Nokea
Which patient is at risk for hypernatremia?
- A. Has a deficiency of aldosterone
- B. Has prolonged vomiting and diarrhea
- C. Receives excessive IV 5% dextrose solution
- D. Has impaired consciousness and decreased thirst sensitivity
Correct Answer: D
Rationale: Impaired consciousness leads to decreased thirst sensitivity, preventing adequate water intake and increasing sodium concentration in the blood.
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What is the correct order of steps needed for 2nd generation sequencing?
- A. DNA fragmentation, DNA isolation, amplification, primer ligation, sequencing
- B. Amplification, primer ligation, sequencing, DNA fragmentation, DNA isolation
- C. DNA isolation, DNA fragmentation, primer ligation, amplification, sequencing
- D. Sequencing, DNA isolation, DNA fragmentation, primer ligation, amplification
Correct Answer: C
Rationale: The correct order of steps for 2nd generation sequencing is C: DNA isolation, DNA fragmentation, primer ligation, amplification, sequencing. Firstly, DNA isolation is crucial to extract the DNA from the sample. Next, DNA fragmentation breaks the DNA into smaller fragments for sequencing. Primer ligation involves attaching primers to the DNA fragments. Amplification is necessary to make multiple copies of the DNA fragments for sequencing. Finally, sequencing is the process of determining the nucleotide sequence of the DNA fragments. This order ensures that the DNA is properly prepared and amplified before sequencing, leading to accurate results.
Choices A, B, and D are incorrect because they do not follow the correct sequence of steps required for 2nd generation sequencing. Incorrect sequences may lead to errors in the sequencing process and inaccurate results.
What underpins most functions of the immune system?
- A. Secondary lymphoid tissues
- B. Haematopoietic stem cells in the bone marrow
- C. Mucosal immune system activity
- D. Rapid cytokine suppression
Correct Answer: B
Rationale: The correct answer is B: Haematopoietic stem cells in the bone marrow. These cells are responsible for generating all immune cells, including lymphocytes, macrophages, and dendritic cells. They continuously replenish the immune system, allowing for proper immune function. Secondary lymphoid tissues (choice A) play a role in immune responses but are not the primary underpinning. Mucosal immune system activity (choice C) is important for defense at mucosal surfaces but is not the foundation of immune function. Rapid cytokine suppression (choice D) is a regulatory mechanism, not the fundamental basis of immune system functions.
Human immunodeficiency virus (HIV) infects:
- A. CD4+ T cells
- B. B cells
- C. CD8+ T cells
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A: CD4+ T cells. HIV primarily infects CD4+ T cells by binding to the CD4 receptor and a co-receptor, usually CCR5 or CXCR4. CD4+ T cells are crucial for coordinating the immune response. B cells (choice B) are not typically infected by HIV. CD8+ T cells (choice C) can be indirectly affected by HIV, but they are not the primary target of the virus. Therefore, the correct choice is A as it accurately reflects the primary target cells of HIV infection.
APECED is a rare autoimmune disease caused by deficiency of
- A. CTLA-4
- B. AIRE
- C. Tregs
- D. TGF-β
Correct Answer: B
Rationale: The correct answer is B: AIRE. APECED (Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy) is caused by mutations in the AIRE gene. AIRE is responsible for regulating the expression of self-antigens in the thymus, crucial for the development of immune tolerance. Deficiency in AIRE leads to the production of autoantibodies and autoimmune manifestations.
Incorrect options:
A: CTLA-4 is involved in downregulating immune responses but is not directly linked to APECED.
C: Tregs (regulatory T cells) play a role in immune tolerance, but APECED is not directly caused by their deficiency.
D: TGF-β is a cytokine involved in immune regulation, but its deficiency does not lead to APECED.
What is the primary function of anaphylotoxins (e.g., C3a, C4a, C5a) in the immune system?
- A. Suppressing inflammation
- B. Facilitating antigen presentation
- C. Inducing inflammation and recruiting immune cells
- D. Neutralizing pathogens
Correct Answer: C
Rationale: The correct answer is C: Inducing inflammation and recruiting immune cells. Anaphylotoxins, such as C3a, C4a, and C5a, are small molecules that are released during complement activation. They play a crucial role in enhancing inflammation by attracting immune cells to the site of infection or injury.
1. Anaphylotoxins induce inflammation by stimulating the release of histamine and other inflammatory mediators.
2. They promote vasodilation and increase vascular permeability, allowing immune cells to easily reach the affected area.
3. Anaphylotoxins also act as chemoattractants, recruiting neutrophils, macrophages, and other immune cells to the site of inflammation to help fight against pathogens.
4. These molecules do not suppress inflammation (choice A), facilitate antigen presentation (choice B), or neutralize pathogens (choice D). Their primary function is to amplify the immune response by inducing inflammation and recruiting immune cells to combat infections