Nokea
CD3 is a complex of proteins involved in
- A. Antigen binding
- B. Signal propagation in T cells
- C. Signal propagation in B cells
- D. T cell homing to lymph nodes
Correct Answer: B
Rationale: The correct answer is B: Signal propagation in T cells. CD3 is a protein complex found on the surface of T cells that is crucial for T cell receptor signaling and activation. It helps propagate signals within T cells, leading to T cell activation and immune responses. Choice A (Antigen binding) is incorrect as CD3 is not directly involved in antigen binding. Choice C (Signal propagation in B cells) is incorrect as CD3 is specific to T cells, not B cells. Choice D (T cell homing to lymph nodes) is incorrect as CD3 is not responsible for the physical migration of T cells to lymph nodes.
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A patient with a genetic mutation of BRCA1 and a family history of breast cancer is admitted to the surgical unit where she is scheduled that day for a bilateral simple mastectomy. What is the reason for this procedure?
- A. Prevent breast cancer
- B. Diagnose breast cancer
- C. Cure or control breast cancer
- D. Provide palliative care for untreated breast cancer
Correct Answer: A
Rationale: A bilateral simple mastectomy is performed to prevent breast cancer in high-risk individuals with BRCA1 mutations.
Emphysema is characterized by ______.
- A. the loss of elasticity of the lungs
- B. spasms of the bronchioles due to exposure to allergens
- C. abnormal growth of epithelial cells that line the bronchioles
- D. excessive mucus production in the lower respiratory pathways
Correct Answer: A
Rationale: Rationale:
A: Emphysema is characterized by the destruction of alveolar walls and loss of elasticity of the lungs, leading to air trapping and difficulty exhaling. This results in reduced gas exchange and airflow limitation.
B: Bronchospasms are more commonly associated with conditions like asthma, not emphysema.
C: Abnormal growth of epithelial cells is seen in conditions like lung cancer, not emphysema.
D: Excessive mucus production is characteristic of conditions like chronic bronchitis, not emphysema.
Summary: The correct answer is A because emphysema specifically involves the loss of elasticity of the lungs due to destruction of alveoli, leading to impaired airflow. Choices B, C, and D are incorrect as they describe features more indicative of other respiratory conditions.
A critical role of secondary lymphoid tissues is to:
- A. Provide a place for B and T lymphocytes to mature and begin expression of antigen receptors
- B. Allow co-localization of the components required to activate naïve lymphocytes
- C. Minimize contact of naïve lymphocytes with self antigens
- D. All of the above
Correct Answer: B
Rationale: Step 1: Secondary lymphoid tissues bring together antigen-presenting cells and lymphocytes, facilitating the activation of naïve lymphocytes.
Step 2: Co-localization of these components is essential for efficient immune response initiation.
Step 3: Maturation and expression of antigen receptors primarily occur in primary lymphoid tissues, not secondary.
Summary:
A: Incorrect. Maturation of lymphocytes occurs mainly in primary lymphoid tissues.
C: Incorrect. Contact with self-antigens is necessary for self-tolerance and occurs in primary lymphoid tissues.
D: Incorrect. Only choice B accurately describes the critical role of secondary lymphoid tissues.
All of the following are true of antigen EXCEPT which one of the following?
- A. They contain paratopes
- B. They will react with antibodies.
- C. They contain antigenic determinants.
- D. They can elicit an immune response.
Correct Answer: A
Rationale: The correct answer is A. Paratopes are actually parts of antibodies that bind to antigens, not the antigens themselves. A is incorrect because antigens do not contain paratopes; rather, they contain epitopes or antigenic determinants that are recognized by antibodies. B, C, and D are true statements about antigens. B is true because antigens react with antibodies. C is true because antigens contain antigenic determinants that antibodies recognize. D is true because antigens can elicit an immune response by stimulating the production of antibodies. Therefore, the correct answer is A because antigens do not contain paratopes.
What dietary advice should the nurse give to clients with HIV/AIDS?
- A. Encourage intake of fat-soluble vitamins in amounts two to five times the RDA
- B. Encourage intake of water-soluble vitamins in amounts two to five times the RDA
- C. Increase the intake of iron and zinc
- D. Decrease the intake of trace element and antioxidant supplements
Correct Answer: B
Rationale: Water-soluble vitamins are crucial for immune function and are often depleted in HIV/AIDS patients so increasing their intake is beneficial.