Nokea
Which opportunistic disease associated with AIDS is characterized by hyperpigmented lesions of skin, lungs, and gastrointestinal (GI) tract?
- A. Kaposi sarcoma
- B. Candida albicans
- C. Herpes simplex type 1 infection
- D. Varicella-zoster virus infection
Correct Answer: A
Rationale: Kaposi sarcoma is a tumor associated with AIDS and manifests as hyperpigmented lesions on the skin, lungs, and GI tract.
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Tay-Sachs disease is an autosomal recessive disease. Both parents have been identified as heterozygous. There is a _____% chance that their offspring will be affected.
- A. 40%
- B. 50%
- C. 20%
- D. 25%
Correct Answer: D
Rationale: For an autosomal recessive disorder where both parents are carriers (heterozygous), there is a 25% chance that their offspring will inherit the condition because each child has a 1-in-4 chance of receiving two copies of the mutated gene.
The intestinal epithelial cells that specialize in the production of antimicrobial peptides are called:
- A. Goblet cells
- B. Enterocytes
- C. Paneth cells
- D. Epithelial stem cells
Correct Answer: C
Rationale: The correct answer is C: Paneth cells. Paneth cells are specialized intestinal epithelial cells located in the small intestine that produce antimicrobial peptides to help defend against pathogens. They play a crucial role in maintaining gut homeostasis. Goblet cells (A) secrete mucus, enterocytes (B) absorb nutrients, and epithelial stem cells (D) are responsible for cell regeneration, but they do not produce antimicrobial peptides like Paneth cells do.
Dendritic cells play a role in:
- A. Costimulation of naïve T cells
- B. Processing of protein antigens to generate peptides
- C. Presentation of peptide-MHC complexes for recognition by T cell receptors
- D. All of the above
Correct Answer: D
Rationale: Dendritic cells play a crucial role in the immune system. Firstly, they provide costimulation to activate naïve T cells (A). Secondly, they process protein antigens into peptides for antigen presentation (B). Finally, dendritic cells present peptide-MHC complexes to T cell receptors for immune response activation (C). Therefore, the correct answer is D, as dendritic cells are involved in all these processes essential for initiating and regulating immune responses. Choices A, B, and C are incorrect as they are individual roles of dendritic cells and do not encompass the full range of functions that dendritic cells perform.
A main cytokine produced by CD4+ TH1 cells is
- A. IL-4
- B. IL-10
- C. IL-5
- D. IFN-γ
Correct Answer: D
Rationale: The correct answer is D: IFN-γ. CD4+ TH1 cells are known to primarily produce interferon-gamma (IFN-γ). This cytokine plays a crucial role in promoting cell-mediated immunity and enhancing the activity of macrophages. IL-4 (choice A) is produced by CD4+ TH2 cells and promotes humoral immunity. IL-10 (choice B) is an anti-inflammatory cytokine produced by various immune cells. IL-5 (choice C) is predominantly produced by CD4+ TH2 cells and is involved in eosinophil activation. Therefore, the main cytokine produced by CD4+ TH1 cells is IFN-γ, making choice D the correct answer.
A 69-year-old woman asks the nurse whether it is possible to 'catch' cancer because many of her friends of the same age have been diagnosed with different kinds of cancer. In responding to the woman, the nurse understands that what factor increases the incidence of tumors in older adults?
- A. An increase in autoantibodies
- B. Decreased activity of the bone marrow
- C. Decreased differentiation of T lymphocytes
- D. Decreased size and activity of the thymus gland
Correct Answer: D
Rationale: The thymus gland shrinks with age, reducing the production of new T cells, which impairs immune surveillance and increases cancer risk.