Chapter 45: Endocrine System and Hormones


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Chapter 45: Endocrine System and Hormones

  1. 1. Endocrine System HormonesAP Biology 2007-2008
  2. 2. 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 growth hormones  maturation AP Biologyreproduction
  3. 3. 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 responseAP Biology
  4. 4. Regulation by chemical messengers  Neurotransmitters released by neurons  Hormones release by endocrine glands endocrine gland neurotransmitter axon hormone carried by bloodreceptor proteins receptor proteins Lock & Key AP Biology system target cell
  5. 5. Classes of Hormones  Protein-based hormones  polypeptides  small proteins: insulin, ADH insulin  glycoproteins  large proteins + carbohydrate: FSH, LH  amines  modified amino acids: epinephrine, melatonin  Lipid-based hormones  steroids  modified cholesterol: sex hormones, aldosteroneAP Biology
  6. 6. 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 responseAP Biology  enzyme action, uptake or secretion of molecules…
  7. 7. Action of lipid (steroid) hormones target cell steroid hormone blood S 1 S cross cell membrane protein S carrier cytoplasm 2 binds to receptor proteinbecomestranscription factor 5 mRNA read by ribosome 3 S plasma membraneDNA 4 mRNA 6 7 nucleus protein protein secreted AP Biologysecreted protein = growth factor (hair, bone, muscle, gametes) ex:
  8. 8. signal-transduction pathway Action of protein hormones 1 signalprotein P plasma membranehormonebinds to receptor protein activates G-protein activates enzyme receptor cAM acts as 2° messenger protein P activates ATP ATP transduction GTP cytoplasmic activates 2 signal enzyme secondary cytoplasm activates messenger enzyme system targetAP Biology cell produces an action 3 response
  9. 9. Ex: Action of epinephrine (adrenaline)signal adrenal gland 1 epinephrine activates 3 G protein activatesreceptor adenylyl cyclaseproteinin cell GDP cAMPmembrane 4 transduction 2 ATP activates GTP protein kinase-A 5 activates GTP activates phosphorylase kinase cytoplasm activates released glycogen phosphorylase to blood 7 glycogen 6 glucose liver cellAP Biology response
  10. 10. Benefits of a 2° messenger system signal 1 Activated adenylyl cyclasereceptor protein Not yet 2 amplification activated 4 amplification 3 cAMP amplification 5 GTP G protein protein kinase 6 amplificationAmplification! enzymeCascade multiplier! 7 amplificationFAST response! AP Biology product
  11. 11. Maintaining homeostasis hormone 1 gland lowers body condition high specific body condition low raises gland body condition Negative FeedbackAP Biology hormone 2 Model
  12. 12. Nervous System Control Feedback Controlling Body Temperature nerve signals hypothalamus sweat dilates surface blood vessels high body temperature (37°C) low hypothalamusconstricts surface shiver blood vessels AP Biology nerve signals
  13. 13. Endocrine System Control Feedback Regulation of Blood Sugar islets of Langerhans insulin beta islet cells body liver stores reduces cells take glycogen appetite pancreas up sugar from blood liver high blood sugar level (90mg/100ml) low liver triggers releases hunger glucose pancreas islets of Langerhans AP Biology liver glucagon alpha islet cells
  14. 14. Endocrine System Control Feedback Blood Osmolarity osmoreceptors in ADH hypothalamus increased increase water thirst pituitary reabsorption high nephron blood osmolarity JuxtaGlomerular blood pressure Apparatus nephron low increasedadrenal water & salt nephron gland reabsorption (JGA) renin aldosterone angiotensinogen AP Biology angiotensin
  15. 15. 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 hypothalamus  secretes broad range of “tropic” hormones posterior regulating other glands in body pituitary anteriorAP Biology
  16. 16. tropic hormones = target endocrine glands hypothalamus thyroid-stimulating hormone posterior antidiuretic (TSH) pituitary hormone Thyroid gland (ADH) anterior pituitary Kidney tubules Muscles of uterus gonadotropic hormones: Adrenal follicle- cortex stimulating hormone (FSH) & luteinizing hormone (LH) Melanocyte in amphibian Bone Mammary and muscle glands Testes Ovaries in mammalsAP Biology
  17. 17. Homology in hormones What does this tell you about these hormones? How could these hormones have different effects? same gene family prolactin growth gene duplication? hormone mammals birds fish amphibians milk fat salt & metamorphosis growthproduction metabolism water & maturation & development balanceAP Biology
  18. 18. 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 tyrosine  reproduction + iodineAP Biology thyroxines
  19. 19. Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine +tyrosine ✗ + iodineAP Biology ✗ thyroxines
  20. 20. Endocrine System Control Feedback Regulation of Blood Calcium calcitonin  kidney thyroid reabsorption Ca++ deposited of Ca++ in bones high blood calcium level (10 mg/100mL)  Ca++ uptake in intestines low activated Vitamin D  kidney parathyroid bones reabsorptionrelease Ca++ of Ca++AP Biology parathyroid hormone (PTH)
  21. 21. Feedback Female reproductive cycle egg builds up estrogen matures & uterus lining is released (ovulation) corpusovary luteum progesterone FSH & LH fertilized egg maintains (zygote)pituitary uterus lining hCG gland yes corpus luteum pregnancy GnRH no progesterone corpus luteum breaks down hypothalamus progesterone drops maintains AP Biology menstruation uterus lining
  22. 22. AP Biology
  23. 23. Any Questions?? Robert Wadlow 1918-1940 8 11"AP Biology 2009-2010
  24. 24. Effects of stress on a body Stress Nerve Hypothalamus Spinal cord signals (cross section) Releasing hormone Nerve cell Anterior pituitary Blood vessel adrenal medulla Nerve cellsecretes epinephrine Adrenal cortex & norepinephrine secretes ACTH mineralocorticoids & glucocorticoids Adrenal gland Kidney (A) SHORT-TERM STRESS RESPONSE (B) LONG-TERM STRESS RESPONSE Effects of epinephrine and norepinephrine: Effects of Effects of mineralocorticoids: glucocorticoids: 1. Glycogen broken down to glucose; increased blood glucose 1. Retention of 1. Proteins & fats broken 2. Increased blood pressure sodium ions & down & converted to 3. Increased breathing rate water by kidneys glucose, leading to 4. Increased metabolic rate increased blood 2. Increased blood 5. Change in blood flow patterns, leading glucose volume & blood to increased alertness & decreased pressure 2. Immune system AP Biology digestive & kidney activity suppressed