All these belong to the second line of defense except
the macrophage system
interferon and the complement system
inflammation
antibodies
natural killer cells
The Correct Answer is D
A. The macrophage system: Macrophages are part of the innate immune system and serve as a second line of defense. They phagocytose pathogens, release cytokines, and help initiate inflammation, providing immediate, non-specific protection.
B. Interferon and the complement system: Interferons and the complement system are innate defense mechanisms. Interferons inhibit viral replication, while the complement system promotes pathogen lysis and opsonization, functioning before adaptive immunity is activated.
C. Inflammation: Inflammation is a key component of the second line of defense. It mobilizes immune cells, increases vascular permeability, and delivers plasma proteins to the site of infection, offering rapid protection against pathogens.
D. Antibodies: Antibodies are produced by B lymphocytes as part of the adaptive immune system. They are a component of the third line of defense and are not part of the innate, second line mechanisms.
E. Natural killer cells: NK cells are innate immune cells that can directly kill virus-infected or abnormal cells. They act rapidly without prior antigen exposure, making them part of the second line of defense.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. All contain valves to prevent the backflow of blood:Valves are present in veins, not arteries. Arteries rely on high pressure generated by the heart to maintain forward blood flow, so valves are generally unnecessary.
B. All carry blood away from the heart:By definition, arteries transport blood away from the heart, regardless of whether the blood is oxygenated or deoxygenated. Pulmonary arteries, for example, carry deoxygenated blood to the lungs, while systemic arteries carry oxygenated blood to tissues.
C. All carry oxygenated blood to the heart:Arteries do not carry blood to the heart; veins do. Additionally, some arteries (like the pulmonary arteries) carry deoxygenated blood away from the heart, so oxygen content is not a defining feature.
D. Only large arteries are lined with endothelium:All arteries, regardless of size, have an endothelial lining (tunica intima). This layer is essential for maintaining a smooth blood flow and regulating vascular functions.
Correct Answer is A
Explanation
A. The flu has several strains that change seasonally:Influenza viruses undergo frequent mutations, leading to new strains each season. Because memory cells from previous vaccinations may not recognize these new strains, annual vaccination is required to provide effective immunity against the current circulating strains.
B. Exposure to flu vaccine produces no memory cells from proliferating B-lymphocytes:The flu vaccine does stimulate memory B cells, but its effectiveness can be reduced due to antigenic variation in the virus. The need for seasonal vaccination is not because memory cells fail to form, but because the virus changes frequently.
C. The polio virus is substantially weaker than the flu virus:The strength or virulence of the virus is not the reason for the difference in vaccination schedules. Polio vaccines induce long-lasting immunity because the virus does not mutate rapidly like influenza.
D. The flu vaccine is substantially weaker than the polio vaccine:Vaccine potency does not explain the need for annual flu shots. The primary reason is the frequent mutation of influenza viruses, not the inherent strength or weakness of the vaccine itself.
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