ENDOCRINE SYSTEM - ia Highlands College：内分泌系统-佐治亚高地学院.ppt

ENDOCRINE SYSTEMTYPES OF GLANDSEndocrineExocrineEndocrine glands; Endocrine tissue?Pineal gland?Pituitary gland?Thyroid gland?Parathyroid glands?Thymus?Adrenal gland?Pancreas?Ovaries / Testes?Stomach?Duodenum?KidneyChemistry of Hormones?Amines - simple hormones synthesized from tyrosine?Proteins and Peptides - chains of amino acids hooked together?Steroids - lipid soluble hormones derived from cholesterol?Eicosanoids - hormones derived from arachidonic acid (from lipids)Mechanisms of Hormone Action?Alters plasma membran permeability?Stimulates synthesis of protein?Activates or deactivates enzymes?Induces secretory activity?Stimulates mitosisLipid Soluble Hormones?Thyroid and steroid hormones cross the cell membrane and bind to INTRACELLULAR receptors in the cytoplasm or nucleus?The hormone- plex triggers activation or inactivation of specific genes?Synthesis of new protein alters cellular activity causing a physiological responseWater Soluble Hormones?Protein and catecholamine hormones act by binding to receptors located on the cell membranes of target cells?Hormones act as the 1st messenger which in turn activates a series of events involving cAMP as the 2nd messenger?cAMP activates protein kinases?G-proteins link the first messenger and the second messengerHormone Release?Humoral - hormones released in response to changing blood levels?Neural - nerve fibers stimulate release?Hormonal - one hormone stimulates the release of another