Nokea
Which of the following sentences is NOT true about type I hypersensitivity reactions?
- A. Symptoms manifest in allergic individuals only after a second encounter with an allergen
- B. Food allergies can result in systemic anaphylaxis
- C. TH2 lymphocytes are involved in their development
- D. They can be classified as genetic disorders because they are caused by a single gene defect
Correct Answer: D
Rationale: Step 1: Type I hypersensitivity reactions are immediate allergic reactions that occur upon initial exposure to an allergen, not just after a second encounter.
Step 2: Food allergies can lead to systemic anaphylaxis due to the rapid release of mediators like histamine.
Step 3: TH2 lymphocytes play a crucial role in the development of type I hypersensitivity reactions by promoting IgE production.
Step 4: Type I hypersensitivity reactions are not generally classified as genetic disorders since they result from an immune response to allergens, not a single gene defect.
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Which antibody is transported across the placenta?
- A. IgA
- B. IgM
- C. IgG
- D. IgE
Correct Answer: C
Rationale: The correct answer is C: IgG. IgG is the only antibody that can be transported across the placenta from the mother to the fetus, providing passive immunity to the newborn. This transfer of IgG occurs through the neonatal Fc receptor (FcRn) present in the placenta. IgA is primarily found in mucosal secretions, IgM is too large to cross the placenta, and IgE is involved in allergic reactions and parasitic infections, not placental transfer. Therefore, IgG is the only antibody capable of crossing the placenta and providing immune protection to the fetus.
A patient has come to the ambulatory care clinic with a sprain. The nurse correctly differentiates a grade 2 sprain from a grade 3 sprain with the assessment of which finding?
- A. Pain
- B. Swelling
- C. Bleeding into the joint
- D. Minor loss of function
Correct Answer: D
Rationale: The correct answer is D: Minor loss of function. A grade 2 sprain involves partial tearing of the ligament, leading to moderate pain, swelling, and a significant loss of function. In contrast, a grade 3 sprain involves complete tearing of the ligament, resulting in severe pain, significant swelling, and major loss of function. By assessing for minor loss of function, the nurse can differentiate between the two grades of sprains. Choices A, B, and C are incorrect because they do not specifically differentiate between a grade 2 and grade 3 sprain based on the level of functional impairment.
Which of the following is NOT commonly associated with granulomatous hypersensitivity?
- A. Crohn's disease
- B. Sarcoidosis
- C. Systemic lupus erythematosus (SLE)
- D. Tuberculosis
Correct Answer: C
Rationale: Granulomatous hypersensitivity is characterized by the formation of granulomas in response to persistent antigen exposure. Systemic lupus erythematosus (SLE) is an autoimmune disease involving immune complex deposition and inflammation, not granuloma formation. Crohn's disease, sarcoidosis, and tuberculosis are commonly associated with granulomatous hypersensitivity due to their chronic inflammatory nature and granuloma formation in affected tissues. SLE does not typically present with granulomas, making it the correct answer.
What is the role of a nurse during the scratch test to detect allergies?
- A. Applying the liquid test antigen
- B. Measuring the length and width of the raised wheal
- C. Determining the type of allergy
- D. Documenting the findings
Correct Answer: B
Rationale: The nurse measures the size of the wheal and flare reaction to determine the severity of the allergic response.
What is the significance of isotype switching in B cells?
- A. It enables the production of IgM only
- B. It enhances antibody affinity for antigens
- C. It changes the constant region to produce different antibody isotypes
- D. It eliminates antigen-specific B cells
Correct Answer: C
Rationale: Isotype switching in B cells involves changing the constant region to produce different antibody isotypes, such as IgG, IgA, or IgE. This is important for diversifying the functions of antibodies without altering antigen specificity. It allows for different effector functions, such as opsonization, neutralization, or complement activation. This process does not eliminate antigen-specific B cells, as it maintains the immunological memory. Isotype switching does not directly affect antibody affinity for antigens, which is primarily determined by somatic hypermutation and affinity maturation. It is not limited to producing IgM only, as B cells can switch to other isotypes based on the cytokine microenvironment.