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Endocrine System

Endocrine System. Chapter 13. Endocrine System. Releases hormones Into bloodstream that are then delivered to cells Works with the nervous system Nervous system can stimulate or inhibit hormone release Hormones can promote or inhibit nerve impulses

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Endocrine System

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  1. Endocrine System Chapter 13

  2. Endocrine System • Releases hormones • Into bloodstream that are then delivered to cells • Works with the nervous system • Nervous system can stimulate or inhibit hormone release • Hormones can promote or inhibit nerve impulses • http://www.unitedstreaming.com/search/assetDetail.cfm?guidAssetID=7230B4F0-E36D-4C81-8E3D-38F6AE6173AE

  3. Two Types of Glands • Exocrine glands – secrete hormones into ducts • Sweat, digestive, mucous, and oil glands • Endocrine glands – secrete hormones into interstitial fluid • Pituitary, thyroid, parathyroid, adrenal, and pineal glands

  4. Functions of Hormones • Regulate body function • Metabolism, energy balance, immune system • Control growth and development • Govern operation of reproductive systems

  5. Hormones • Circulating hormones = pass from the cells that make them into interstitial fluid • Inactivated by liver and excreted by kidneys • Only affects target cells • Binds to particular receptors that are only found on the specific target cells • Local hormones = act on neighboring cells or same cell that made it • Do not enter bloodstream

  6. Lipid Soluble Hormones • Steroid hormones • Thyroid hormones • Nitric oxide

  7. Water Soluble Hormones • Amine hormones • Peptide and protein hormones • Eicosanoid hormones

  8. Control of Hormone Secretion • Signals from nervous system • Chemical changes in blood • Other hormones

  9. Hypothalamus • “master” of pituitary gland • Major connection between endocrine and nervous system • Makes atleast 9 hormones • Neurosecretory cells- release hormones into the bloodstream

  10. Anterior Pituitary Hormones • Human growth hormone (hGH)- cells secrete insulinlike growth factors (IGFs) • Cause cells to grow and multiply • Increase protein synthesis rate • Controlled by GHRH and GHIH • Thyroid-stimulating hormone (TSH)- stimulates thyroid to produce and secrete T3 and T4

  11. Anterior Pituitary Hormones (cont.) 3. Follicle-stimulating hormone (FSH): • Initiates the development of follicles • Stimulates secretion of estrogen from follicular cells • Stimulates sperm production • Estrogen and testosterone inhibit FSH release 4. Luteinizing hormone (LH): • Triggers ovulation • Stimulates estrogen and progesterone secretion • Secretes testosterone

  12. Anterior Pituitary Hormones (cont.) 5. Prolactin (PRL)- initiates milk secretion from mammary glands • Regulated by PIH and PRH 6. Adrenocorticotropic hormone (ACTH)- controls production and secretion of glucocorticoids

  13. Posterior Pituitary Hormones • Tropic hormones = influence other endocrine glands • Does not synthesize hormones • Oxytocin (OT): • Enhances contraction of muscle cells in uterus wall • Stimulates milk ejection

  14. Posterior Pituitary Hormones (cont.) 2. Antidiuretic hormone (ADH): • Kidneys to return more water to the blood • Decrease water loss through sweat • Constriction of arterioles • Increases blood pressure • Other name: vasopressin

  15. Thyroid Gland • Just below the larynx • Right and left lobes connected by isthmus • Two hormones: thyroxine (T4) and triiodothyronine (T3) • Calcitonin (CT)

  16. T3 and T4 • Regulate basal metabolic rate and oxygen use • Regulate cellular metabolism • Regulate growth and development • Regulated by blood iodine level, TRH, and TSH

  17. Calcitonin (CT) • Decreases level of calcium in blood • Unclear importance: can have lots or be absent and no clinical symptoms

  18. Parathyroid Gland • Four small, round masses of tissue • Principal cells- secrete parathyroid hormone (PTH) • PTH: • Regulates calcium, magnesium, and phosphate ions in the blood • Increases osteclasts • Promotes formation of calcitriol • Blood calcium level regulates PTH secretion

  19. Adrenal Glands • Located on top of the kidneys • Adrenal cortex on the outside • Adrenal medulla is the middle of the adrenal gland

  20. Adrenal Cortex Hormones • Mineralocorticoids: control homeostasis of water, sodium ions, and potassium ions • Most influential hormone: aldosterone • Glucocorticoids: protein breakdown, glucose formation, lipolysis, resistance to stress, anti-inflammatory effects, and depresssion of immune response • Most popular: cortisol

  21. Adrenal Cortex Hormones (cont.) 3. Androgens: • Males: secrete small amounts • Females: contribute to sex drive and converted to estrogens • Stimulate growth of axillary and pubic hair and contribute to prepubertal growth spurt

  22. Adrenal Medulla Hormones • Sympathetic postganglionic cells of the autonomic nervous system • Epinephrine (adrenaline) • Norepinephrine (NE) (noradrenaline) • Increase blood pressure, increase blood flow, dilate airways to the lungs, increase glucose and fatty acid blood levels

  23. Pancreas • Located in the curve of the duodenum • Pancreatic islets (islets of Langerhans) contain: • Alpha cells- secrete glucagon • Beta cells- secrete insulin • Delta cells- secrete somatostatin • F cells- secrete pancreatic polypeptide

  24. Glucagon • Increase blood glucose level by: • Accelerating conversion of glycogen into glucose • Promoting conversion of amino acids and lactic acid into glucose • Stimulating the release of glucose into the blood

  25. Insulin • Accelerates diffusion of glucose into body cells • Accelerates conversion of glucose into glycogen and fatty acids • Promotes amino acid uptake into body cells • Slows conversion of glycogen to glucose • Slows glucose formation by liver cells

  26. Ovaries • Produce estrogens and progesterone: • Regulate the menstrual cycle, maintain pregnancy, prepare mammary glands for lactation, develop and maintain sex characteristics • Inhibin: inhibits secretion of FSH • Relaxin: helps enlarge birth canal

  27. Testes • Oval glands that lie in scrotum • Produces testosterone: • Regulates sperm production • Stimulates development and maintenance of male characteristics • Produces inhibin: inhibits FSH secretion

  28. Pineal Gland • Small gland • Secretes melatonin: • Sets body’s biological clock • More melatonin released in darkness • Levels are decrease with adulthood

  29. Thymus • Located behind the sternum between the lungs • Hormones: thymosin, thymic humoral factor (THF), thymic factor (TF), and thymopoietin • Promote maturation of T cells • May delay the aging process

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