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Ch. 40 Warm-Up

Explore the role of hormones in maintaining homeostasis, regulating body temperature, and controlling blood sugar levels. Understand the different types of hormones and their effects on target organs, as well as how positive and negative feedback mechanisms maintain balance in the body. Discover the functions of key glands and hormones in the endocrine system.

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Ch. 40 Warm-Up

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  1. Ch. 40 Warm-Up • What type of behavior in animals might be triggered by cold temperatures? • What type of behaviors might be triggered in hot temperatures? • List 2 examples of negative feedback. List 2 examples of positive feedback. • What is the main type of chemical messenger in the endocrine system? The nervous system?

  2. Ch. 45 Warm-Up • Compare peptide hormones to steroids. • Explain how insulin and glucagon work to regulate blood sugar levels. • Which glands and hormones respond when your body is under stress?

  3. Chapter 45Hormones and the Endocrine System A hormone called ecdysteroid regulates the timing of metamorphosis in this anise swallowtail butterfly.

  4. You must know: • Two ways hormones affect target organs. • The secretion, target, action, and regulation of at least 3 hormones. • An illustration of both positive and negative feedback in the regulation of homeostasis by hormones.

  5. Hormones • Why are hormones needed? • chemical messages from one body part to cells in other parts of body • communication needed to coordinate whole body • maintaining homeostasis • energy production • growth • development • maturation • reproduction growth hormones

  6. Endocrine System • Endocrine system releases hormones • glands which secrete chemical signals into blood • chemicals cause changes in other parts of body • slow, long-lasting response • growth hormones • sex hormones • response hormones • metabolism hormones • and more….

  7. Types of Intercellular Signaling

  8. Endocrine System= Hormone-secreting cells + Tissues • Endocrine glands: ductless, secrete hormones directly into body fluids • Hormones: chemical signals that cause a response in target cells (receptor proteins for specific hormones) • Affects 1 tissue, a few, or most tissues in body • Or affect other endocrine glands (tropic hormones) • Regulation by Positive & Negative Feedback

  9. Glands • Pineal • melatonin • Pituitary • many hormones: master gland • Thyroid • thyroxine • Adrenal • adrenaline • Pancreas • insulin, glucagon • Ovary • estrogen • Testes • testosterone

  10. Discovery Video: Endocrine System

  11. Types of Hormones Peptide Steroid Lipid-soluble Enters cell & binds to intracellularreceptors Causes change in gene expression (protein synthesis) Slower response Longer life Eg. androgens (testosterone), estrogen, progesterone, cortisol • Water-soluble • Bind to receptors on plasma membrane& triggers signal transduction pathway • Affects protein activity already present in cell • Rapid response • Short-lived • Eg. oxytocin, insulin, epinephrine

  12. high low Maintaining homeostasis hormone 1 lowersbody condition gland specific body condition raisesbody condition gland hormone 2

  13. high Negative Feedback • Response to changed body condition • every time body is high or low from normal level a signal tells the body to make changes that will bring body back to normal level • once body is back to normal level, signal is turned off hormone 1 lowersbody condition gland specific body condition

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

  15. Endocrine System Control pancreas high liver low pancreas liver Regulation of Blood Sugar insulin body cells takeup sugar from blood liver storessugar reducesappetite blood sugar level (90mg/100ml) liver releasessugar triggershunger glucagon

  16. Negative feedback systems: • Thyroid hormones • Blood Ca2+ levels • Blood glucose levels • Positive feedback system: • Oxytocin (birthing process; release of milk/suckling)

  17. Epinephrine: one hormone  many effects • Liver cells break down glycogen and release glucose • Blood vessels to skeletal muscles dilate • Blood vessels to intestines constrict

  18. Master Glands Hypothalamus Pituitary Gland

  19. Master Glands • Receives info from nerves and brain • Initiates endocrine signals Hypothalamus Posterior pituitary gland: • Oxytocin: contract uterine muscles, eject milk in nursing • Antidiuretic Hormone (ADH): promote H2O retention by kidneys Pituitary Gland Anterior pituitary gland: • Follicle-stimulating hormone (FSH): development of ovarian follicles (eggs); promote sperm production • Luteinizing hormone (LH): trigger ovulation; stimulate testosterone production in testes

  20. BIOFLIX: HOMEOSTASIS – BLOOD SUGAR

  21. High blood glucose Control of Blood Glucose Body cells take up glucose Liver stores glucose as glycogen Insulinreleased from pancreas Liver breaks down glycogen and releases glucose into blood Blood glucose drops Glucagonreleased from pancreas

  22. Diabetes Mellitus • Type I diabetes (10%):deficiency of insulin • Insulin-dependent • Autoimmune disorder  beta cells of pancreas destroyed • Type II diabetes (90%): failure of target cells to respond to insulin • Non-insulin dependent • Insulin produced  cells don’t respond (defect in insulin receptor or response pathway) • Risk factors: obesity, lack of exercise

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