Chapter 45 Endocrine System

Ch. 40 Review 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. 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 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 pheromones 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

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 response enzyme action, uptake or secretion of molecules…

Action of lipid (steroid) hormones target cell blood S 1 S cross cell membrane protein carrier S 2 cytoplasm binds to receptor protein becomes transcription factor 5 mRNA read by ribosome 3 S plasma membrane 4 DNA mRNA 6 7 nucleus protein protein secreted ex: secreted protein = growth factor (hair, bone, muscle, gametes)

Action of protein hormones signal-transduction pathway Action of protein hormones 1 signal protein hormone P plasma membrane binds to receptor protein activates G-protein activates enzyme cAMP receptor protein acts as 2° messenger ATP transduction GTP activates cytoplasmic signal transduction: the action or process of converting something and especially energy or a message into another form ATP activates enzyme 2 secondary messenger system cytoplasm activates enzyme 3 response target cell produces an action

cAMP cAMP = cyclic adenosine monophosphate GPCR  adenylyl cyclase (convert ATP  cAMP)  activate protein kinase A

Ex: Action of epinephrine (adrenaline) adrenal gland signal 1 epinephrine activates G protein 3 activates adenylyl cyclase receptor protein in cell membrane GDP cAMP transduction 4 ATP 2 GTP activates protein kinase-A 5 activates GTP activates phosphorylase kinase cytoplasm released to blood activates glycogen phosphorylase 7 liver cell glycogen 6 glucose response

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 Tropic- hormone affects another endocrine gland; Non-tropic- has direct target

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.