Nokea
Which of the following statements is NOT true?
- A. B cells are important in the defense against extracellular pathogens
- B. The number of memory B cells recognizing antigen X is always smaller than the number of naïve B cells recognizing antigen X, as most specific B cells are killed when the immune response subsides
- C. Memory B cells are B cells differentiated from cells that have encountered the antigen and are long-lived
- D. The B cell repertoire is virtually infinite and includes specificities for any possible antigen
Correct Answer: B
Rationale: The correct answer is B because the statement is false. Memory B cells are formed during an immune response and persist long-term, allowing for a faster and more robust response upon reinfection with the same antigen. The number of memory B cells recognizing an antigen is typically greater than the number of naïve B cells, as they are specifically primed and preserved. In contrast, naïve B cells are naive to the antigen and need to undergo activation and differentiation upon encountering the antigen for the first time. Therefore, statement B is incorrect as it inaccurately suggests that memory B cells are always fewer than naïve B cells recognizing the same antigen.
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A nurse attends a seminar on the immune system and learns about the different lymphocytes in the body. Where do the T lymphocytes originate from and where do they travel to?
- A. Bone marrow and the lymph nodes
- B. Bone marrow and plasma
- C. Bone marrow and spleen
- D. Bone marrow and thymus
Correct Answer: D
Rationale: T lymphocytes originate in the bone marrow and mature in the thymus where they become specialized for immune responses.
Secondary lymphoid tissues are where:
- A. Lymphocyte precursors become mature
- B. Inflammation occurs during re-infection with a given pathogen
- C. Lymphocytes become activated by antigen
- D. Gene rearrangement takes place
Correct Answer: C
Rationale: The correct answer is C because secondary lymphoid tissues, like lymph nodes and spleen, are where lymphocytes encounter antigens and become activated. This process leads to the proliferation and differentiation of lymphocytes, enabling them to mount an immune response against specific pathogens. Choices A, B, and D are incorrect because A pertains to primary lymphoid tissues, B describes a localized immune response, and D refers to the process of gene rearrangement that occurs in the primary lymphoid tissues during lymphocyte development.
What happens when immune complexes are not cleared in Type III hypersensitivity?
- A. They activate T cells
- B. They deposit in tissues, causing inflammation
- C. They are phagocytosed by macrophages without effects
- D. They suppress antibody production
Correct Answer: B
Rationale: The correct answer is B because when immune complexes are not cleared in Type III hypersensitivity, they deposit in tissues, activating complement cascades and causing inflammation. This leads to tissue damage and the recruitment of inflammatory cells.
A: Immune complexes do not directly activate T cells in Type III hypersensitivity.
C: Phagocytosis of immune complexes can lead to cell activation and inflammation.
D: Immune complexes do not suppress antibody production in Type III hypersensitivity.
A common collaborative problem related to both hyperkalemia and hypokalemia is which potential complication?
- A. Seizures
- B. Paralysis
- C. Dysrhythmias
- D. Acute kidney injury
Correct Answer: C
Rationale: Both hyperkalemia and hypokalemia disrupt cardiac conduction, causing dysrhythmias due to their effects on myocardial cell membrane potentials.
After engagement of its pattern recognition receptors what happens to a dendritic cell to enable its role in naïve T cell activation?
- A. Expression of MHC class I molecules begins
- B. Increased uptake of antigens
- C. Expression of the B7 molecule
- D. PAMP-induced proliferation
Correct Answer: C
Rationale: After engagement of pattern recognition receptors, dendritic cells upregulate expression of the B7 molecule, which is essential for co-stimulation of naïve T cells. This step is crucial for activating T cells. MHC class I molecules present antigens to CD8+ T cells, not CD4+ T cells, so choice A is incorrect. Dendritic cells already have high antigen uptake ability, so choice B is not directly related to activation. PAMP-induced proliferation is not a typical response of dendritic cells after pattern recognition receptor engagement, making choice D incorrect.