What catches inhaled particles in the trachea?

A. Proximal convoluted tubule: The proximal convoluted tubule is the main site of creatinine secretion as well as the reabsorption of nutrients and water.

B. Distal convoluted tubule: While secretion occurs here, it is not the main site for creatinine; this site mainly adjusts the final urine concentration.

C. Collecting duct: This part primarily deals with water and electrolyte balance but is not the main site for creatinine secretion.

D. Loop of Henle: This structure plays a key role in water and sodium balance but does not play a significant role in creatinine secretion.

A. Producing early induced proteins: While natural killer cells can produce cytokines, their primary function is not related to protein production.

B. Promoting opsonization of bacteria cells: Opsonization is primarily performed by antibodies and complement proteins, rather than natural killer cells.

C. Secreting signaling molecules: While natural killer cells do secrete signaling molecules (cytokines) to communicate with other immune cells, their main role is the direct destruction of infected cells.

D. Destroying virally infected cells: The primary function of natural killer cells is to recognize and eliminate virally infected cells and tumor cells, contributing to the innate immune response.