Download Peripherals and Central Thermoreceptors in Physiology - Study Guide | BMS 360 and more Study notes Biology in PDF only on Docsity! 27 March Figure 15.17 – Peripheral and central thermoreceptors Figure 16.12 Objectives Understand the difference between endocrine and exocrine cells/signaling Know the different classes of hormones, and how their physical properties affect their signaling Understand how hormones signal through their receptors Understand how endocrine activity is regulated and the overall layout of the endocrine system Signaling systems in the body Neuronal signaling Endocrine signaling Neuroendocrine signaling Endocrine system Group of secretory cells that release a chemical (hormone) in the bloodstream which acts on a target cell and modulates its activity Functions of endocrine system Maintain optimal biochemical environment in the body (metabolism, homeostasis, water and nutrient balance) Integrate and regulate growth and development Control, maintain, initiate sexual reproduction Hormones “To excite or arouse” Amines – modified amino acids Modified fatty acids Peptide hormones Steroid hormones Amine hormones: structure Tyrosine-derived amine hormones Modified free fatty acids: structure Prostaglandins derived from arachidonic acid (created by action of phospholipase) Arachidonic acid → cyclooxygenase pathways → PGE2 (vasodilation, GI tract muscle), PGF2α (uterine contraction, vasoconstriction), thromboxanes (clotting) Peptide hormones: structure Example: releasing hormones, pituitary hormones, GI tract hormones, pancreatic hormones Peptide Hormone Synthesis, Packaging, and Release Messenger RNA on the ribosomes binds amino acids into a peptide chain called a preprohormone. The chain is directed into the ER lumen by a signal sequence of amino acids. Enzymes in the ER chop off the signal sequence, creating an inactive prohormone. The prohormone passes from the ER through the Golgi apparatus. Secretory vesicles containing enzymes and prohormone bud off the Golgi. The enzymes chop the prohormone into one or more active peptides plus additional peptide fragments. The secretory vesicle releases its contents by exocytosis into the extracellular space.
