Chapter 18 Flashcards
Disorders of the immune system may be result of
Over-reacting or under-reacting
An over-reaction of an immune response against a foreign antigen
Hypersensitivites
4 types of hypersensitivity
Type I
Type II
Type III
Type IV
Type I
Immediate
Type II
Cytotoxic
Type III
Immune complex-mediated
Type IV
Delayed or cell mediated
Type I (Immediated) Hypersensitivity
Localized or systemic
Rwaction that reults from the relaease of inflammatory molecules in response to an antigen
Type I (Immediated) Hypersensitivity
Develops within seconds or minutes following exposure to an antigen
Type I (Immediated) Hypersensitivity
Commonly called an allergy
Type I (Immediated) Hypersensitivity
The antigens that stimulate allergies are called allergen
Type I (Immediated) Hypersensitivity
The antigens that stimulate allergies are called
Allergen
Mechanisms of a type I hypersensitivity reaction
1) Antigen-presenting cell, engulfs allergen, and exposes the atigen to Th2 (type II helper T-cell)
2) Th2 release IL-4 —> B-cell
3) B-cell –> Plasma cell
4) Plasma Cell secretes IgE
5) The Fc portion of IgE bind to mast cells, Basophils and Eosinophills, sensitizing them to subsequent
Subsequent exposure to same alergen binds to IgE on the surface of Mast cells Basophils and Eosinophils These cells release inflammatory chemicals from granules called
Degranulation
During degranulation what is released
Histamin Kinins Protease Leukotrienes Prostaglandins
Occurs after cels sensitized
Dengranulation
Derived from stem cells in bone marrow, distributed throughout body (______)
Mast cells
Not Wbcs
Least numerous wbc, (granular wbc)
Basophils
dilates blood vessels, tears, mucous, contractions of smooth muscle (swollen)
Histimines
Inflammation
Kinins
Degrades proteins, activates complement
Proteases
Inflammation, vascular permeability
Leukotrienes
Contract and relax smooth muscle
Prostaglandins
Function primarily for parasitic worms release leukotrines which increase vascular permeability and muscular contraction
Eosinophils
Clinical signs of localized allergic reactions
Localized
Site of reaction depends on portal of entry
Localized
Small inhale allergens may reach lungs and cause _________
Asthma
COntrisction of bronchi
Asthma
Some foods contain allergens
May cause diarrhea and other gastorintestinal signs and symptoms
Local dermatitis may produce ________
Urticaris
Urticaris
raised red areas of skin, itchy b/c histamine affecets nerve endings in area
Common allergens
Pollen
Dust mites
Spore
Clinical signs of systemic allergic reactions
Systemic
Many mast cells may degranulate at once
releasing large amounts of histamine and inflammatory mediators
The release of inflammatory mediators may
exceed the body’s ability to adjust
The release of inflammatory mediators may exceed the body’s ability to adjust may result in
acute anaphylaxis or andphylactic shock
Clinincal signs of acute anaphylaxs or anaphylactic shock
suffoction
Diagnosis of type I hypersensitivity based on
detection of high levels of IgE against specific allergen
Diagnosis of type I sample of blood is taken and mixed with
antigen to determine the IgE quantity in blood
What type of blood sample is taken in type I hypersensitivity
Immunocap specifies IgE blood test
Type I
Alternatively, diagnoses can involve using skin test:
Inject dilute allergen into skin of forearm observe for any inflammation
Prevention of type I hypersensitivity
Identification and avoidance of allergens
Food allergens identified using an
elimination diet
Immunotherapy __________ can help prevent allergic reactions
“Allergy shots”
“allergy shots” administration of a series of injections of
dilute allergen
Treatment of type I hypersensitivity
administer drugs that counteract infammatory mediators
.
Neutralize histamine
Treat asthma with Corticosteroid (counteracts a inflammatory mediator) and a _____________.
.
________ neutralizes many mechanisms of anaphlaxis
.
