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April 4, 2011

April 4, 2011. BR: Review- how are chemical signals in the body transmitted from cell to cell? Obj : Explain how hormones exert an action on our cells HW: Study, study, study for unit Exam- chps 40-49. Endocrine System Hormones. Regulation. Why are hormones needed?

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April 4, 2011

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  1. April 4, 2011 • BR: Review- how are chemical signals in the body transmitted from cell to cell? • Obj: Explain how hormones exert an action on our cells • HW: Study, study, study for unit Exam-chps 40-49

  2. Endocrine System Hormones

  3. Regulation • Why are hormones needed? • chemical messages from one body part to another • communication needed to coordinate whole body • daily homeostasis & regulation of large scale changes • solute levels in blood • glucose, Ca++, salts, etc. • metabolism • growth • development • maturation • reproduction growth hormones

  4. Regulation & Communication • Animals rely on 2 systems for regulation • endocrine system • system of ductless glands • secrete chemical signals directly into blood • chemical travels to target tissue • target cells have receptor proteins • slow, long-lasting response • nervous system • system of neurons • transmits “electrical” signal & release neurotransmitters 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 Lock & Keysystem target cell

  6. Learning Check • What are the sources of the body’s chemical signals? • Compare and contrast endocrine signals and nerve signals

  7. 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 insulin

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

  9. Action of lipid (steroid) hormones steroid hormone target cell blood S 1 S cross cell membrane protein carrier S 2 cytoplasm binds to receptor protein becomes transcription factor 5 mRNA read by ribosome S 3 plasma membrane 4 DNA mRNA 6 7 nucleus protein protein secreted ex: secreted protein = growth factor (hair, bone, muscle, gametes)

  10. signal-transduction pathway Action of protein hormones 1 signal proteinhormone plasma membrane P activates G-protein binds to receptor protein activates enzyme cAMP acts as 2° messenger receptorprotein ATP transduction GTP activatescytoplasmicsignal ATP activates enzyme 2 secondary messengersystem activates enzyme cytoplasm response 3 produces an action target cell

  11. adrenal gland Ex: Action of epinephrine (adrenaline) signal 1 epinephrine activatesG protein 3 activatesadenylyl cyclase receptor protein in cell membrane cAMP GDP transduction 4 ATP 2 GTP activates protein kinase-A 5 activates GTP activates phosphorylase kinase cytoplasm releasedto blood activates glycogen phosphorylase 7 glycogen glucose 6 liver cell response

  12. Benefits of a 2° messenger system Amplification! 1 signal Activated adenylyl cyclase receptor protein Not yet activated 2 amplification 4 amplification 3 cAMP 5 amplification GTP G protein protein kinase 6 amplification enzyme Cascade multiplier! 7 amplification FAST response! product

  13. high low Maintaining homeostasis hormone 1 lowersbody condition gland specific body condition raisesbody condition gland Negative FeedbackModel hormone 2

  14. hypothalamus hypothalamus high low Nervous System Control Feedback Controlling Body Temperature nerve signals sweat dilates surfaceblood vessels body temperature (37°C) constricts surfaceblood vessels shiver nerve signals

  15. pancreas high liver low pancreas liver Endocrine System Control Feedback Regulation of Blood Sugar islets of Langerhans beta islet cells insulin body cells takeup sugar from blood liver storesglycogen reducesappetite blood sugar level (90mg/100ml) liver releasesglucose triggershunger islets of Langerhansalpha islet cells glucagon

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

  17. Learning Check • Explain the components of a negative feedback loop. • Proved an example of a body function that is regulated through a negative feedback loop

  18. Nervous & Endocrine systems linked • Hypothalamus = “master nerve control center” • nervous system • receives information from nerves around body about internal conditions • releasing hormones: regulates release of hormones from pituitary • Pituitary gland = “master gland” • endocrine system • secretes broad rangeof “tropic” hormones regulating other glands in body hypothalamus posterior pituitary anterior

  19. tropic hormones = target endocrine glands 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 Ovaries Testes

  20. Learning Check • Partner up • Stand up and point to each of the major endocrine glands • Describe what they secrete and the effect of the secretion on the body

  21. same gene family growthhormone birds fish amphibians fatmetabolism salt &waterbalance metamorphosis& maturation growth& development Homology in hormones What does this tell you about these hormones? How could these hormones have different effects? prolactin gene duplication? mammals milkproduction

  22. 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 thyroxines

  23. Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine + ✗ tyrosine + iodine ✗ thyroxines

  24.  kidney reabsorption of Ca++ thyroid Ca++ depositedin bones high  Ca++uptakein intestines low parathyroid  kidney reabsorption of Ca++ bones release Ca++ Endocrine System Control Feedback Regulation of Blood Calcium calcitonin blood calcium level(10 mg/100mL) activated Vitamin D parathyroid hormone (PTH)

  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 pituitarygland hCG pregnancy progesterone GnRH corpus luteum breaks down progesterone drops menstruation hypothalamus maintainsuterus lining

  26. Any Questions?? Robert Wadlow 1918-1940 8' 11"

  27. Effects of stress on a body Stress Nerve signals Hypothalamus Spinal cord (cross section) Releasing hormone Nerve cell Anterior pituitary Blood vessel adrenal medulla secretes epinephrine & norepinephrine Nerve cell Adrenal cortex secretes mineralocorticoids & glucocorticoids ACTH Adrenal gland Kidney CORTEX MEDULLA (A) SHORT-TERM STRESS RESPONSE (B) LONG-TERM STRESS RESPONSE Effects of mineralocorticoids: 1. Retention of sodium ions & water by kidneys 2. Increased blood volume & blood pressure Effects of glucocorticoids: 1. Proteins & fats broken down & converted to glucose, leading to increased blood glucose 2. Immune system suppressed Effects of epinephrine and norepinephrine: 1. Glycogen broken down to glucose; increased blood glucose 2. Increased blood pressure 3. Increased breathing rate 4. Increased metabolic rate 5. Change in blood flow patterns, leading to increased alertness & decreased digestive & kidney activity

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