All of the following are true with respect to IgE molecules, EXCEPT which one?

Correct Answer: C

Rationale: The correct answer is C. IgE molecules do not cross the placenta and fix complement, unlike IgG. IgE is the principal immunoglobulin in allergic reactions (A), mediates anti-parasitic immune responses (B), and triggers the release of histamine and other mediators (D). IgE plays a specific role in allergic responses and defense against parasites. IgG is the main immunoglobulin that crosses the placenta and fixes complement. Therefore, IgE does not share this function.

Correct Answer: B

Rationale: The correct answer is B: Vitamin D. Vitamin D is essential in treating osteoporosis because it helps the body absorb calcium, a crucial mineral for bone health. Without sufficient Vitamin D, the body cannot effectively utilize calcium, leading to weakened bones. Vitamin A (Choice A) is not directly linked to osteoporosis treatment. Vitamin B12 (Choice C) is important for red blood cell production but not specifically for osteoporosis. Vitamin C (Choice D) aids in collagen formation but does not play a primary role in treating osteoporosis.

Correct Answer: B

Rationale: The correct answer is B: Alteration in peripheral circulation. The abductor wedge can affect blood flow to the legs, leading to potential complications like deep vein thrombosis. The nurse should assess for signs of impaired circulation such as color changes, temperature differences, and peripheral pulses. Muscle spasms (A) may occur due to the surgery but are not directly related to the wedge. Compression fracture (C) is not typically a concern with an abductor wedge. Assessing the appropriateness of the wedge size (D) is important but not as critical as monitoring for alterations in peripheral circulation.

Correct Answer: B

Rationale: The correct answer is B because dendritic cells are not only found in lymph nodes but also in tissues. These cells are antigen-presenting cells that capture and present antigens to T cells. A, C, and D are true statements about dendritic cells: A) They are found in tissues, C) They express high levels of MHC molecules for antigen presentation, and D) They are best at activating naive T cells due to their ability to prime adaptive immune responses.

Correct Answer: C

Rationale: The correct answer is C because memory T cells have a lower threshold of activation than naïve T cells. This is because memory T cells have already been primed by previous exposure to antigens, making them more responsive upon re-exposure. This heightened sensitivity allows memory T cells to mount a faster and stronger immune response upon encountering the same antigen again. Choice A is incorrect because memory T cells primarily reside in peripheral tissues and not in secondary lymphoid tissues. Choice B is incorrect because memory T cells have encountered antigens before. Choice D is incorrect because memory T cells exist in a lower frequency compared to naïve T cells due to clonal expansion during the primary immune response.