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Hormone physiology

Here is a little physiology about hormones and how they work in the body...this is for the average trainee who wants to get a better understanding of what goes on inside your body.... Endocrine glands-secrete hormones directly into blood stream, so they are vascular (lots of blood vessels) and ductless. Ductless=no single opening for hormones. Hormone = secreted substance that travel in blood and can effect distant cells These types of Hormone actions are mediated by receptors: -Alter enzyme activity -Alter or induce secretion -Alter membrane permeability -Stimulate mitosis -Alter gene expression (making new protein) Structural Classes of Hormones 1. Amino Acid Derived (it is polar) .Soluble in blood/Cannot cross the membrane 2. Steroid Hormones (cholesterol derived + Thyroid) .Not soluble in blood, so they require carrier proteins/Can cross the plasma membrane .Thyroid derived from amino acids but non-polar Mechanism of hormone action: Steroid + Thyroid 1. Steroid and thyroid hormones alter gene expression (test, estrogen, glucocorticoids) .Steroid and thyroid hormone receptors are part of the group known as ?nuclear receptors?. .They are ligand-dependent transcription factors that can increase of decrease the transcription of a gene. Hormone Activity is closely controlled with (5 methods) 1. Synthesis,-hormones are made when needed-release 2. Activation-the body converts pro-hormones to activate chemical forms 3. Degradation and clearance-enzymes chew up hormones when the job is done. Usually secreted by liver/kidney 4. Storage and release 5. Receptor expression