CHAPTER 45 HORMONES AND ENDOCRINE SYSTEM HORMONES You

CHAPTER 45 HORMONES AND ENDOCRINE SYSTEM

HORMONES • You only need a little bit of the hormone to cause a response (remember how the signal gets amplified! Look back at chapter 11) • Protein-based hormones • Receptor on the plasma membrane (don’t go inside!) • Water-soluble • Lipid-based hormones • Receptor is inside the cell (go inside the cell!)

SIGNALING REVIEW

RECEPTORS

THE MASTER GLAND (PITUITARY) • Under the hypothalamus • Posterior Pituitary • Directly connected to hypothalamus by neurosecretory cells • Only STORES hormones that are produced by the hypothalamus • Anterior Pituitary • Indirectly connected to hypothalamus (still under its control) by capillary portal system • Makes its own hormones and releases them

POSTERIOR PITUITARY • Antidiuretic Hormone (ADH) • Targets kidney tubules • Retention of water • Oxytocin • “Swift birth” • Targets mammary glands, uterine muscles • Let down of milk

ANTERIOR PITUITARY • Adrenocorticotrophic Hormone • Assists in synthesizing corticosteroids, which are responsible for stress response • Thyroid Stimulating Hormone • Regulates body temperature, thirst and hunger • Follicle Stimulating Hormone • Stimulates the maturation of egg and sperm • Luteinizing Hormone • Stimulates secretion of sex steroids from the gonads • Prolactin • Stimulates milk production in breasts • Melanocyte Stimulating Hormone • Regulates the function of skin pigment cells (melanocytes) • Growth Hormone • Growth in bones, tissues, and other body systems

TROPIC VS NONTROPIC • Tropic • Target endocrine glands • Ex. TSH stimulates the thyroid to produce thyroxine • Nontropic • Direct effect on target cells, tissues • Ex. Melanocyte Stimulating Hormone (MSH)- affects skin cells, Prolactin- Affects cells in the mammary glands to make milk, Thyroxine • Both • Ex. Growth hormone – tells bone and tissue cells to grow (nontropic), causes liver to make insulinlike growth factors which tell other cells to grow (tropic)

ISSUES • Acromegaly • Too much Human Growth Hormone • You can see it in the hands, jaw, and brow ridge • Can by caused by a pituitary tumor, which causes the production of too much growth hormone