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Endocrine System. “Raging Hormones!”. Endocrine System. Odd organ system Compare to nervous sys., digestive sys. Endocrine glands usually not connected Considered a “system” because of functional similarity. Endocrine System. Endocrine glands Masses of epithelial tissue
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Endocrine System “Raging Hormones!” Endocrine-System.ppt
Endocrine System • Odd organ system • Compare to nervous sys., digestive sys. • Endocrine glands usually not connected • Considered a “system” because of functional similarity Endocrine-System.ppt
Endocrine System • Endocrine glands • Masses of epithelial tissue • Cells secrete into interstitial spaces, • Secretions (hormones) diffuse into blood • No ducts! • Contrast to exocrine glands Endocrine-System.ppt
Endocrine System • “Hormone” • Chemical messenger secreted into blood and carried to “target cells” where it alters activity. • Other chemical messengers • Autocrines • Paracrines Endocrine-System.ppt
Hormones • 3-4 Chemical Types • Steroids • Amines • Peptides • (Eicosanoids) • Mostly paracrines • Leukotrienes • Prostaglandins Endocrine-System.ppt
Hormones • Steroids • Derivatives of cholesterol • Four covalently-bonded rings • Adrenal cortex • Gonads Endocrine-System.ppt
Hormones • Amines • Derivatives of tyrosine, an amino acid • Thyroid hormones • Thyroxine (T4) • Triiodothyronine (T3) • Adrenal medulla • Epinephrine • Norepinephrine • Usually neurotransmitter Endocrine-System.ppt
Hormones • Peptides • “Chains” of amino acids • 4 – 200+ amino acids • Hypothalamus • Pituitary (Ant. & Post.) • Islets of Langerhans • Parathyroid hormone • Digestive system hormones Endocrine-System.ppt
Mechanisms of Hormone Action • Lipid-soluble steroids & thyroid hormones • Diffuse through plasma membrane • Enter nucleus • Forms “hormone-receptor complex” • H-R complex binds to chromosome to activate/inactivate gene(s) Endocrine-System.ppt
Mechanisms of Hormone Action • Peptides & water-soluble amines • Hormone (A) binds to receptor on cell surface • Activates G- protein • Activates adenylate cyclase • Converts ATP to cAMP • cAMP activates protein kinases, which produce final effect. Endocrine-System.ppt
Mechanisms of Hormone Action • Peptides & water-soluble amines • Other Hormone (B) binds to receptor on cell surface • Activates G- protein • Inhibits adenylate cyclase • Stops ATP to cAMP • inhibits final effect of first hormone Endocrine-System.ppt