02/23a Inflammation I Flashcards
What is inflammation?
Body’s response to injury, including infection
What are the functions of inflammation?
To destroy, dilute, or wall off the injurious agent
To initiate the repair process
Inflammation is fundamentally a protective response. In what specific examples is inflammation harmful?
Hypersensitivity reactions - insect bites, drugs, etc.
Chronic diseases such as arthritis and atherosclerosis
Disfiguring scars
Visceral adhesions
What are the two components of an inflammatory response?
Vascular reaction
Cellular reaction
How is inflammation initiated?
By chemical mediators that are derived from plasma proteins or from cells
What are the three types of inflammation?
Acute
Chronic
Granulomatous
What are the major characteristics of acute inflammation (cells, time, etc.)
Short duration
Mainly neutrophils
Causes edema
What are the major characteristics of chronic inflammation?
Longer duration
Mainly lymphocytes and macrophages
Causes fibrosis and angiogenesis
What are the major characteristics of granulomatous inflammation?
A type of chronic inflammation
Predominance of epithelioid cells (activated macrophages) and possible multinucleated giant cells
What are the three major components of acute inflammation?
1) Increase in blood flow
2) Edema resulting from vasodilation and protein leakage
3) Leukocyte migration from circulation to focus of injury
What can stimulate acute inflammation?
Infections Trauma Physical or chemical agents Foreign bodies Immune reactions
What are five mechanisms of increasing vascular permeability?
1) Formation of gaps between cells due to endothelial contraction - most common, fast and short-lived
2) Direct injury to the vessel - fast, may be long-lived
3) Leukocyte-dependent injury - release of factors that damage vessel walls, often happens in the lungs
4) Increased transcytosis (exocytosis of fluid)
5) New blood vessel formation - new vessels tend to be leaky, can be significant in the eye
What is extravasation?
Deliver of leukocytes from a vessel lumen to the interstitium
What is diapedesis?
Migration of a leukocyte across the endothelium
What is chemotaxis?
Migration of a leukocyte into the interstitial fluid
Describe the timeline of leukocyte emigration - which cells predominate at what time after injury?
6-24 hours after injury - neutrophils predominate
24-48 hours after injury - monocytes predominate
What are the four possible outcomes of acute inflammation?
1) Complete resolution of the infection/injury
2) Abscess formation
3) Fibrosis - occurs after substantial tissue destruction, in tissues that cannot regenerate, or after abundant fibrin exudation
4) Progression into chronic inflammation
In what cases might your body skip acute inflammation and progress directly to chronic inflammation?
Certain viral infections
What are four morphological patterns seen in acute inflammation?
Serous inflammation
Fibrinous inflammation
Suppurative inflammation
Ulcers
What is serous inflammation?
An outpouring of thin fluid (burn blisters)
What is fibrous inflammation?
Leakage of fibrin into body cavities that may lead to scar tissue (adhesions)
What is suppurative or purulent inflammation?
Formation of pus or purulent exudate, a mixture of neutrophils, debris, and edema fluid (abscess)
What is an ulcer?
A local defect on the surface of an organ or tissue produced by sloughing of inflammatory necrotic tissue
What are the systemic manifestations of acute inflammation?
Endocrine and metabolic Fever Autonomic Behavioral Leukocytosis or leukopenia
What is the purpose of a fever?
Improves efficiency of leukocyte killing
Impairs replication of many offending organisms
What are the endocrine and metabolic manifestations of acute inflammation?
Secretion of acute phase proteins by the liver
Increased production of glucocorticoids in response to stress
Decreased secretion of vasopressin, resulting in body fluid reduction
What are the autonomic manifestations of acute inflammation?
Redirection of blood flow from skin to deep vascular beds
Increased pulse and blood pressure
Decreased sweating to preserve fluid volume
What are some behavioral manifestations of acute inflammation?
Shivering Chills Anorexia Somnolence Malaise
What is leukocytosis? What infections cause it?
Increased leukocyte count
Bacterial infections can cause neutrophilia
Certain viral infections can cause lymphocytosis
Parasites, asthma, and hay fever can cause eosinophilia
What is leukopenia? What infections cause it?
Decreased leukocyte count
Can be caused by typhoid fever, some viruses, rickettsiae, and protozoa
What types of infections and injuries can cause chronic inflammation?
Persistent infections such as syphilis and certain viruses, fungi, and parasites
Exposure to toxic agents, which can be exogenous (silica dust) or endogenous (toxic plasma lipid components leading to atherosclerosis)
Autoimmunity, as in cases of rheumatoid arthritis and systemic lupus erythematosis
What are the histological features of chronic inflammation?
Infiltration with mononuclear cells (T cells, B cells, macrophages)
Tissue destruction
Healing by replacement of damaged tissue by fibrosis and angiogenesis
What are the functions of macrophages in chronic inflammation?
Secrete biologically active products to engulf microbes and kill them, stimulate inflammation, and repair tissue
What are the functions of lymphocytes in chronic inflammation?
Produce inflammatory mediators
Participate in cell-mediated immune reactions
Produce antibody (B cells)
What are the functions of eosinophils in chronic inflammation?
Combat parasitic infections with toxic proteins contained in their granules
Active in immune reactions mediated by IgE (such as allergies)
What is the function of mast cells in chronic inflammation?
Release histamine and cytokines
What is a granuloma?
A focal area of granulomatous inflammation
What are the two types of granulomas?
Foreign body granuloma - forms when a foreign material is too large to be engulfed by a single macrophage
Immune granulmoa - forms when insoluble or poorly soluble particles elicit a cell-mediated immune response
