The interaction of a TCR with its specific antigen is denoted as "signal 1" of activation and does NOT need the contribution of which of the following components
- A. TCR α-chain
- B. TCR β-chain
- C. 28
- D. MHC molecule
Correct Answer: C
Rationale: Step-by-step rationale:
1. "Signal 1" activation requires TCR to interact with its specific antigen.
2. TCR consists of α and β chains, which are essential for antigen recognition.
3. MHC molecule is crucial for presenting antigens to TCR for recognition.
4. Choice C (28) is not a component involved in TCR-antigen interaction.
5. Therefore, the correct answer is C as it does not contribute to "signal 1" activation.
Summary:
A and B are incorrect as TCR α and β chains are necessary for antigen recognition.
D is incorrect as MHC molecule is essential for presenting antigens to TCR.
C is correct as it is not involved in the TCR-antigen interaction process.
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Select incorrect mechanism for the development of autoimmune disorder.
- A. A second exposure to an allergen.
- B. Cross-reaction of antibodies formed against foreign antigens with self-antigens.
- C. Exposure of previously 'hidden' self-antigens to the adaptive immune system.
- D. Mutation followed by the appearance of membrane proteins not previously present.
Correct Answer: A
Rationale: The correct answer is A. A second exposure to an allergen does not lead to the development of autoimmune disorders. The key mechanisms involved in autoimmune disorders are self-tolerance breakdown and immune system attacking self-antigens.
Explanation:
1. B: Cross-reaction of antibodies formed against foreign antigens with self-antigens is a possible mechanism for autoimmune disorders.
2. C: Exposure of previously 'hidden' self-antigens to the adaptive immune system can trigger autoimmune responses.
3. D: Mutation followed by the appearance of membrane proteins not previously present can lead to autoimmune disorders, as the immune system may recognize these proteins as foreign.
Summary:
Choice A is incorrect because a second exposure to an allergen does not cause the immune system to target self-antigens, which is the hallmark of autoimmune disorders. Choices B, C, and D are more plausible mechanisms for the development of autoimmune disorders.
The clonal selection theory explains:
- A. That one given lymphocyte expresses multiple antigen receptors with different specificity
- B. That antigens influence the generation of antigen receptors during lymphocyte development
- C. How the immune response to an antigen increases the number of lymphocytes specific for that antigen
- D. The increase in blood neutrophils observed during bacterial infections
Correct Answer: C
Rationale: Rationale:
1. Clonal selection theory states that specific lymphocytes are activated by antigens.
2. Upon activation, these lymphocytes proliferate to form a clone of cells specific to the antigen.
3. This increases the number of lymphocytes specific for the antigen.
4. Choice C correctly aligns with the essence of clonal selection theory.
Summary:
A: Incorrect - Clonal selection theory does not involve a single lymphocyte expressing multiple antigen receptors.
B: Incorrect - Antigens do not influence the generation of antigen receptors, but rather activate specific lymphocytes.
D: Incorrect - Clonal selection theory focuses on lymphocyte response to antigens, not neutrophil increase during infections.
Which of the following is necessary to produce a T-cell repertoire capable of interacting with self MHC molecules?
- A. Two of these responses are correct
- B. Positive selection
- C. Negative selection
- D. Induction of energy
Correct Answer: B
Rationale: Positive selection is necessary to produce a T-cell repertoire capable of interacting with self MHC molecules. During positive selection in the thymus, T-cells that can recognize self MHC molecules are retained, ensuring self-tolerance and functionality. Negative selection eliminates self-reactive T-cells. Induction of anergy is a state of T-cell unresponsiveness and does not contribute to the development of a functional T-cell repertoire. Choice A is incorrect as only positive selection is necessary for self MHC recognition.
A patient with advanced AIDS has a nursing diagnosis of impaired memory related to neurologic changes. In planning care for the patient, what should the nurse set as the highest priority?
- A. Maintain a safe patient environment
- B. Provide a quiet, nonstressful environment to avoid overstimulation
- C. Use memory cues such as calendars and clocks to promote orientation
- D. Provide written instructions of directions to promote understanding and orientation
Correct Answer: A
Rationale: Safety is paramount for cognitively impaired patients. Preventing falls and ensuring access to necessities takes precedence over other interventions.
Which of the following about Influenza virus is NOT correct
- A. It's an RNA virus
- B. In humans influenza infects the lung epithelial cells
- C. Release of newly formed virus from the infected cell is mediated by Hemagglutinin (HA)
- D. Tamiflu is a Neuraminidase (NA) inhibitor
Correct Answer: C
Rationale: The correct answer is C because the release of newly formed virus from the infected cell is actually mediated by Neuraminidase (NA), not Hemagglutinin (HA).
1. Influenza virus is indeed an RNA virus (Choice A).
2. In humans, influenza primarily infects lung epithelial cells (Choice B).
3. Hemagglutinin (HA) helps the virus enter host cells, while Neuraminidase (NA) helps release viral particles from infected cells (Choice C is incorrect).
4. Tamiflu is a Neuraminidase (NA) inhibitor, which prevents the release of viral particles, aiding in the treatment of influenza infections (Choice D).