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Endocrine System Hormones

Endocrine System Hormones. Regulation. Why are hormones needed? chemical messages from one body part to another communication needed to coordinate whole body homeostasis & regulation metabolism growth development maturation reproduction. growth hormones.

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Endocrine System Hormones

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  1. Endocrine System Hormones

  2. Regulation • Why are hormones needed? • chemical messages from one body part to another • communication needed to coordinate whole body • homeostasis & regulation • metabolism • growth • development • maturation • reproduction growth hormones

  3. Types of Hormonal Communication • Autocrine- cell signals to itself • Paracrine- cell signals to neighbor cell • Endocrine- cell signal carried in the blood stream • Exocrine- cell signal carried in ducts

  4. Regulation & Communication • Animals rely on 2 systems for regulation • endocrine system • ductless gland which secrete chemical signals directly into blood • chemical travels to target tissue • slow, long-lasting response • nervous system • system of neurons, central nerve system • transmits “electrical” signal to target tissue • fast, short-lasting response

  5. Regulation by chemical messengers • Neurotransmitters released by neurons • Hormones release by endocrine glands Endocrine gland Neurotransmitter Axon Hormone carried by blood Receptor proteins Receptor proteins Target cell

  6. Classes of Hormones • Protein-based hormones • polypeptides • small proteins: insulin, ADH • glycoproteins • large proteins + carbohydrate: FSH, LH • amines • modified amino acids: epinephrine, melatonin • Lipid-based hormones • steroids • modified cholesterol: sex hormones, aldosterone

  7. How do hormones act on target cells • Lipid-based hormones • hydrophobic & lipid-soluble • diffuse across membrane & enter cells • bind to receptor proteins in cytoplasm & nucleus • bind to DNA as transcription factors • Protein-based hormones • hydrophilic & not lipid soluble • can’t diffuse across membrane • trigger secondary messenger pathway • activate cellular response • enzyme action, uptake or secretion of molecules…

  8. Action of lipid (steroid) hormones cytoplasm steroid hormone blood S S 1 protein carrier S 2 receptor protein 4 S 3 DNA 5 mRNA plasma membrane protein nucleus

  9. Action of protein hormones 1 Protein hormone activatesenzyme G protein cAMP Receptor protein 3 2 ATP protein messengercascade activates enzyme GTP activates enzyme 4 cytoplasm Produces an action

  10. Action of epinephrine (adrenalin) liver cell 1 epinephrine activatesadenylyl cyclase adrenal gland G protein cAMP 3 receptor protein 2 ATP activates protein kinase-A GTP releasedto blood activates phosphorylase 4 cytoplasm glycogen glucose

  11. Benefits of a 2° messenger system Amplification! 1 Receptor protein Activated adenylyl cyclase Signal molecule Not yet activated Amplification 2 4 Amplification cAMP 3 5 GTP G protein Protein kinase 6 Amplification Enzyme Amplification 7 Enzymatic product

  12. Organs of the Endocrine System

  13. high low Negative Feedback Model hormone 1 lowersbody condition gland specific body condition raisesbody condition gland hormone 2

  14. high low Nervous System Control Feedback Body Temperature nerve signals brain sweat dilates surfaceblood vessels body temperature brain constricts surfaceblood vessels shiver nerve signals

  15. pancreas high liver low pancreas liver Endocrine System Control Feedback Blood Sugar insulin body cells takeup sugar from blood liver storessugar reducesappetite blood sugar level liver releasessugar triggershunger glucagon

  16. increasethirst pituitary nephron high low adrenalgland nephron Endocrine System Control Feedback Blood Osmolarity ADH increasedwaterreabsorption blood osmolarity blood pressure increasedwater & saltreabsorption renin aldosterone angiotensinogen angiotensin

  17. Endocrine & Nervous system links • Hypothalamus = “master control center” • nervous system • receives information from nerves around body about internal conditions • regulates release of hormones from pituitary • Pituitary gland = “master gland” • endocrine system • secretes broad rangeof hormones regulating other glands

  18. The Pituitary Gland • Particulars • Size: about the size of a pea and weighing 0.5 g • Location:protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) • Anterior Pituitary • From glandular tissue - synthesizes its own products • Posterior Pituitary • projection of tissue from the hypothalamus - stores hypothalamic products

  19. Hypothalamus Thyroid-stimulating Hormone (TSH) Antidiuretic hormone (ADH) Posterior pituitary Thyroid gland Anterior pituitary Kidney tubules Adrenocorticotropic hormone (ACTH) Oxytocin Muscles of uterus Gonadotropic hormones: Follicle- stimulating hormone (FSH) & luteinizing hormone (LH) Melanocyte-stimulating hormone (MSH) Growth hormone (GH) Prolactin (PRL) Adrenal cortex Melanocyte in amphibian Mammary glands in mammals Bone and muscle Ovary Testis

  20. Hypothalamus-Pituitary Axis Nature Reviews Cancer4, 285-295 (April 2004)

  21. Regulating metabolism • Hypothalamus • TRH = TSH-releasing hormone • Anterior Pituitary • TSH = thyroid stimulating hormone • Thyroid • produces thyroxine hormones • metabolism & development • bone growth • mental development • metabolic use of energy • blood pressure & heart rate • muscle tone • digestion • reproduction tyrosine iodine thyroxine

  22. Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine

  23. Regulating blood calcium levels Thyroid Parathyroids Low blood Ca++ – Parathyroid hormone (PTH) Negative feedback Increased absorption of Ca++ from intestine due to PTH activation of Vitamin D Reabsorption of Ca++ & excretion of PO4 Osteoclasts dissolve CaPO4 crystals in bone, releasing Ca++ Increased blood Ca++

  24. Regulating Growth • Hypothalamus • SRIF = somatropin-releasing inhibitory factor • GHRH = growth hormone releasing hormone • Anterior Pituitary • GH = growth hormone • Liver • produces IGF-1=insulin-like growth factor-1 • Effects of IGF-1 • Promotes RNA, DNA and protein synthesis • Cell and tissue growth

  25. corpusluteum ovary yes corpusluteum no Feedback Female reproductive cycle eggmatures & is released(ovulation) builds up uterus lining estrogen progesterone FSH & LH fertilized egg(zygote) maintainsuterus lining HCG pituitarygland pregnancy progesterone GnRH corpus luteum breaks down progesterone drops menstruation maintainsuterus lining hypothalamus

  26. Any Questions??

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