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Questions and Answers
What is the primary characteristic of hypersensitivity reactions?
What is the primary characteristic of hypersensitivity reactions?
In which situation does autoimmunity occur?
In which situation does autoimmunity occur?
What can be a consequence of hypersensitivity reactions?
What can be a consequence of hypersensitivity reactions?
Which statement best describes the nature of autoimmune diseases?
Which statement best describes the nature of autoimmune diseases?
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Which of the following is an example of a hypersensitivity reaction?
Which of the following is an example of a hypersensitivity reaction?
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What initiates the sensitization phase in Type 1 hypersensitivity reactions?
What initiates the sensitization phase in Type 1 hypersensitivity reactions?
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What is the main consequence of subsequent exposures to an allergen in Type 1 hypersensitivity?
What is the main consequence of subsequent exposures to an allergen in Type 1 hypersensitivity?
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Which symptom is NOT commonly caused by the release of histamine in Type 1 hypersensitivity reactions?
Which symptom is NOT commonly caused by the release of histamine in Type 1 hypersensitivity reactions?
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Anaphylaxis is characterized by which of the following?
Anaphylaxis is characterized by which of the following?
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What is a common treatment for Type 1 hypersensitivity reactions?
What is a common treatment for Type 1 hypersensitivity reactions?
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Which of the following is usually considered the first step in developing a Type 1 hypersensitivity reaction?
Which of the following is usually considered the first step in developing a Type 1 hypersensitivity reaction?
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In the context of mast cell mediators, what role does histamine play?
In the context of mast cell mediators, what role does histamine play?
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Which condition represents a localized reaction in Type 1 hypersensitivity?
Which condition represents a localized reaction in Type 1 hypersensitivity?
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What is a key feature of the provocative dose in Type 1 hypersensitivity?
What is a key feature of the provocative dose in Type 1 hypersensitivity?
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Which of the following is NOT an effect of antihistamines in treating Type 1 hypersensitivity reactions?
Which of the following is NOT an effect of antihistamines in treating Type 1 hypersensitivity reactions?
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Match the types of hypersensitivity reactions with their primary characteristics:
Match the types of hypersensitivity reactions with their primary characteristics:
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Match the symptoms of Type 1 hypersensitivity reactions with their descriptions:
Match the symptoms of Type 1 hypersensitivity reactions with their descriptions:
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Match the phases of Type 1 hypersensitivity with their descriptions:
Match the phases of Type 1 hypersensitivity with their descriptions:
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Match the components involved in Type 1 hypersensitivity with their roles:
Match the components involved in Type 1 hypersensitivity with their roles:
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Match the allergic reactions with their common triggers:
Match the allergic reactions with their common triggers:
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Match the terms with their definitions in the context of Type 1 hypersensitivity:
Match the terms with their definitions in the context of Type 1 hypersensitivity:
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Match the allergic responses with their types:
Match the allergic responses with their types:
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Match the types of immune responses with their examples:
Match the types of immune responses with their examples:
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Match each term with the correct associated effect:
Match each term with the correct associated effect:
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Match the localized Type 1 reactions with their descriptions:
Match the localized Type 1 reactions with their descriptions:
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Match the systemic Type 1 reaction with its characteristic:
Match the systemic Type 1 reaction with its characteristic:
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Match the treatment methods for Type 1 hypersensitivity with their effects:
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Match the symptoms of anaphylaxis with their corresponding effects:
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Match the examples of allergens with their type of reaction:
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Match the localized allergic reactions with their triggers:
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Match the treatment options with their mechanisms:
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Match the symptoms of localized Type 1 reactions with their conditions:
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Match the types of hypersensitivity reactions with their categories:
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Match the common symptoms of food allergies with their expressions:
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Which antibodies are primarily involved in Type 2 hypersensitivity reactions?
Which antibodies are primarily involved in Type 2 hypersensitivity reactions?
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What is a consequence of Type 2 hypersensitivity reactions?
What is a consequence of Type 2 hypersensitivity reactions?
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Which condition is associated with hemolytic disease of the newborn due to Type 2 hypersensitivity?
Which condition is associated with hemolytic disease of the newborn due to Type 2 hypersensitivity?
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Type 2 hypersensitivity reactions are primarily directed at which of the following?
Type 2 hypersensitivity reactions are primarily directed at which of the following?
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Which of the following best describes the immune response in Type 2 hypersensitivity?
Which of the following best describes the immune response in Type 2 hypersensitivity?
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Which blood type is considered the universal donor and why?
Which blood type is considered the universal donor and why?
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What happens during a transfusion reaction when incompatible blood types are mixed?
What happens during a transfusion reaction when incompatible blood types are mixed?
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Which statement is true regarding the Rh factor?
Which statement is true regarding the Rh factor?
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What is the primary consequence of mixing Type A blood with Type B blood during transfusion?
What is the primary consequence of mixing Type A blood with Type B blood during transfusion?
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Which blood type contains both anti-A and anti-B antibodies?
Which blood type contains both anti-A and anti-B antibodies?
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What is the role of RhoGAM in pregnancy?
What is the role of RhoGAM in pregnancy?
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Which feature correctly describes Type AB blood?
Which feature correctly describes Type AB blood?
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What could be a serious consequence of a transfusion reaction?
What could be a serious consequence of a transfusion reaction?
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How do antibodies in blood function during a transfusion reaction?
How do antibodies in blood function during a transfusion reaction?
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What characterizes Rh negative individuals?
What characterizes Rh negative individuals?
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Match the blood types with their corresponding antigens:
Match the blood types with their corresponding antigens:
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Match the blood types with their corresponding antibodies:
Match the blood types with their corresponding antibodies:
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Match the blood types with their designated roles in transfusions:
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Match the transfusion reaction effects with their descriptions:
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Match the Rh factor types with their characteristics:
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Match the scenarios with their outcomes regarding the Rh factor:
Match the scenarios with their outcomes regarding the Rh factor:
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Match the blood type with the corresponding risk of transfusion reaction:
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Match the types of immune responses with their effects on blood types:
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Match the possible consequences of mismatched blood transfusions:
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Study Notes
Hypersensitivity Reactions
- Hypersensitivity reactions are exaggerated immune responses that can damage self tissues.
- These reactions occur when the immune system misdirects its response.
Autoimmunity
- Autoimmunity occurs when the immune system mistakenly attacks the body's own tissues.
- Each autoimmune disease targets different specific tissues.
Hypersensitivity Reactions
- Exaggerated immune responses that damage self-tissues
- Classified into four types based on the mechanism of reaction
- Type 1 reactions are commonly known as allergies
- Type 1 reactions are mediated by IgE antibodies
Type 1 Hypersensitivity Reactions
- Occur with at least two exposures to an allergen
- Sensitizing dose: First exposure, IgE is produced and binds to mast cells
- Provocative dose: Subsequent exposures, triggers the release of chemical mediators from mast cells causing symptoms
- Chemical mediators include histamine
Mast Cell Mediators
- Histamine and other chemical mediators cause various symptoms:
- Vasodilation: Leading to skin rashes
- Bronchial constriction: Leading to wheezing
- Stimulation of glands: Leading to tear and mucus production
Examples of Type 1 Reactions
-
Localized Reactions:
- Hay fever (allergic rhinitis): Inhaled allergens like dust, mold, or pollen
- Asthma: Inhaled or ingested allergens causing severe bronchial constriction
- Eczema: Inhaled or ingested allergens triggering inflammatory skin reactions
- Food or drug allergies: Ingested or injected allergens causing vomiting, diarrhea, rash, or other skin complications
-
Systemic Reaction:
-
Anaphylaxis: Systemic reaction to an allergen, causing widespread vasodilation and potentially fatal shock
- Can be triggered by insect stings, antibiotics, or serum injections
-
Anaphylaxis: Systemic reaction to an allergen, causing widespread vasodilation and potentially fatal shock
Treatment of Type 1 Hypersensitivity Reactions
- Avoidance of allergen
- Corticosteroids: Inhibit B and T cell activity, reducing IgE production
- Antihistamines: Block histamine receptors, preventing the action of histamine released by mast cells
Hypersensitivity Reactions
- An exaggerated immune response that results in tissue damage
- Four types:
- Type 1: Involve IgE antibodies and mast cells, considered allergies.
- Type 2: Involve cytotoxic antibodies.
- Type 3: Involve immune complexes.
- Type 4: T-cell mediated.
Type 1: IgE Antibodies and Mast Cells
- Requires at least two exposures to the allergen
-
First exposure (sensitizing dose): Triggers the production of IgE antibodies
- Allergen binds to B cell receptor
- B cell presents allergen to T helper cells
- T helper cells activate the B cell to release IL-4
- T helper 2 cells release IL-4
- B cells differentiate into plasma cells that produce IgE antibodies
- IgE antibodies bind to mast cells
-
Subsequent exposures (provocative dose): Triggers mast cell degranulation
- Allergen binds to IgE on mast cells
- Activates mast cells to release chemical mediators (histamine)
-
First exposure (sensitizing dose): Triggers the production of IgE antibodies
Type 1 Symptoms
-
Histamine release causes:
- Vasodilation: Redness, itching, rashes
- Bronchial constriction: Wheezing, difficulty breathing, coughing
- Nerve stimulation: Headaches
- Gland stimulation: Increased tear and mucus production
Localized Type 1 Reactions
-
Examples:
- Hay fever (allergic rhinitis)
- Asthma
- Eczema
- Food allergies
- Drug allergies
Systemic Type 1 Reactions: Anaphylaxis
- Life-threatening, widespread response
- Can be triggered by insect stings, antibiotics, and serum injections
- Characterized by systemic vasodilation, bronchial constriction, and shock
Type 1 Treatment
- Avoidance: The easiest and most effective way to manage allergies
- Corticosteroids: Inhibit B cell and T cell activity
- Antihistamines: Block histamine receptors on target tissues
Type 2 Hypersensitivity Reactions
- Involve IgG and IgM antibodies.
- These are antibodies normally produced during humoral immune responses.
- These reactions are directed at foreign blood cells.
- This leads to transfusion reactions and Hemolytic Disease of the Newborn.
Blood Types
- Based on antigens present on red blood cells
- Type A: Contains A antigen, has anti-B antibodies
- Type B: Contains B antigen, has anti-A antibodies
- Type AB: Contains both A and B antigens, has neither anti-A nor anti-B antibodies
- Type O: Contains neither A nor B antigens, has anti-A and anti-B antibodies
- Type O blood is the universal donor due to the lack of A and B antigens
Transfusion Reactions
- Occur when incompatible blood types are mixed, causing a hypersensitivity reaction, leading to:
- Agglutination: clumping of red blood cells
- Hemolysis: destruction of red blood cells
- Complement Activation: cell lysis and inflammation
- Systemic Shock: due to widespread inflammation and organ damage
- Kidney Failure: from the filtration of red blood cell debris by the kidneys
- Death: can occur quickly due to these complications
Rh Factor
- Another antigen found on some red blood cells
- Rh-positive blood is present in ~85% of humans, contains Rh antigen
- Rh-negative blood is present in ~15% of humans, lacks Rh antigen
- Rh-negative individuals do not have antibodies against Rh unless previously exposed
-
Hemolytic Disease of the Newborn: occurs when an Rh-negative mother carries an Rh-positive fetus:
- During pregnancy, the mother's immune system is not exposed to Rh-positive fetal blood cells
- At birth, there's a mixing of maternal and fetal blood, which leads to the mother developing antibodies against Rh-positive blood
- This can lead to destruction of red blood cells in future pregnancies, causing miscarriage, premature birth, or hemolytic disease of the newborn
- RhoGAM: injection of anti-Rh antibodies given to Rh-negative mothers during and after pregnancy to prevent the development of antibodies against Rh-positive fetal blood cells
Studying That Suits You
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Description
Test your knowledge on hypersensitivity reactions and autoimmunity. This quiz covers the mechanisms of these immune responses and their effects on the body. Understand how the immune system can misfire and lead to tissue damage.