Nokea
Which pathway of the complement system involves properdin, Factor B, and Factor D?
- A. Classical pathway
- B. Alternative pathway
- C. Lectin pathway
- D. Terminal pathway
Correct Answer: B
Rationale: The correct answer is B: Alternative pathway. This pathway involves properdin, Factor B, and Factor D. Properdin stabilizes the C3 convertase complex formed by Factor B and Factor D, leading to the amplification of the complement cascade. The other choices are incorrect because:
A: Classical pathway is initiated by antigen-antibody complexes binding to C1q.
C: Lectin pathway is activated by lectins binding to carbohydrates on pathogen surfaces.
D: Terminal pathway involves the formation of the membrane attack complex.
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All of the following are true with respect to IgM antibodies EXCEPT which one
- A. they fix complement
- B. they occur on the surface of lymphocytes
- C. they predominate in the primary response to antigen
- D. mediate allergic reactions
Correct Answer: D
Rationale: The correct answer is D. IgM antibodies do not mediate allergic reactions. IgE antibodies are responsible for allergic reactions. IgM antibodies fix complement, occur on the surface of lymphocytes, and predominate in the primary response to antigens. IgM is the first antibody produced in response to an infection, playing a key role in the activation of the complement system. IgM antibodies are mainly found in the blood and lymphatic system, not on the surface of lymphocytes. IgE antibodies are the primary mediators of allergic reactions by triggering the release of histamine and other inflammatory molecules.
Which of the following statement concerning Influenza infection is NOT true?
- A. There is evidence that the infection is less common in spring/summer because the transmission of bigger droplets formed at higher temperatures requires more close contact among people
- B. People infected with Flu can spread the disease before becoming symptomatic
- C. The human strains infect cells of the respiratory tract and also extensively infect epithelial cells throughout the body, explaining the systemic symptoms of influenza
- D. The virus hemagglutinin (HA) allows cell infection via the binding to sialic acid on carbohydrates expressed on host cells
Correct Answer: C
Rationale: The correct answer is C because it states that human strains of Influenza extensively infect epithelial cells throughout the body, which is not true. Influenza primarily infects cells of the respiratory tract, leading to respiratory symptoms. Systemic symptoms such as fever, fatigue, and muscle aches are more related to the body's immune response rather than widespread infection of epithelial cells throughout the body. This statement is incorrect as it misrepresents the pathogenesis of Influenza. Choices A, B, and D are incorrect because they are all true statements supported by scientific evidence regarding Influenza transmission, asymptomatic spread, and viral entry mechanism, respectively.
A patient with chronic hepatitis C has been receiving interferon alfa-2a (Roferon-A) injections for the last month. Which information gathered during a visit in the home to conduct an interview and physical assessment is most important to communicate to the physician?
- A. The patient has chronic nausea and vomiting.
- B. The patient is giving the medication by the IM route to her lateral thigh.
- C. The patient has a temperature of 99.7°F orally.
- D. The patient complains of chronic fatigue,muscle aches and anorexia.
Correct Answer: A
Rationale: Chronic nausea and vomiting can lead to dehydration and malnutrition which are serious complications that need to be addressed. While the other symptoms are common side effects of interferon therapy they are less urgent than persistent nausea and vomiting.
Which of the following best describes the immune system's role in tissue regeneration?
- A. Preventing pathogen invasion
- B. Promoting wound healing and cell debris elimination
- C. Increasing cytokine production
- D. Suppressing adaptive immunity
Correct Answer: B
Rationale: The correct answer is B because the immune system plays a crucial role in promoting wound healing and eliminating cell debris. When tissue is damaged, the immune response helps remove dead cells and debris, initiates the healing process, and supports tissue regeneration. This involves the recruitment of immune cells to the site of injury, releasing growth factors to stimulate cell proliferation, and resolving inflammation.
Choice A (Preventing pathogen invasion) is incorrect because while the immune system does play a role in preventing pathogen invasion, this is not directly related to tissue regeneration.
Choice C (Increasing cytokine production) is incorrect because although cytokines are involved in the immune response and can influence tissue repair, simply increasing cytokine production does not fully describe the immune system's role in tissue regeneration.
Choice D (Suppressing adaptive immunity) is incorrect because suppressing adaptive immunity would hinder rather than promote tissue regeneration, as adaptive immunity plays a role in immune memory and long-term protection against pathogens.
Which of the following sentences is NOT true about type I hypersensitivity reactions?
- A. Symptoms manifest in allergic individuals only after a second encounter with an allergen
- B. Food allergies can result in systemic anaphylaxis
- C. TH2 lymphocytes are involved in their development
- D. They can be classified as genetic disorders because they are caused by a single gene defect
Correct Answer: D
Rationale: Step 1: Type I hypersensitivity reactions are immediate allergic reactions that occur upon initial exposure to an allergen, not just after a second encounter.
Step 2: Food allergies can lead to systemic anaphylaxis due to the rapid release of mediators like histamine.
Step 3: TH2 lymphocytes play a crucial role in the development of type I hypersensitivity reactions by promoting IgE production.
Step 4: Type I hypersensitivity reactions are not generally classified as genetic disorders since they result from an immune response to allergens, not a single gene defect.