2. Chapter 41 Chemical Regulation

3. 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

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  slow, long-lasting response  nervous system  system of neurons  transmits “electrical” signal & release neurotransmitters to target tissue  fast, short-lasting response

5. Regulation by Chemicals axon endocrine gland receptor proteins target cell  Neurotransmitters released by neurons  Hormones release by endocrine glands receptor proteins hormone carried by blood neurotransmitter

6. Homology in Hormones prolactin mammals milk production birds fat metabolism amphibians metamorphosis & maturation fish salt & water balance growth & development What does this tell you about these hormones? growth hormone How could this hormone have different effects?

7. Types of Hormones  circulating hormones  hormones that diffuse into the blood to activate target cells far away  local hormones  hormones that affect target cells close to their release site  autocrine: hormone- releasing cell affected  paracrine: hormone affects nearby cells only

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

9. 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  receptor proteins in cell membrane  trigger secondary messenger pathway  activate internal cellular response  enzyme action, uptake or secretion of molecules…

10. nucleus target cell plasma membrane DNA mRNA blood protein carrier S S S S Action of Lipid (Steroid) Hormones receptor protein receptor protein cytoplasm transcription factor ex: growth factors (hair, bone, muscle, gametes) 1 2 3 4 5 steroid hormone protein

11. Signal Transduction Pathway  signal triggers receptor  receptor triggers internal cellular messengers & then cellular response o receptor o signal pathway (2° messengers) o response What kinds of molecules are the receptors?

12. Action of Protein Hormones activates enzyme activates enzyme activates ion channel or enzyme protein hormone ATP produces an action transduction P 1 2 3 cytoplasm receptor protein response signal secondary messenger system signal transduction pathway 2° messenger target cell plasma membrane

13. Benefits of a 2° Messenger System Amplification! signal receptor protein Activated adenylyl cyclase amplification GTPG protein product enzyme protein kinase cAMP Not yet activated 1 2 4 3 5 6 7 POWERFUL response from a small stimulus! amplification

14. adrenal gland Action of Epinephrine (adrenalin) activates protein kinase-A activates protein kinase-A activates glycogen phosphorylase activates glycogen phosphorylase activates adenylyl cyclase epinephrine liver cell released to blood 1 2 4 receptor protein receptor protein cytoplasm 5 glycogen activates phosphorylase kinase activates phosphorylase kinase GTP cAMP 3 activates G protein GDP ATP 6 glucose

15. Nervous & Endocrine Systems Linked  Hypothalamus = “master nerve 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 range of hormones regulating other glands hypothalamus pituitary posterior anterior

16. Thyroid gland hypothalamus anterior pituitary anterior pituitary gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) Mammary glands in mammals Muscles of uterus Kidney tubules posterior pituitary posterior pituitary thyroid-stimulating hormone (TSH) antidiuretic hormone (ADH) Adrenal cortex Bone and muscle Testis Ovary Melanocyte in amphibian adrenocorticotropic hormone (ACTH) melanocyte-stimulating hormone (MSH) oxytocin prolactin (PRL) growth hormone (GH) tropic hormones

17. 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

18.  Mammals regulate use & storage of glucose  insulin reduces blood glucose levels  glucose levels rise above set point, pancreas secretes insulin  promotes transport of glucose into cells & storage of glucose (as glycogen) in liver & muscle cells  drops blood glucose levels  glucagon increases blood glucose levels  when glucose levels drop below set point, pancreas secretes glucagon  promotes breakdown of glycogen & release of glucose into the blood  raises blood glucose levels Managing Glucose Levels

19. liver pancreas liver Regulation of Blood Sugar blood sugar level (90mg/100ml) insulin glucagon pancreas high low Feedback Endocrine System Control islets of Langerhans beta islet cells islets of Langerhans alpha islet cells body cells take up sugar from blood liver stores glycogen reduces appetite liver releases glucose triggers hunger

20. Feedback corpus luteum ovary Female Reproductive Cycle pregnancy maintains uterus lining yes estrogen egg matures & is released (ovulation) egg matures & is released (ovulation) builds up uterus lining FSH & LH progesterone fertilized egg (zygote) hCG corpus luteum breaks down progesterone drops menstruation corpus luteum breaks down progesterone drops menstruation corpus luteum maintains uterus lining GnRH pituitary gland hypothalamus Endocrine System Control no

21. Regulation of Blood Volume / Pressure  Hormone regulation  ADH (antidiuretic hormone)  from pituitary  causes kidneys to reabsorb more water  aldosterone  from adrenal gland  causes kidneys to reabsorb Na +  atrial natriuretic hormone  from heart (right atrium)  promotes excretion of Na + in urine  nitric oxide  from blood vessel cells  dilates blood vessels  nitroglycerin & Viagra release nitric oxide  BP   

22. Phototropism  Growth towards light Went 1926

23. Phytochrome Photoreceptors  Molecular switch reaction to red light  conversion of P r  P fr in sunlight stimulates germination, flowering, branching…  conversion of P fr  P r in dark inhibits response, & stimulates other responses: growth in height Light induced Phytochrome Chromophore Photoreceptor Kinase activity Response: Vertical growth Phytochrome

24. Flowering Response Short-day plantsLong-day plants  Triggered by photoperiod  relative lengths of day & night  night length—“critical period”— is trigger Plant is sensitive to red light exposure! What is the evolutionary advantage of photoperiodism? Synchronizes plant responses to season!

25. Signal Transduction Pathway 1. Light signal is detected by the phytochrome receptor, which then activates at least 2 signal transduction pathways 2. One pathway uses cGMP as a 2nd messenger to activate a protein kinase. The other pathway involves increases in cytoplasmic Ca 2+ that activates a different protein kinase. 3. Both pathways lead to expression of genes for proteins that function in greening response of plant.