Endocrine Secretion: Insulin-Producing Beta Cells of Islets of Langerhans

Abstract

Endocrine cells can form distinct organs such as the thyroid and adrenal glands, a microorgan in a larger organ such as the islets of Langerhans in the exocrine pancreas, and exist as single cells dispersed in other organs such as the respiratory and digestive tract. They synthesise, store and secrete polypeptide or steroid hormones, which are important signalling molecules. Endocrine glands secrete their products in the blood circulation through which they are transported to distant target cells. Accordingly, endocrine glands are rich in capillaries. Upon binding of the secreted hormone to its receptor on the target cells, an intracellular signalling cascade is initiated that regulates essential functions such as proliferation, differentiation and metabolism.