The glands that secrete hormones comprise the endocrine signaling system. The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell (autocrine or intracrine signalling) or nearby cells (paracrine signalling).
A fen is one of the main types of wetland, the others being grassy marshes, forested swamps, and peaty bogs. Along with bogs, fens are a kind of mire. Fens are usually fed by mineral-rich surface water or groundwater.
Fentanyl (also known as fentanil) is a potent, synthetic opioid pain medication with a rapid onset and short duration of action. It is a potent agonist at Î¼-opioid receptors in the brain. Fentanyl is 50 to 100 times more potent than morphine, but some fentanyl analogues, which are designed to mimic the pharmacological effects of the original drug, may be as much as 10,000 times more potent than morphine.