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Questions and Answers
What is the term for substances that induce fever?
What is the term for substances that induce fever?
Which cytokines are endogenous pyrogens?
Which cytokines are endogenous pyrogens?
Which prostaglandin plays a significant role in fever induction?
Which prostaglandin plays a significant role in fever induction?
How does fever induction influence body temperature regulation?
How does fever induction influence body temperature regulation?
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What type of acute-phase proteins are primarily synthesized in the liver?
What type of acute-phase proteins are primarily synthesized in the liver?
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Which of the following proteins is an example of an acute-phase protein?
Which of the following proteins is an example of an acute-phase protein?
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What is the role of cyclooxygenases in fever induction?
What is the role of cyclooxygenases in fever induction?
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How do pyrogens impact the body's steady-state temperature?
How do pyrogens impact the body's steady-state temperature?
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What are the two primary effects of fever on the body to increase heat generation?
What are the two primary effects of fever on the body to increase heat generation?
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Which two types of pyrogens are mentioned in the text?
Which two types of pyrogens are mentioned in the text?
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Study Notes
Systemic Reactions
- Fever is a protective host response, characterized by an elevation of body temperature, often associated with infection.
- Pyrogens, such as bacterial products (exogenous pyrogens) and cytokines (endogenous pyrogens), induce fever.
- IL-1 and TNF act by stimulating the release of endogenous pyrogens, which upregulate cyclooxygenases to synthesize prostaglandins.
- Prostaglandins, primarily PGE2, synthesized by vascular and perivascular cells of the hypothalamus, stimulate the production of neurotransmitters to reset the body's steady-state temperature.
Acute-Phase Proteins
- Elevated levels of acute-phase proteins, such as C-reactive protein (CRP), fibrinogen, and serum amyloid A (SAA) protein, are synthesized in the liver.
Inflammation
- Inflammation is a protective response to tissue injury or infection, characterized by the 5 'R's: redness, swelling, heat, pain, and loss of function.
- Causes of inflammation include physical, chemical, biological, and immune-mediated injuries.
Acute Inflammation
- Vasodilation and increased blood flow lead to increased vascular permeability and stasis.
- Recruitment of leukocytes to sites of inflammation involves margination, rolling, adhesion, migration, and chemotaxis.
- Removal of offending agents via phagocytosis involves recognition and attachment, engulfment, and intracellular destruction.
- Endothelial and neuronal NOS are constitutively expressed at low levels, while iNOS is involved in microbial killing and induced when macrophages +/- neutrophils are activated.
Leukocyte-Mediated Tissue Injury
- Leukocyte-mediated tissue injury occurs via the release of lysosomal enzymes, such as MPO, bactericidal proteins, acid hydrolases, and neutral proteases.
- Macrophages also contain acid hydrolases, collagenase, and elastase, which degrade bacteria, debris, extracellular matrix components, and complement proteins.
Morphologic Patterns of Acute Inflammation
- General morphologic features include vascular dilation and congestion, edema, and inflammatory cellular infiltrate within the extravascular tissue.
- Specific morphologic patterns include serous inflammation, fibrinous inflammation, suppurative (purulent) inflammation, and ulcers.
Outcomes of Acute Inflammation
- Three possible outcomes of acute inflammation: complete resolution, scarring/fibrosis, and chronic inflammation.
- Complete resolution is the ideal outcome, where injury is limited, and removal of cellular debris and microbes by macrophages occurs, allowing for regeneration of damaged cells.
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Description
Test your knowledge on the causes of inflammation, the cardinal signs of acute inflammation, inflammatory cells, chemical mediators, morphologic patterns, and the effects of inflammation. Learn about both damaging and beneficial effects of inflammation, and distinguish between local and systemic manifestations.
