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Endocrine System Hormones AP Biology 2007-2008 Regulation § Why are hormones needed? chemical messages from one body part to another u communication needed to coordinate whole body u daily homeostasis & regulation of large scale changes u § solute levels in blood w glucose, Ca++, salts, etc. § metabolism § growth § development § maturation AP Biology § reproduction growth hormones Regulation & Communication § Animals rely on 2 systems for regulation u endocrine system § system of ductless glands w secrete chemical signals directly into blood w chemical travels to target tissue w target cells have receptor proteins w slow, long-lasting response u nervous system § system of neurons w transmits “electrical” signal & release neurotransmitters to target tissue w fast, short-lasting response AP Biology Regulation by chemical messengers § Neurotransmitters released by neurons § Hormones release by endocrine glands endocrine gland neurotransmitter axon hormone carried by blood receptor proteins AP Biology receptor proteins target cell Lock & Key system Classes of Hormones § Protein-based hormones u polypeptides § small proteins: insulin, ADH u insulin glycoproteins § large proteins + carbohydrate: FSH, LH u amines § modified amino acids: epinephrine, melatonin § Lipid-based hormones u steroids § modified cholesterol: sex hormones, aldosterone AP Biology How do hormones act on target cells § Lipid-based hormones u hydrophobic & lipid-soluble § diffuse across cell membrane & enter cells § bind to receptor proteins in cytoplasm & nucleus § bind to DNA as transcription factors w turn on genes § Protein-based hormones u 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 AP Biology w enzyme action, uptake or secretion of molecules… Action of lipid (steroid) hormones steroid hormone target cell S S cytoplasm 1 blood S protein carrier cross cell membrane 2 binds to receptor protein becomes transcription factor 5 S 3 mRNA read by ribosome plasma membrane DNA nucleus 4 mRNA 6 protein 7 protein secreted AP Biology ex: secreted protein = growth factor (hair, bone, muscle, gametes) signal-transduction pathway Action of protein hormones 1 protein hormone P signal binds to receptor protein (G Protein) plasma membrane Activates Other protein activates enzyme cAMP receptor protein activates cytoplasmic signal GTP cytoplasm AP Biology target cell ATP ATP acts as 2° messenger transduction activates enzyme 2 secondary messenger system activates enzyme produces an action 3 response Ex: Action of epinephrine (adrenaline) adrenal gland signal 1 epinephrine activates G protein receptor protein in cell membrane activates GTP 3 activates adenylyl cyclase cAMP GTP 2 transduction 4 ATP activates protein kinase-A 5 activates phosphorylase kinase cytoplasm liver cell AP Biology released to blood activates glycogen phosphorylase glycogen 6 glucose 7 response Benefits of a 2° messenger system signal 1 Activated adenylyl cyclase receptor protein 2 Not yet activated amplification 4 3 GTP amplification cAMP 5 G protein 6 Amplification! amplification protein kinase amplification enzyme Cascade multiplier! AP Biology FAST response! 7 amplification product Maintaining homeostasis hormone 1 lowers body condition gland high specific body condition low raises body condition AP Biology gland hormone 2 Negative Feedback Model Nervous System Control Feedback Controlling Body Temperature nerve signals hypothalamus sweat dilates surface blood vessels high body temperature (37°C) low hypothalamus constricts surface shiver blood vessels AP Biology nerve signals Endocrine System Control Feedback Regulation of Blood Sugar islets of Langerhans insulin beta islet cells body cells take up sugar from blood pancreas liver stores glycogen liver high blood sugar level (90mg/100ml) low triggers hunger AP Biology liver releases glucose liver pancreas glucagon islets of Langerhans alpha islet cells reduces appetite Endocrine System Control Blood Osmolarity osmoreceptors in hypothalamus Feedback ADH increased water reabsorption pituitary nephron high nephron adrenal gland blood osmolarity blood pressure low increased water & salt reabsorption JuxtaGlomerular Apparatus nephron (JGA) renin aldosterone AP Biology increase thirst angiotensin angiotensinogen Nervous & Endocrine systems linked § Hypothalamus = “master nerve control center” nervous system u receives information from nerves around body about internal conditions u releasing hormones: regulates release of hormones from pituitary u § Pituitary gland = “master gland” endocrine system u secretes broad range of “tropic” hormones regulating other glands in body AP Biology hypothalamus u posterior pituitary anterior tropic hormones = target endocrine glands hypothalamus thyroid-stimulating hormone (TSH) Thyroid gland pic o r t o ortic CTH) c o n adre mone (A hor Adrenal cortex posterior antidiuretic pituitary hormone (ADH) anterior pituitary gonadotropic hormones: folliclestimulating hormone (FSH) & luteinizing hormone (LH) Kidney tubules Muscles of uterus Melanocyte in amphibian Bone and muscle AP Biology Testes Ovaries Mammary glands in mammals Homology in hormones What does this tell you about these hormones? How could these hormones have different effects? same gene family gene duplication? prolactin mammals milk production AP Biology birds fat metabolism fish amphibians salt & water balance metamorphosis & maturation growth hormone growth & development Regulating metabolism § Hypothalamus u TRH = TSH-releasing hormone § Anterior Pituitary u TSH = thyroid stimulating hormone § Thyroid u u produces thyroxine hormones metabolism & development § § § § § § § AP Biology bone growth mental development metabolic use of energy blood pressure & heart rate muscle tone digestion reproduction tyrosine + iodine thyroxines Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine + ✗ tyrosine + iodine AP Biology thyroxines ✗ Endocrine System Control Feedback Regulation of Blood Calcium calcitonin ↓ kidney reabsorption of Ca++ thyroid Ca++ deposited in bones high blood calcium level ↑ Ca++ uptake in intestines (10 mg/100mL) low activated Vitamin D bones release Ca++ AP Biology ↑ kidney reabsorption of Ca++ parathyroid parathyroid hormone (PTH) Feedback Female reproductive cycle egg matures & is released (ovulation) estrogen builds up uterus lining corpus luteum ovary progesterone FSH & LH maintains uterus lining pituitary gland yes pregnancy GnRH hypothalamus AP Biology fertilized egg (zygote) no corpus luteum breaks down progesterone drops menstruation hCG corpus luteum progesterone maintains uterus lining AP Biology Any Questions?? Robert Wadlow 1918-1940 8' 11" AP Biology 2009-2010 Effects of stress on a body Stress Nerve Spinal cord signals (cross section) Hypothalamus Releasing hormone Nerve cell adrenal medulla secretes epinephrine & norepinephrine Anterior pituitary Blood vessel Nerve cell ACTH Adrenal gland Adrenal cortex secretes mineralocorticoids & glucocorticoids Kidney (A) SHORT-TERM STRESS RESPONSE Effects of epinephrine and norepinephrine: 1. Glycogen broken down to glucose; increased blood glucose 2. Increased blood pressure 3. Increased breathing rate 4. Increased metabolic rate 5. Change in blood flow patterns, leading to increased alertness & decreased digestive & kidney activity AP Biology (B) LONG-TERM STRESS RESPONSE Effects of mineralocorticoids: Effects of glucocorticoids: 1. Retention of sodium ions & water by kidneys 1. Proteins & fats broken down & converted to glucose, leading to increased blood glucose 2. Increased blood volume & blood pressure 2. Immune system suppressed