Pancreatic islets by scarce alpha, delta and PP cells in the periphery, human islets display alpha and beta cells in close relationship with each other throughout the cluster. Islets can influence each other through paracrine and autocrine communication, and beta cells are coupled electrically to six to seven other beta cells (but not to other cell types). The paracrine feedback system of the pancreatic islets has the following structure: A large number of G protein-coupled receptors (GPCRs) regulate the secretion of insulin, glucagon and somatostatin from pancreatic islets, and some of these GPCRs are the targets of drugs used to treat type-2
Eccrine sweat gland Eccrine sweat gland Eccrine glands (; from "ekkrinein" "secrete"; sometimes called merocrine glands) are the major sweat glands of the human body, found in virtually all skin, with the highest density in palm and soles, then on the head, but much less on the trunk and the extremities. In other mammals, they are relatively sparse, being found mainly on hairless areas such as foot pads. They reach their peak of development in humans, where they may number 200–400/cm² of skin surface. They produce a clear, odorless substance, sweat, consisting primarily of water. Eccrine glands are composed of an intraepidermal spiral