Chapter 45 Hormones and the endocrine system. After studying this chapter you will be able to understand: 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.
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 examples of negative feedback List examples of positive feedback What is the main type of chemical messenger in the endocrine system? The nervous system? 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? Chapter 45 Hormones and the Endocrine System A hormone called ecdysteroid regulates the timing of metamorphosis in this anise swallowtail butterfly You must know: • Two ways hormones affect target organs • The secretion, target, action, and regulation of at least hormones • An illustration of both positive and negative feedback in the regulation of homeostasis by hormones Types of Intercellular Signaling • 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 tissue, a few, or most tissues in body – Or affect other endocrine glands (tropic hormones) • Regulation by Positive & Negative Feedback Pheromones Hormones Local Regulators Chemical signal from individual to another individual Chemical signal from endocrine gland through blood to target cell Chemical signal from one cell to an adjacent cell Eg ant trail; sex phermones Eg cytokines, Eg peptide, growth factors, steroid hormones nitric oxide (NO) Discovery Video: Endocrine System Types of Hormones Peptide Steroid • 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 • Lipid-soluble • Enters cell & binds to intracellular receptors • Causes change in gene expression (protein synthesis) • Slower response • Longer life • Eg androgens (testosterone), estrogen, progesterone, cortisol Epinephrine: Epinephrine one hormone many effects 1.Liver cells break 2.Blood vessels to down glycogen and skeletal muscles release glucose dilate 3.Blood vessels to intestines constrict Master Glands Hypothalamus Pituitary Gland Master Glands Hypothalamus • Receives info from nerves and brain • Initiates endocrine signals Posterior pituitary gland: •Oxytocin: contract uterine muscles, eject milk in nursing Pituitary Gland •Antidiuretic Hormone (ADH): promote H2O retention by kidneys 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 Hypothalamus regulation of Posterior Pituitary gland Hypothalamus regulation of Anterior Pituitary gland Negative feedback systems: • Thyroid hormones • Blood Ca2+ levels • Blood glucose levels Positive feedback system: • Oxytocin (birthing process; release of milk/suckling) BIOFLIX: HOMEOSTASIS – BLOOD SUGAR Control of Blood Glucose High blood glucose Liver breaks down glycogen and releases glucose into blood Insulin released from pancreas Body cells take up glucose Glucagon released from pancreas Liver stores glucose as glycogen Blood glucose drops 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 Thyroid Gland Hypothalamus Graves’ Disease: • Autoimmune disorder • Antibodies bind to TSH receptor • Hyperthyroidism • High temp, sweating, weight loss, high BP TRH Anterior pituitary TSH Thyroid T3 T4 Stress and the Adrenal Gland Anabolic-Androgenic Steroid (AAS) Use • Legally prescribed to treat hormone deficiency, loss of muscle mass (cancer, AIDS) • Used to enhance performance and improve physical appearance Effects of AAS Abuse Source: www.drugabuse.gov/infofacts/steroids.html • • • • • • • aggression extreme mood swings liver damage jaundice fluid retention high blood pressure increases in LDL (“bad” cholesterol) • decreases in HDL (“good” cholesterol) • renal failure • severe acne • For men—shrinking of the testicles, reduced sperm count, infertility, baldness, development of breasts, increased risk for prostate cancer • For women—growth of facial hair, malepattern baldness, changes in or cessation of the menstrual cycle, enlargement of the clitoris, deepened voice • For adolescents—stunted growth due to premature skeletal maturation and accelerated puberty changes; risk of not reaching expected height if AAS is taken before the typical adolescent growth spurt • In addition, people who inject AAS run the added risk of contracting or transmitting HIV/AIDS or hepatitis ...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? Chapter. .. stress? Chapter 45 Hormones and the Endocrine System A hormone called ecdysteroid regulates the timing of metamorphosis in this anise swallowtail butterfly You must know: • Two ways hormones affect... target organs • The secretion, target, action, and regulation of at least hormones • An illustration of both positive and negative feedback in the regulation of homeostasis by hormones Types