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HORMONE PRODUCTION AND STORAGE

HORMONE PRODUCTION AND STORAGE. DR AMNA TAHR ASSISTANT PROFESSOR PHYSIOLOGY DEPARTMENT KEMU. HORMONE.

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HORMONE PRODUCTION AND STORAGE

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  1. HORMONE PRODUCTION AND STORAGE DR AMNA TAHR ASSISTANT PROFESSOR PHYSIOLOGY DEPARTMENT KEMU

  2. HORMONE • A  hormone  is a chemical substance produced in particular parts of organisms by specific cells, glands, and/or tissues and then transported to other parts of the body, with the intent of influencing a variety of physiological and behavioral activities, such as the processes of digestion, metabolism, growth,reproduction and mood control. 

  3. ENDOCRINE SYSTEM • The endocrine systemis a ductless system referring to the collection of cells, glands, and tissues of an organism that secretehormones directly into the bloodstream to control the organisms' physiological and behavioral activities. • The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. • The word endocrine derives from the Greek words "endo" meaning inside, within, and "crinis" for secrete.

  4. ENDOCRINE ORGANS

  5. MAJOR CLASSES OF HORMONES 1- Proteinandpeptides including hormones secreted by anterior and posterior pituitary, the pancreas , parathyroid gland 2- Steroids secreted by the adrenal cortex, the ovaries, testes 3- Derivativeoftheaminoacidtyrosine, secreted by thyroid gland , adrenal medullae.

  6. HORMONE PRODUCTION AND STORAGE • Polypeptide and protein hormone are stored in secretory vesicles until needed. • Steroid hormones are usually synthesized from cholesterol and not stored. • Amine hormones are derived from tyrosine

  7. FEED BACK CONTROL OF HORMONE SECRETION • Negative feedback mechanism • Is most commonly applied principle for regulating hormone secretion • It prevents over activity of the hormone system • Is self -limiting • A hormone has biologic actions that, directly or indirectly , inhibit further secretion of the hormone

  8. FEED BACK CONTROL OF HORMONE SECRETION • Positive feedback mechanism • is rare • Is explosive and self – reinforcing • Surges of hormone can occur with positive feed back • A hormone has biologic actions that, directly or indirectly, cause more secretion of the hormone

  9. MECHANISM OF ACTION OF HORMONE • Hormone receptors and their activation • Location of receptors for different hormones • In or on the surface of cell membrane for protein , peptide and catecholamine hormones • In the cell cytoplasm for steroid hormones • In the cell nucleus for thyroid hormones

  10. INTRACELLULAR SIGNALING AFTER HORMONE RECEPTOR ACTIVATION • Ion Channel –linked receptors • G-Protein-linked Hormone receptors • Enzyme-linked hormone receptors

  11. Ion Channel –linked receptors

  12. G-Protein-linked Hormone receptors

  13. Enzyme-linked hormone receptors

  14. SECOND MESSANGER MECHANISM • AdenylCyclase – cAMP second messenger system • Cell Membrane Phospholipid second messenger system • Calcium -Calmodulin second messenger system

  15. AdenylCyclase – cAMP second messenger system

  16. Cell Membrane Phospholipid second messenger system

  17. Mechanism of interaction of lipophilic hormones

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