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Chapter 45: Hormones & the Endocrine System

Chapter 45: Hormones & the Endocrine System. Regulatory systems Nervous system High speed messages Endocrine system Slower; longer lasting Result of hormone secretion Connections between Nervous & endocrine systems Neurosecretory cells Nerve cells that release hormones

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Chapter 45: Hormones & the Endocrine System

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  1. Chapter 45: Hormones & the Endocrine System Regulatory systems Nervous system High speed messages Endocrine system Slower; longer lasting Result of hormone secretion Connections between Nervous & endocrine systems Neurosecretory cells Nerve cells that release hormones Concentrated in hypothalamus Some hormones act as neurotransmitters Ex: epinephrine

  2. Hormones • Chemical signal secreted into circulatory system through ductless glands • Action of hormones • Operate at all levels of organization • Intracellular, cell to cell, organ to organ, organism to organism (pheromones) • Produce developmental change • Ex. puberty • Metamorphosis (insects & amphibians) • Incomplete • Eggnymphadult (grasshoppers) • Complete • Egglarvapupaadult (butterfly)

  3. Regulation of hormones • Negative feedback • Increase in substance inhibits its own production • Ex. Metabolic control • Positive feedback • Increase in substance increases its own production • Ex. Release of milk in nursing mother • Local regulators • Histamines • Chemical from local cell for antigen-antibody response (allergies) • Interleukins • Cytokine acting as communicator between immune cells • Prostaglandins • Modified fatty acid which stimulates contraction of smooth muscles, induces fever & blood flow to infection sites

  4. Classes of molecules acting as hormones • Proteins & peptides; H2O soluble • Amines (derived from amino acids); H2O soluble • Steroids; non- H2O soluble • Events of hormone action • Reception (signal binds to receptor protein in or on target cell) • Water soluble hormones bind to surface receptor triggering activation of internal proteins in transduction pathway • Steroid hormones enter cell & bind to internal receptor which enters nucleus to activate genes • Signal transduction • response

  5. *denotes steroid hormone

  6. Endocrine Disorders • Thyroid • Cretinism • Under secretion of thyroxin in utero • Goiter • Enlarged gland usually related to hypothyroidism • Graves disease • Most common form of hyperthyroidism • Autoimmune • Hashimoto’s disease • Most common form of hypothyroidism • autoimmune • Pituitary • Dwarfism • Under secretion of GH in child • Giantism • Over secretion of GH in child • Acromegaly • Over secretion of GH in adult

  7. Pancreas • Diabetes mellitus • Type I (insulin dependant) • Autoimmune • Beta cells destroyed; little to no insulin production • Type II • Reduced responsiveness of target cells to insulin • Controlled through diet & exercise • Accounts for >90% of diabetes cases • Adrenal gland • Addison’s disease • Under-secretion of ACTH

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