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Questions and Answers
What is a primary purpose of inflammation?
What is a primary purpose of inflammation?
Chronic inflammation occurs rapidly within minutes to hours.
Chronic inflammation occurs rapidly within minutes to hours.
False
Name the main components of inflammation.
Name the main components of inflammation.
Vascular reaction and Cellular response
The features of acute inflammation include _____, redness, swelling, pain, and loss of function.
The features of acute inflammation include _____, redness, swelling, pain, and loss of function.
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Which type of cells primarily infiltrate during acute inflammation?
Which type of cells primarily infiltrate during acute inflammation?
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What process is initiated by the activation of factor XII?
What process is initiated by the activation of factor XII?
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Increased vascular permeability leads to the leakage of plasma proteins during inflammatory response.
Increased vascular permeability leads to the leakage of plasma proteins during inflammatory response.
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Match the type of inflammation with its characteristics:
Match the type of inflammation with its characteristics:
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Name one beneficial effect of acute inflammation.
Name one beneficial effect of acute inflammation.
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What mediators are known to induce vasodilation during acute inflammation?
What mediators are known to induce vasodilation during acute inflammation?
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The exudate of protein-rich extravascular fluid leads to tissue __________.
The exudate of protein-rich extravascular fluid leads to tissue __________.
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In acute inflammation, neutrophils are the first type of leukocytes to adhere to the endothelium.
In acute inflammation, neutrophils are the first type of leukocytes to adhere to the endothelium.
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Match the type of inflammation with its duration.
Match the type of inflammation with its duration.
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Which of the following outcomes may occur after acute inflammation?
Which of the following outcomes may occur after acute inflammation?
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What is the primary role of leukocyte recruitment during inflammation?
What is the primary role of leukocyte recruitment during inflammation?
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Which of the following is NOT a consequence of inflammation?
Which of the following is NOT a consequence of inflammation?
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What primarily causes chronic inflammation?
What primarily causes chronic inflammation?
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Neutrophils are the last leukocytes to arrive at sites of inflammation.
Neutrophils are the last leukocytes to arrive at sites of inflammation.
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What cytokines are primarily responsible for promoting leukocyte migration?
What cytokines are primarily responsible for promoting leukocyte migration?
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The process of leukocyte recruitment involves attachments mediated by ________ and ________ on the endothelium.
The process of leukocyte recruitment involves attachments mediated by ________ and ________ on the endothelium.
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Match the major mediators of inflammation with their effects:
Match the major mediators of inflammation with their effects:
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Kinins are produced by the degradation of complement proteins.
Kinins are produced by the degradation of complement proteins.
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Lysosomal enzymes play no role in tissue injury during inflammation.
Lysosomal enzymes play no role in tissue injury during inflammation.
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What is the mechanism by which leukocytes eliminate microbes?
What is the mechanism by which leukocytes eliminate microbes?
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Which type of inflammation is characterized by an aggregation of activated macrophages?
Which type of inflammation is characterized by an aggregation of activated macrophages?
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Match the following types of inflammation with their descriptions:
Match the following types of inflammation with their descriptions:
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What are the main cellular components involved in chronic inflammation?
What are the main cellular components involved in chronic inflammation?
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Cytokines produced by ___ and ___ are important mediators of chronic inflammation.
Cytokines produced by ___ and ___ are important mediators of chronic inflammation.
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Which of the following is NOT a systemic effect of inflammation?
Which of the following is NOT a systemic effect of inflammation?
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Match the type of inflammation with its causes:
Match the type of inflammation with its causes:
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The cell cycle is regulated by both stimulators and ___ to prevent abnormal cell replication.
The cell cycle is regulated by both stimulators and ___ to prevent abnormal cell replication.
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Chronic inflammation is solely caused by acute infections.
Chronic inflammation is solely caused by acute infections.
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What type of inflammation is characterized by the presence of purulent exudates?
What type of inflammation is characterized by the presence of purulent exudates?
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Adult stem cells are capable of generating multiple cell lineages.
Adult stem cells are capable of generating multiple cell lineages.
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What is the role of the extracellular matrix (ECM) in tissue repair?
What is the role of the extracellular matrix (ECM) in tissue repair?
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The process of introducing genes characteristic of embryonic stem cells into mature cells results in __________ stem cells.
The process of introducing genes characteristic of embryonic stem cells into mature cells results in __________ stem cells.
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Which of the following components make up the extracellular matrix?
Which of the following components make up the extracellular matrix?
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Name the cytokines that stimulate the production of acute-phase proteins.
Name the cytokines that stimulate the production of acute-phase proteins.
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Scar formation occurs when the extracellular matrix is damaged.
Scar formation occurs when the extracellular matrix is damaged.
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Which type of inflammation occurs when there is an erosion of the epithelial surface due to necrosis?
Which type of inflammation occurs when there is an erosion of the epithelial surface due to necrosis?
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Study Notes
Inflammation
- Inflammation is a complex, protective response to foreign invaders and necrotic tissue, but it can also cause tissue damage.
- The main components of inflammation are the vascular reaction and the cellular response, both activated by mediators derived from plasma proteins and various cells.
- Inflammation involves five steps: recognition of the injurious agent, recruitment of leukocytes, removal of the agent, regulation (control) of the response, and resolution (repair).
Acute Inflammation
- Occurs over a short duration (minutes to days).
- Characterized by:
- Increased blood flow (hyperemia) due to vasodilation.
- Leakage of plasma proteins (exudation) due to microvascular structural changes.
- Emigration of leukocytes (neutrophils) towards the site of injury.
- Signs of acute inflammation include:
- Heat (calor)
- Redness (rubor)
- Swelling (tumor)
- Pain (dolor)
- Loss of function (functio laesa)
Reactions of Acute Inflammation
- Vasodilation is induced by mediators like histamine, resulting in erythema and blood flow stasis.
- Increased vascular permeability is caused by histamine, kinins, and other mediators, leading to fluid leak and edema.
Leukocyte Recruitment to Sites of Inflammation
- Leukocytes are recruited from the blood to the site of injury.
- Recruitment involves multiple steps:
- Loose attachment and rolling on endothelium (mediated by selectins).
- Firm attachment to endothelium (mediated by integrins).
- Migration through interendothelial spaces.
- Cytokines promote expression of selectins and integrin ligands on endothelium (TNF, IL-1), increase integrin avidity (chemokines), and promote directional migration (chemokines).
- Neutrophils dominate early inflammation, later replaced by macrophages.
Leukocyte Effector Mechanisms
- Leukocytes eliminate microbes and dead cells through phagocytosis and destruction in phagolysosomes.
- Destruction involves free radicals (ROS, NO) and lysosomal enzymes generated by activated leukocytes.
- Released enzymes and ROS can damage normal tissues.
Major Cell-Derived Mediators of Inflammation
- Vasoactive amines (histamine, serotonin): cause vasodilation and increased vascular permeability.
- Arachidonic acid metabolites (prostaglandins, leukotrienes): involved in vascular reactions, leukocyte chemotaxis, and other inflammatory responses; antagonized by lipoxins.
- Cytokines (TNF, IL-1, IL-6, chemokines): mediate multiple effects, mainly in leukocyte recruitment and migration; produced by many cell types.
- ROS: roles in microbial killing and tissue injury.
- NO: effects include vasodilation and microbial killing.
- Lysosomal enzymes: roles in microbial killing and tissue injury.
Plasma Protein–Derived Mediators of Inflammation
- Complement proteins: activation leads to multiple breakdown products involved in leukocyte chemotaxis, opsonization, phagocytosis, and cell killing.
- Coagulation proteins: activated factor XII triggers clotting, kinin, and complement cascades, and activates the fibrinolytic system.
- Kinins: produced by proteolytic cleavage, mediate vascular reaction and pain.
Sequence of Events in Acute Inflammation
- Arteriolar and capillary dilation increase blood flow (erythema and warmth).
- Increased vascular permeability leads to protein-rich extravascular fluid (tissue edema).
- Leukocytes adhere to endothelium via adhesion molecules and migrate to the site of injury under chemotactic influence.
- Phagocytosis, killing, and degradation of the offending agent follow.
Outcomes of Acute Inflammation
- Resolution: removal of exudate with tissue restoration to normality.
- Fibrosis: occurs when inflammation is in tissues that don't regenerate, after substantial tissue destruction, or with extensive fibrinous exudates.
- Abscess formation: focal collection of pus due to deep seeding of microbes or secondary infection of necrotic areas.
- Progression to chronic inflammation.
Chronic Inflammation
- Lasts for a longer duration (days to years).
- Characterized by:
- Infiltration by mononuclear cells (monocytes, lymphocytes, macrophages).
- Tissue destruction.
- Tissue repair (vascular proliferation and fibrosis).
Causes of Chronic Inflammation
- Persistent infections (tuberculosis, syphilis).
- Prolonged exposure to toxic agents.
- Autoimmune disorders.
Features of Chronic Inflammation
- Prolonged host response to a persistent stimulus.
- Caused by microbes resistant to elimination, immune responses against self or environmental antigens, and some toxic substances.
- Characterized by persistent inflammation, tissue injury, attempted repair by scarring, and immune response.
- Cellular infiltrate consisting of activated macrophages, lymphocytes, and plasma cells, often with prominent fibrosis.
- Mediated by cytokines produced by macrophages and lymphocytes, with a tendency to an amplified and prolonged inflammatory response.
Cells in Chronic Inflammation
- Macrophages: derived from monocytes, increasing in size, lysosome contents, and metabolic activity.
- Lymphocytes: various types are present, including T lymphocytes and B lymphocytes.
- Plasma cells: produce antibodies.
- Eosinophils: involved in parasitic infections and allergic reactions.
Granulomatous Inflammation
- Aggregation of activated macrophages with an epithelioid appearance.
- Can be caused by:
- Bacterial infections (tuberculosis, leprosy, syphilis).
- Parasitic infections (bilharziasis).
- Fungal infections (histoplasmosis).
- Inorganic metals (silica, berylliosis).
- Foreign bodies.
- Unknown causes (sarcoidosis).
Systemic Effects of Inflammation
- Fever: cytokines (TNF, IL-1) stimulate prostaglandin production in the hypothalamus.
- Production of acute-phase proteins: C-reactive protein stimulated by cytokines (IL-6) acting on liver cells.
- Leukocytosis: cytokines (CSFs) stimulate leukocyte production from bone marrow precursors.
- Septic shock: in severe infections, high levels of TNF cause a fall in blood pressure, disseminated intravascular coagulation, and metabolic abnormalities.
Cell Proliferation, the Cell Cycle, and Stem Cells
- Tissue regeneration is driven by proliferation of uninjured cells and replacement from stem cells.
- Cell proliferation occurs when quiescent cells enter the cell cycle, which is tightly regulated by stimulators and inhibitors.
- Tissues are divided into labile, stable, and permanent, based on their proliferative capacity.
- Labile tissues contain mature cells capable of dividing and stem cells that differentiate to replenish lost cells.
- Embryonic stem cells (ES cells) are pluripotent, while adult tissues contain adult stem cells capable of generating multiple cell lineages.
- Induced pluripotent stem cells (iPS cells) are derived by introducing genes characteristic of ES cells into mature cells.
Extracellular Matrix and Tissue Repair
- The ECM consists of interstitial matrix between cells (collagens and glycoproteins) and basement membranes (nonfibrillar collagen and laminin).
- The ECM provides mechanical support, acts as a substrate for cell growth, and regulates cell proliferation and differentiation.
- An intact ECM is essential for tissue regeneration, and its damage can lead to repair by scar formation.
Morphologic Patterns of Acute and Chronic Inflammation
- Serous Inflammation: watery, protein-poor fluid effusions derived from serum or mesothelial cells lining cavities.
- Fibrinous Inflammation: occurs in severe injuries, appearing as a meshwork of threads or an amorphous coagulum; exudate can be removed by macrophages or fibrinolysis or replaced by fibrosis.
- Suppurative (Purulent) Inflammation: characterized by large amounts of purulent exudate (pus) consisting of neutrophils, necrotic cells, and fluid; caused by pyogenic bacteria.
- Ulceration: erosion of an epithelial surface by necrosis with associated inflammation; can be caused by toxic, traumatic, or vascular factors.
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Description
This quiz explores the concept of inflammation, focusing on its protective role and potential tissue damage. You will learn about the stages of acute inflammation, the physiological changes involved, and the signs associated with it. Test your knowledge of the vascular and cellular responses to injury.
