Nokea
Which of the following immunoglobulins is present normally in plasma at the highest concentration?
- A. IgG
- B. IgM
- C. IgA
- D. IgD
Correct Answer: A
Rationale: The correct answer is A: IgG. IgG is the most abundant immunoglobulin in plasma, comprising around 75% of total immunoglobulins. It is produced in response to infections and provides long-term immunity. IgM is the first antibody produced in response to an infection, but its concentration decreases over time. IgA is mainly found in mucosal areas and secretions. IgD is present in small amounts and its function is not fully understood. Thus, IgG is the correct answer due to its high concentration in plasma and important role in long-term immunity.
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Benefits from the human microbiome include all the following except:
- A. Out-competition of pathogenic species
- B. Production of important metabolites called short chain fatty acids
- C. Secretion of enzymes such as lysozyme that degrade the cell wall of pathogenic species
- D. Provision of signals leading to the development of the gut-associated immune system
Correct Answer: C
Rationale: The correct answer is C because the human microbiome does not secrete enzymes like lysozyme; instead, lysozyme is produced by the human body. A is correct as the microbiome can out-compete harmful bacteria. B is correct as the microbiome produces short chain fatty acids. D is correct as the microbiome helps in the development of the gut-associated immune system. Therefore, C is the only option that does not accurately describe a benefit from the human microbiome.
What do pattern recognition receptors (PRRs) identify?
- A. Specific antigens
- B. Pathogen-associated molecular patterns (PAMPs)
- C. Host self-proteins
- D. Specific viruses only
Correct Answer: B
Rationale: Pattern recognition receptors (PRRs) identify Pathogen-associated molecular patterns (PAMPs) because PAMPs are unique molecules found on pathogens that trigger an immune response. PRRs recognize these patterns to distinguish between self and non-self. This recognition is crucial for initiating an immune response against potential threats. Specific antigens (A) and specific viruses only (D) are too narrow in scope as PRRs are designed to detect a wide range of patterns. Host self-proteins (C) are recognized by other mechanisms in the immune system to prevent autoimmunity.
Priority Decision: On assessment of a central venous access device (CVAD) site, the nurse observes that the transparent dressing is loose along two sides. What should the nurse do immediately?
- A. Wait and change the dressing when it is due
- B. Tape the two loose sides down and document
- C. Apply a gauze dressing over the transparent dressing and tape securely
- D. Remove the dressing and apply a new transparent dressing using sterile technique
Correct Answer: D
Rationale: Loose dressings increase infection risk; replacing the dressing with sterile technique ensures safety.
A co-receptor on target cells for HIV is
- A. gp120
- B. CR4
- C. CR5
- D. CXCR4
Correct Answer: D
Rationale: The correct answer is D: CXCR4. CXCR4 is a chemokine receptor that serves as a co-receptor for HIV entry into target cells. Step 1: HIV binds to CD4 receptor on the target cell. Step 2: The viral envelope protein gp120 then interacts with either CXCR4 or CCR5 co-receptor to facilitate viral entry. Step 3: In the case of CXCR4-tropic HIV strains, CXCR4 is the co-receptor used for entry into the target cell. Therefore, choice D is correct. Choices A (gp120) and C (CR5) are incorrect as they are not co-receptors, while choice B (CR4) is not a known co-receptor for HIV entry.
Which of the following statements is NOT true
- A. During T cell development the decision to become a CD4 or a CD8 positive cell is a random event
- B. During T cell differentiation the decision to become a TH1 or a TH2 cell CD4+ is a random event
- C. TH2 CD4+ cells secrete IL-4
- D. IL-10 is TH2 polarizing cytokine
Correct Answer: B
Rationale: The correct answer is B: During T cell differentiation, the decision to become a TH1 or a TH2 cell CD4+ is not a random event. This is because T cell differentiation into TH1 or TH2 cells is guided by specific signals from the environment, such as cytokines present during activation. TH1 cells are induced by IL-12 and IFN-gamma, while TH2 cells are induced by IL-4. This process is not random but rather a result of specific signaling cues.
A: During T cell development, the decision to become a CD4 or a CD8 positive cell is not a random event. It is determined by interactions with thymic stromal cells and the T cell receptor.
C: TH2 CD4+ cells do secrete IL-4, so this statement is true.
D: IL-10 is not a TH2 polarizing cytokine; rather, it is known to have regulatory functions in immune responses.