One group of proteolytic enzymes secreted by natural killer (NK) cells is _______
granzymes
selectins
cytokines
Interferons
perforins
The Correct Answer is A
A. Granzymes: Granzymes are proteolytic enzymes released by NK cells into target cells after perforin creates entry pores. They trigger apoptosis by activating caspases and degrading intracellular components, allowing NK cells to eliminate virus-infected or cancerous cells efficiently.
B. Selectins: Selectins are adhesion molecules that help leukocytes migrate during inflammation. They are not enzymes and are not secreted by NK cells, as their role involves cell-to-cell binding rather than inducing apoptosis.
C. Cytokines: Cytokines are signaling molecules used for communication within the immune system. Although NK cells secrete cytokines like IFN-γ, cytokines are not proteolytic enzymes and do not directly induce programmed cell death.
D. Interferons: Interferons are antiviral signaling proteins that enhance immune defense, but they are not proteolytic and do not mediate direct killing. NK cells may secrete interferons, yet these are regulatory rather than destructive molecules.
E. Perforins: Perforins create pores in the target cell membrane, enabling granzymes to enter. While essential to NK-cell function, perforins themselves are not proteolytic enzymes, but rather pore-forming proteins.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. Trachea:The trachea is part of the lower respiratory tract. It conducts air from the larynx to the bronchi but is not included in the upper respiratory tract.
B. Larynx:The larynx serves as a passageway for air and houses the vocal cords. It marks the boundary between the upper and lower respiratory tracts rather than being entirely part of the upper tract.
C. Pharynx:The upper respiratory tract extends from the nose and mouth through the pharynx. The pharynx conducts air toward the larynx and serves as a shared pathway for both air and food.
D. Lungs:The lungs are part of the lower respiratory tract, containing bronchi, bronchioles, and alveoli. They are not included in the upper respiratory tract.
E. Alveoli:Alveoli are microscopic air sacs within the lungs where gas exchange occurs. They are part of the lower respiratory tract, not the upper respiratory tract.
Correct Answer is A
Explanation
The immune system spans nearly every organ and tissue in the body because immune cells circulate continuously through the bloodstream and lymphatic system. Lymphoid tissues such as the bone marrow, thymus, lymph nodes, spleen, tonsils, Peyer’s patches, and mucous membranes all play key roles in immune defense. Organs like the skin, lungs, and gastrointestinal tract contain specialized immune cells that detect and respond to pathogens.
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