Letâs start with military unmanned aircraft. According to the annual almanac published by the Air Force Association (http://www.airforcemag.com/Magaz...), as of mid-2016: MQ-1 Predators: 268 produced, 139 in service, 111 destroyed in accidents; MQ-9 Reapers: 346 (including those as yet undelivered), 165 in service, 24 destroyed in accidents
Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland.In contrast to excretion, the substance may have a certain function, rather than being a waste product.ecretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland.
Secretion is an active process. In the kidney tubules, somethings, like K+ is secreted from the peritubular capillaries, into tubular cells, and then out into the lumen to mix with the fluid. Excretion is passive. What is excreted by the kidneys is everything that is not reabsorbed and what is secreted.