Ch. 32 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?
Ch. 32 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 32 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 3 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 1 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 1 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. peptide, steroid hormones Eg. cytokines, growth factors, 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: one hormone many effects Liver cells break down glycogen and release glucose Blood vessels to skeletal muscles dilate Blood vessels to intestines constrict
Master Glands Hypothalamus Pituitary Gland
Master Glands Hypothalamus Pituitary Gland 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
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 Liver stores glucose as glycogen Glucagon released from pancreas 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 Graves’ Disease: Autoimmune disorder Hypothalamus TRH Anterior pituitary TSH Thyroid T3 T4 Graves’ Disease: Autoimmune disorder Antibodies bind to TSH receptor Hyperthyroidism High temp, sweating, weight loss, high BP
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, male-pattern 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.