clotting and anti-clotting factors escape into the tissue space.
Fibrinogen converts to fibrin, forming clots within the tissue.
This effectively isolates the injured area and prevents the spread of infection.
Anti-clotting factors later dissolve clots when no longer needed.

Infiltration of Phagocytes

Increased numbers of phagocytes are needed to remove infectious microbes, debris, and prepare the injured area for healing.
Neutrophils arrive first, typically within 1 hour.
Monocytes arrive within 8–12 hours and transform into macrophages.
Phagocytes emigration involves three steps: margination, diapedesis, and chemotaxis.

Opsonization

Opsonization is the process of marking bacteria for phagocytosis.
Opsonins, such as antibodies and complement protein C3b, bind to bacteria and mark them.
The higher concentration of C3b is due to the increased permeability of capillaries and plasma protein leakage.
C3b binds to bacteria and receptors on phagocytes, preventing bacterial escape.

Phagocytosis

Phagocytosis is the process of ingestion and digestion of bacteria, foreign particles, and tissue debris.
The phagocyte's plasma membrane engulfs substances in a process called endocytosis, forming an endocytic vesicle.
The vesicle fuses with a lysosome (containing hydrolytic enzymes), forming a phagolysosome.
The lysosomal enzymes degrade the engulfed material.
Phagocytes, such as neutrophils and macrophages, engulf and destroy microbes.

Inflammatory Mediators

Histamine and mast cells: Release histamine in response to various stimuli, leading to vasodilation, increased vascular permeability, and bronchoconstriction. Mast cells contain granules with other inflammatory mediators, including chemotactic factors for neutrophils and eosinophils, cytokines, prostaglandins, leukotrienes, and platelet-activating factor.
Prostaglandins and leukotrienes: derived from arachidonic acid. Prostaglandins enhance inflammation, contract smooth muscle, increase capillary permeability, cause vasodilation, and act as pyrogens. Leukotrienes also enhance inflammation, increase vascular permeability, and cause vasodilation; they are bronchoconstrictors.
Cytokines: small proteins produced by various cell types. Examples include interleukins (ILs), interferons (IFNs), and tumor necrosis factor-alpha (TNF-α).
Chemokines: small peptides that act as chemotactic substances for immune cells.
Nitric oxide (NO): produced by vascular endothelium. NO causes vasodilation and acts as a mediator of inflammation, inhibiting leukocyte aggregation, platelet adhesion, and cytokine release.

Fever

Fever is a systemic response to inflammation or infection.
Endogenous pyrogens (such as cytokines and prostaglandins) and exogenous pyrogens (bacteria and bacterial toxins) raise body temperature.
Fever may impair the activity of infectious microorganisms or their toxins.

Anti-inflammatory Drugs

In some cases inflammation can be inappropriate or exaggerated.
Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, and naproxen, inhibit cyclooxygenase (COX) enzyme.
This leads to reducing prostaglandin synthesis.
Corticosteroids inhibit the release of arachidonic acid. This reduces inflammatory mediators.

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Description

This quiz covers the complex process of inflammation, detailing its purpose and the cardinal signs associated with it. Participants will learn about the roles of phagocytes, plasma proteins, and the stages of the inflammatory response. Test your knowledge on how these mechanisms work together to protect the body from injury and infection.