Nokea
Which compounds produced by microorganisms can cause fever in humans and can withstand autoclaving?
- A. endotoxin
- B. Lipid A
- C. lipopolysaccharide
- D. peptidoglycan
Correct Answer: D
Rationale: The correct answer is D, peptidoglycan. Peptidoglycan is a component of bacterial cell walls that can trigger fever in humans. It is a sturdy molecule that can withstand autoclaving.
A: Endotoxin is a component of the outer membrane of Gram-negative bacteria, not resistant to autoclaving.
B: Lipid A is the toxic component of endotoxin, not resistant to autoclaving.
C: Lipopolysaccharide is the major component of the outer membrane of Gram-negative bacteria, not resistant to autoclaving.
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During an adaptive immune response to a pathogen an important outcome of the clonal selection process is:
- A. An increase in the number of lymphocytes specific for the pathogen that activated the response
- B. Elimination of lymphocytes that are not specific for the pathogen that activated the response
- C. An increase in the number of antigen receptor specificities expressed by each lymphocyte
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A because during clonal selection, lymphocytes specific to the pathogen are activated, leading to their proliferation and differentiation into effector cells. This results in an increase in the number of lymphocytes specific for the pathogen, enhancing the immune response.
Choice B is incorrect because clonal selection does not involve the elimination of non-specific lymphocytes but rather the expansion of specific lymphocytes.
Choice C is also incorrect because clonal selection does not change the antigen receptor specificities expressed by lymphocytes but instead focuses on expanding the population of lymphocytes with receptors specific to the pathogen.
Therefore, the correct outcome of clonal selection is the increase in the number of lymphocytes specific for the pathogen that activated the response, making choice A the most accurate option.
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 role of complement component C3b in immune responses?
- A. Initiates MAC formation
- B. Acts as an opsonin to enhance phagocytosis
- C. Triggers inflammation
- D. Neutralizes cytokines
Correct Answer: B
Rationale: The correct answer is B: C3b acts as an opsonin to enhance phagocytosis. C3b binds to pathogens and enhances their recognition by phagocytic cells, facilitating their engulfment and destruction. This process is crucial for efficient immune responses. A, MAC formation, is initiated by the membrane attack complex, not C3b. C, inflammation, is triggered by various mediators such as histamine and cytokines, not C3b. D, neutralizing cytokines, is not a function of C3b; cytokines are regulatory proteins involved in immune responses.
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.
While caring for an HIV-positive patient who is hospitalized with Pneumocystis carinii pneumonia,you note that all of these drug therapies are scheduled for 10:00 AM. Which nursing action is most essential to accomplish at the scheduled time?
- A. Administer the protease inhibitor indinavir (Crixivan) 800 mg PO.
- B. Infuse pentamidine (Pentam-300) 300 mg IV over 60 minutes.
- C. Have the patient “swish and swallow” nystatin (Mycostatin) 5 mL.
- D. Apply acyclovir (Zovirax) cream to oral herpes simplex lesions.
Correct Answer: B
Rationale: Pentamidine is a critical medication for treating Pneumocystis carinii pneumonia and must be administered on time to ensure therapeutic levels. The other medications while important can be administered slightly later if necessary without significantly impacting the patient’s condition.