Nokea
Which of the following statements is incorrect about allergic reactions?
- A. They always require a sensitization step during which specific IgE are secreted
- B. Allergens causing hay fever are usually inhaled
- C. Food allergy can cause hives
- D. The current guidelines for preventing peanut allergy in infants is complete avoidance of peanuts and peanut-related products until at least six months of age
Correct Answer: D
Rationale: The correct answer is D because current guidelines actually recommend early introduction of peanuts to prevent peanut allergies, not complete avoidance. This is based on research showing early introduction can reduce the risk of developing peanut allergies. Choice A is correct as sensitization is a key step in allergic reactions. Choice B is correct as inhaled allergens can cause hay fever. Choice C is correct as food allergies can indeed manifest as hives.
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What type of receptor is found on B cells for antigen recognition?
- A. T cell receptor (TCR)
- B. B cell receptor (BCR)
- C. Fc receptor
- D. Complement receptor
Correct Answer: B
Rationale: The correct answer is B because B cells express B cell receptors (BCR) on their surface for recognizing antigens. BCRs consist of immunoglobulin molecules that bind specifically to antigens. T cell receptors (A) are found on T cells, not B cells. Fc receptors (C) bind to the Fc region of antibodies, while complement receptors (D) recognize complement proteins, not antigens. Therefore, the BCR is the specific receptor on B cells for antigen recognition.
What is the medical term for the breakdown of red blood cells?
- A. Leukocytosis
- B. Thrombocytosis
- C. Hemolysis
- D. Anemia
Correct Answer: C
Rationale: The correct answer is C: Hemolysis. Hemolysis is the medical term for the breakdown of red blood cells. This process releases hemoglobin and other components into the bloodstream. Leukocytosis (A) is an increase in white blood cells, thrombocytosis (B) is an increase in platelets, and anemia (D) is a decrease in red blood cells or hemoglobin levels. In this context, hemolysis specifically refers to the breakdown of red blood cells, making it the correct answer.
Which of the following is not required for full activation of a naïve lymphocyte?
- A. Migration into an inflammatory site
- B. Costimulatory signalling
- C. Cytokines
- D. Recognition of specific antigen
Correct Answer: A
Rationale: The correct answer is A. Naïve lymphocytes require activation through recognition of specific antigen, costimulatory signaling, and cytokines. Migration into an inflammatory site is not a requirement for full activation. Naïve lymphocytes can be activated in secondary lymphoid organs where antigen presentation occurs. Migration to inflammatory sites occurs after activation to fight infections.
How many Toll-like receptors (TLRs) are found in humans?
- A. 5
- B. 8
- C. 10
- D. 12
Correct Answer: C
Rationale: The correct answer is C: 10. Toll-like receptors (TLRs) are a family of proteins involved in the innate immune response. In humans, there are 10 known TLRs that recognize different pathogen-associated molecular patterns. Each TLR is specific to different types of pathogens, allowing for a diverse recognition and response system. Therefore, the correct answer is 10. Choices A, B, and D are incorrect because they do not match the known number of TLRs in humans, which is 10.
Which symptom is NOT typically associated with anaphylaxis?
- A. Sudden drop in blood pressure
- B. Massive edema
- C. Severe bronchoconstriction
- D. T cell apoptosis
Correct Answer: D
Rationale: The correct answer is D: T cell apoptosis. Anaphylaxis is a severe allergic reaction that involves a rapid immune response. T cell apoptosis is not a typical symptom of anaphylaxis.
Rationale:
1. A: Sudden drop in blood pressure is associated with anaphylaxis due to systemic vasodilation.
2. B: Massive edema is common in anaphylaxis due to increased vascular permeability.
3. C: Severe bronchoconstriction is a hallmark of anaphylaxis, leading to respiratory distress.
4. D: T cell apoptosis is not a characteristic feature of anaphylaxis. T cells play a role in adaptive immunity, not the immediate hypersensitivity reaction seen in anaphylaxis.
Summary:
T cell apoptosis is not typically associated with anaphylaxis, unlike the other symptoms listed which are common manifestations of this severe allergic reaction.