These are a group of enzymes secreted by natural killer (NK) cells.
cytokines
interferons
selectins
granzymes and perforins
The Correct Answer is D
A. Cytokines: Cytokines are signaling molecules secreted by various immune cells to coordinate immune responses. While NK cells do secrete cytokines to activate other immune cells, cytokines themselves are not the enzymes that directly kill target cells.
B. Interferons: Interferons are proteins released by virus-infected cells that help inhibit viral replication and activate immune responses. They do not directly destroy target cells and are not classified as enzymes secreted by NK cells.
C. Selectins: Selectins are adhesion molecules that mediate the rolling of leukocytes along blood vessel walls during inflammation. They are unrelated to NK cell cytotoxic activity and do not function as killing enzymes.
D. Granzymes and perforins: NK cells secrete granzymes and perforins to induce apoptosis in virus-infected or abnormal cells. Perforins form pores in the target cell membrane, allowing granzymes to enter and trigger programmed cell death, providing a rapid innate immune defense.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Blood vessel diameter:Vessel diameter has the greatest influence on blood flow resistance because resistance is inversely proportional to the fourth power of the radius. Small changes in diameter, especially in arterioles, can dramatically increase or decrease resistance, making it the most significant factor.
B. Blood vessel type:While different types of vessels (arteries, arterioles, capillaries, veins) have structural differences, the type itself does not directly determine resistance as much as the diameter within those vessels.
C. Blood viscosity:Blood viscosity affects resistance, with thicker blood increasing friction. However, normal physiological variations in viscosity are relatively minor compared with the impact of changes in vessel diameter.
D. Total blood vessel length:Longer vessels contribute to higher resistance, but vessel length is generally constant in adults. Therefore, its effect on resistance is less significant than diameter, which can change dynamically through vasoconstriction or vasodilation.
Correct Answer is C
Explanation
A. Increased damage to blood vessel endothelium:Chronic high blood pressure damages the endothelial lining of arteries, promoting atherosclerosis and increasing the risk of vascular complications. This is a common consequence of severe hypertension.
B. Increased incidence of coronary artery disease:Hypertension accelerates plaque formation in coronary arteries and increases cardiac workload, raising the likelihood of developing coronary artery disease. Elevated pressure contributes to vascular injury and ischemic events.
C. Decreased size of the heart muscle:Hypertension typically causes the heart, especially the left ventricle, to undergo hypertrophy (enlargement) due to increased workload. A decrease in heart muscle size does not occur as a result of high blood pressure.
D. Increased work of the left ventricle:High systemic arterial pressure forces the left ventricle to pump against greater resistance, increasing cardiac workload. This elevated work can lead to left ventricular hypertrophy and eventual heart failure if untreated.
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