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Biology 201 Dr. Edwin DeMont

Biology 201 Dr. Edwin DeMont. The Endocrine System and Chemical Messengers. St. Francis Xavier University. Communication systems. Two forms of communication integrate body function that helps to maintain homeostasis:.

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Biology 201 Dr. Edwin DeMont

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  1. Biology 201Dr. Edwin DeMont The Endocrine System and Chemical Messengers St. Francis Xavier University

  2. Communication systems Two forms of communication integrate body function that helps to maintain homeostasis: (1) Neurons which transmit electrical signals to initiate a rapid response in a tissue. (2) Hormones which are a slower chemical signals that initiate a widespread and often prolonged response and often in a variety of tissues. Biology 404 - Comparative Endocrinology St. Francis Xavier University

  3. Endocrine System The endocrine system uses chemical messengers in the coordination of growth, maturation, and reproduction. Endocrine glands secrete their products (hormones) into the circulatory system There are many mammalian endocrine organs. St. Francis Xavier University

  4. Endocrine System Most hormones are proteins, amines, or steroids. They are effective in very small amounts. Hormones act by: (1) increasing transport rates of a cell, (2) stimulating a cell to increase rates of chemical synthesis, or (3) causing the target cell to activate or suppress enzymes. St. Francis Xavier University

  5. Fixed-Membrane-Receptor Protein or amine hormones These hormones bind to receptors in the plasma membrane of target cells. Upon binding to the receptor, ATP is converted into cyclic AMP that acts as the “second messenger.” St. Francis Xavier University

  6. Mobile-Receptor Steroid hormones. The hormones readily pass through the plasma membrane by diffusion, and bind to receptors in the cytoplasm of target cells. This protein-hormone association diffuses into the nucleus of the cell and binds to DNA in order to regulate its activity. DNA in target cells, in turn, regulates mRNA, which exits the nucleus and moves to the RER where protein synthesis takes place. St. Francis Xavier University

  7. Hormonal Feedback The parathyroid secretes PTH, which regulates calcium and phosphate levels in the blood. PTH stimulates release of calcium and phosphate from the skeletal system into the bloodstream. St. Francis Xavier University

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