ES 207 Lecture 3: endocrine system
6 Nov 2018
School
Department
Course
Professor
Document Summary
Chemical messengers allow cells to communicate with each other to regular body activities: most chemical messengers are produced by a specific collection of cells or by a gland. These messengers affect cells that are distant from their source. The endocrine system is composed of endocrine glands and specialized endocrine cells located throughout the body: endocrine glands and cells secrete minute amounts of chemical messengers called hormones into the bloodstream, rather than into the duct. Hormones travel through the general blood circulation to specific sites called target tissues or effectors, where they produce coordinated response of the target tissues. Lipid soluble hormones: they are nonpolar, and include steroid hormones, thyroid hormones, and fatty acid derivative hormones, such as certain eicosanoids. Water-soluble hormones: polar molecules and they include protein hormones, peptide hormones, and most amino acid derivative hormones. Blood-borne chemicals can directly stimulate the release of some hormones. These are referred to as humoral stimuli because they circulate in the blood.
