30 Questions
What is the primary mediator of anaphylactic reactions?
Histamine
Which cells are primarily involved in the sensitization phase of anaphylaxis?
Basophils
What is the main effect of anaphylactic reactions on non-vascular smooth muscles?
Increased contraction
Which of the following is a local manifestation of anaphylaxis?
Urticaria (hives)
Why do injected antigens often trigger more severe anaphylactic reactions compared to other routes of exposure?
They activate mast cells directly
Which type of hypersensitivity reaction is characterized by immediate onset within 2-30 minutes?
Type I
What type of reaction usually involves antigens that are ingested or inhaled?
Immediate reaction
Which type of reaction involves antibodies against cellular or tissue antigens and generally activates complement?
Localized Anaphylaxis
What is the name for reactions mediated by IgG antibodies 6 to 8 hours after exposure to an antigen?
Serum sickness
Which of the following is an example of a Delayed Type reaction caused by T-cells mainly?
Allergic Contact Dermatitis
What does the term 'Anaphylaxis' mean based on its Greek roots?
Against/backward guard
Which of the following is NOT a characteristic of immediate reactions due to Ag-Ab complexes?
6 to 8 hours delay after exposure
Which of the following is NOT a common antibiotic used in dentistry?
Ibuprofen
What is the most likely route of exposure to cause sensitization to a drug?
Topical
Which of the following is a characteristic of a rapid-onset allergic reaction to a drug?
More aggressive management needed
What is a common skin manifestation of a drug allergy?
Erythema multiforme
Which of the following is a characteristic of the sensitization process for a drug allergy?
It requires years of constant exposure before symptoms appear
What is the most common group of skin manifestations associated with drug allergies?
Drug eruption
What percentage of Adverse Drug Reactions (ADRs) are dose-related?
85%
Which type of ADRs do not require a certain dose to elicit a response?
Allergies
Which drug is NOT listed as having a high allergenic potential?
Lidocaine
Which type of anesthetics was commonly used before and had a higher allergic potential?
Ester type anesthesia
What type of reaction occurs generally when the patient is first exposed to a particular drug or agent?
Idiosyncratic reactions
Which factor contributes to potentially severe, life-threatening allergic reactions in patients?
Previous exposure to an allergen
What is the leading cause of anaphylaxis?
Parenteral penicillin
Which of the following is NOT one of the four major clinical syndromes of anaphylaxis?
Fever
Which of the following symptoms indicates a later stage of anaphylaxis?
Pallor
What is the emergency drug used to treat anaphylaxis?
Epinephrine
Which of the following best describes an idiosyncrasy?
An individual's unique hypersensitivity
What is the most severe consequence of anaphylaxis mentioned in the text?
Cardiac arrest
Study Notes
Immediate Hypersensitivity Reactions
- Mediated by B Lymphocytes, Mast cells, and IgE
- Characterized by sensitization of mast cells and basophils, leading to:
- Capillary dilation and increased capillary permeability (blushing, erythema, edema)
- Release of chemical mediators (histamine, prostaglandins) causing pain, itch, and vasodilation
- Decreased venous return, decreased blood pressure, and decreased cardiac output
- Smooth muscle constriction (bronchospasm) and increased secretion from mucous glands (rhinitis)
Types of Hypersensitivity Reactions
-
Immediate (Type I) Hypersensitivity: IgE-mediated, anaphylactic reactions occurring within 2-30 minutes
- Examples: Generalized anaphylaxis, localized anaphylaxis (urticaria, bronchospasm, food allergy)
-
Cytotoxic (Type II) Hypersensitivity: IgG or IgM-mediated, antibody-dependent cytotoxicity
- Examples: Hemolytic anemia, transfusion reactions
-
Immune Complex (Type III) Hypersensitivity: IgG-mediated, immune complex reactions occurring 6-8 hours after exposure
- Examples: Serum sickness, acute viral hepatitis
-
Delayed (Type IV) Hypersensitivity: Cell-mediated, T-cell mediated reactions occurring 1-2 days after exposure
- Examples: Infectious granulomas (TB), allergic contact dermatitis, chronic hepatitis
Anaphylaxis
- A severe, life-threatening allergic reaction characterized by rapid onset of symptoms
- Can be caused by food, insect stings, drugs, or other substances
- Symptoms include:
- Skin: itching, hives, flushing, angioedema
- Respiratory: coughing, wheezing, dyspnea
- Cardiovascular: tachycardia, hypotension, cardiac arrhythmias
- Gastrointestinal: nausea, vomiting, diarrhea
- Neurological: anxiety, confusion, loss of consciousness
Clinical Manifestations of Allergic Reactions
- Cutaneous manifestations: urticaria, maculopapular rash, erythema, vesicles, ulcers
- Angioedema
- Serum sickness symptoms
- Fixed drug eruption
Anaphylactic Shock and Cardiac Arrest
- Severe, life-threatening complications of anaphylaxis
- Symptoms include:
- Pallor
- Lightheadedness
- Palpitation
- Tachycardia
- Hypotension
- Cardiac arrhythmias
- Cardiac arrest
Test your knowledge on hyperimmune responses and chemical mediators involved in allergic reactions. Explore the roles of B lymphocytes, mast cells, IgE, and the chemical mediators responsible for symptoms like capillary dilation, increased capillary permeability, pain, itch, bronchospasm, and mucous gland secretion.
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