Nokea
In mice, mutations of which of the following genes cause the 'scurfy' phenotype (scaly skin and multiple autoimmune disorders)?
- A. FOXP3
- B. AIRE
- C. NFkB
- D. IRF
Correct Answer: A
Rationale: Rationale:
1. FOXP3 gene encodes a transcription factor crucial for regulatory T cells function.
2. Mutations in FOXP3 lead to dysfunctional regulatory T cells, causing autoimmune disorders.
3. Scurfy phenotype matches the symptoms of autoimmune disorders seen with FOXP3 mutations.
Summary:
- B (AIRE): AIRE mutations cause autoimmune polyendocrine syndrome, not scurfy phenotype.
- C (NFkB): NFkB is a transcription factor involved in immune response but not linked to scurfy phenotype.
- D (IRF): IRF is a regulator of interferon signaling, not directly associated with scurfy phenotype.
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The nurse is performing an assessment on the patient who is in bilateral Buck traction. Which finding indicates the need to reposition the patient?
- A. The patient's heels are not touching the surface of the mattress.
- B. The elastic bandages need to be revrapped.
- C. The patient's feet are against the footboard.
- D. The weights are hanging free.
Correct Answer: C
Rationale: The correct answer is C because if the patient's feet are against the footboard in Buck traction, it can cause pressure ulcers and compromise circulation. Repositioning the patient is necessary to ensure proper alignment and prevent complications.
Incorrect choices:
A: The patient's heels not touching the mattress can be due to the traction pulling the legs in a specific position.
B: Rewrapping the elastic bandages may be necessary for proper traction maintenance but doesn't indicate immediate need for repositioning.
D: The weights hanging free is a normal finding in Buck traction and indicates proper traction application.
What is the primary characteristic of a secondary immune response?
- A. It is slower and less specific
- B. It is faster, stronger, and more specific
- C. It produces only IgM antibodies
- D. It does not involve memory cells
Correct Answer: B
Rationale: The primary characteristic of a secondary immune response is that it is faster, stronger, and more specific. This is because memory cells generated during the primary response allow for a quicker and more efficient recognition and response to the same antigen upon re-exposure. This results in a faster production of antibodies, a stronger immune response, and increased specificity. Choice A is incorrect as secondary responses are actually faster and more specific. Choice C is incorrect as secondary responses can produce IgG antibodies in addition to IgM. Choice D is incorrect because memory cells are essential for secondary immune responses.
What is the primary role of Helper T cells in the immune response?
- A. Killing infected host cells
- B. Producing antibodies
- C. Secreting cytokines to activate other immune cells
- D. Suppressing immune responses
Correct Answer: C
Rationale: Helper T cells primarily secrete cytokines to activate other immune cells. This is crucial for coordinating and amplifying the immune response. They do not kill infected host cells (A), as that is the role of cytotoxic T cells. Producing antibodies (B) is the function of B cells. Suppressing immune responses (D) is the role of regulatory T cells, not Helper T cells.
A major effector function of TH2 cells is:
- A. Protection against intracellular bacteria
- B. Protection against parasitic worms
- C. Regulation of the adaptive immune response through the secretion of anti-inflammatory cytokines
- D. Activation of macrophages
Correct Answer: B
Rationale: The correct answer is B because TH2 cells play a crucial role in protecting against parasitic worms by secreting cytokines that promote eosinophil activation and antibody production. This response helps to expel the parasites from the body.
Incorrect choices:
A: TH1 cells are responsible for protection against intracellular bacteria.
C: TH3 cells, not TH2 cells, are known for secreting anti-inflammatory cytokines.
D: Activation of macrophages is primarily mediated by TH1 cells through IFN-gamma secretion.
What is the function of MHC molecules on antigen-presenting cells?
- A. Secreting cytokines
- B. Binding and destroying pathogens
- C. Displaying antigen fragments for T cell recognition
- D. Producing antibodies
Correct Answer: C
Rationale: The correct answer is C, displaying antigen fragments for T cell recognition. MHC molecules bind to antigen fragments and present them on the cell surface for T cells to recognize. This process is crucial for activating the immune response. Choice A is incorrect as MHC molecules do not secrete cytokines. Choice B is incorrect as MHC molecules do not directly destroy pathogens. Choice D is incorrect as MHC molecules do not produce antibodies; that is the function of B cells.