PNB 2264 Lecture Notes - Lecture 17: Adrenal Medulla, Endocrine System, Cell Growth
17 Dec 2018
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Document Summary
Endocrine system - a chemical messenger system within the body. Coordinate essential processes within the body by effecting changes at the cellular level. Endocrine systems do not secrete into ducts, but directly into the bloodstream. Decentralized - the endocrine system can have systemic effects because blood goes everywhere. One cell to one (or several) cells. Secreted directly from neurons into the bloodstream. Over 50 different hormones used within the body that vary by: Genes encode for this hormone because it is a protein. Ex) insulin made in the pancreas, releasing hormones, glucagon. Encoding for a protein can take a long time which is a problem if you need a hormone. Synthesized as preprohormones (very long inactive chains) Processed (cleaved) to become prohormones (long inactive chains) Cleaved to become hormones (short active chains) Ex) sex steroids (estrogen, progesterone, testosterone), cortical steroids (cortisol, aldosterone) Cellular enzymes modify cholesterol to produce different biologically active hormones. Ex) thyroid hormones, catecholamines (epinephrine, norepinephrine, dopamine)
