Which type of pathogen do interferons defend against?

A. NK cells and neutrophils: While NK cells can be found in lymph nodes, neutrophils are not typically housed in lymph nodes; they are more abundant in the bloodstream and tissues during acute inflammation.

B. Lymphocytes and neutrophils: Lymphocytes are indeed housed in lymph nodes, but neutrophils primarily migrate to sites of infection or inflammation rather than residing in lymph nodes.

C. NK cells and complement cells: Natural killer cells can be found in lymph nodes, but complement proteins are not cells; they circulate in the blood and become activated in response to pathogens.

D. Lymphocytes and macrophages: Lymph nodes primarily house lymphocytes (B cells and T cells) and macrophages, which play vital roles in the immune response by filtering lymph and

A. Blood fills the left ventricle and empties the right: This refers to the ventricles, not the atria, so it is incorrect in the context of atrial diastole.

B. Both the left and right atrial chambers fill with blood: During atrial diastole, the atria relax and fill with blood from the veins (superior/inferior vena cava for the right atrium and pulmonary veins for the left atrium).

C. Blood fills the right atrium and empties the left: This is incorrect because both atria fill with blood during atrial diastole.

D. Both the left and right atria are emptied of blood: This describes atrial systole (contraction), not diastole.