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Endocrine System Hormones AP Biology 2007-2008 AP Biology Regulation & Communication Animals rely on 2 systems for regulation endocrine system system of ductless glands secrete chemical signals directly into blood chemical travels to target tissue target cells have receptor proteins slow, long-lasting response nervous system system of neurons transmits “electrical” signal & release neurotransmitters to target tissue 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 Regulation Why are hormones needed? chemical messages from one body part to another communication needed to coordinate whole body daily homeostasis & regulation of large scale changes solute levels in blood glucose, Ca++, salts, etc. metabolism growth development maturation AP Biology reproduction growth hormones AP Biology AP Biology AP Biology AP Biology tropic hormones = target endocrine glands hypothalamus thyroid-stimulating hormone (TSH) Thyroid gland 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 Refer to chart AP Biology 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 AP Biology 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… Classes of Hormones Protein-based hormones polypeptides small proteins: insulin, ADH insulin glycoproteins large proteins + carbohydrate: FSH, LH amines modified amino acids: epinephrine, melatonin Lipid-based hormones steroids modified cholesterol: sex hormones, aldosterone AP Biology AP Biology AP Biology AP Biology 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 4 mRNA nucleus 6 protein 7 protein secreted AP Biology ex: secreted protein = growth factor (hair, bone, muscle, gametes) AP Biology AP Biology AP Biology Benefits of a 2° messenger system1 signal Activated adenylyl cyclase receptor protein 2 Not yet activated amplification 4 3 GTP amplification cAMP amplification 5 G protein protein kinase 6 amplification Amplification! enzyme Cascade multiplier! AP Biology FAST response! 7 amplification product AP Biology signal-transduction pathway Action of protein hormones 1 protein hormone P signal plasma membrane binds to receptor protein activates G-protein activates enzyme cAM P receptor protein activates cytoplasmic signal GTP cytoplasm AP Biology target cell acts as 2° messenger transduction ATP ATP 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 GDP transduction 4 GTP 2 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 AP Biology estres estrogen progesterone testosterone AP Biology Nervous & Endocrine systems linked Hypothalamus = “master nerve control center” nervous system receives information from nerves around body about internal conditions releasing hormones: regulates release of hormones from pituitary Pituitary gland = “master gland” AP Biology endocrine system secretes broad range of “tropic” hormones regulating other glands in body hypothalamus posterior pituitary anterior Negative feedback loop AP Biology #1 Regulating metabolism Hypothalamus TRH = TSH-releasing hormone Anterior Pituitary TSH = thyroid stimulating hormone Thyroid 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 #2 Nervous System Control Feedback Controlling Body Temperature nerve signals hypothalamus dilates surface blood vessels sweat high body temperature (37°C) low hypothalamus constricts surface shiver blood vessels AP Biology nerve signals #3 Feedback Regulation of Blood Sugar islets of Langerhans insulin beta islet cells liver stores glycogen body cells take up sugar from blood pancreas 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 Be able to write on diabetes AP Biology #4 Feedback Blood Osmolarity osmoreceptors in hypothalamus ADH increased water reabsorption pituitary increase thirst nephron high blood osmolarity blood pressure nephron adrenal gland low increased water & salt reabsorption JuxtaGlomerular Apparatus nephron (JGA) renin aldosterone AP Biology angiotensinogen angiotensin #5 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 hCG yes pregnancy GnRH hypothalamus AP Biology fertilized egg (zygote) no corpus luteum breaks down progesterone drops menstruation corpus luteum progesterone maintains uterus lining AP Biology Any Questions?? Robert Wadlow 1918-1940 8' 11" AP Biology 2009-2010 Positive feedback Oxytocin Fruit ripening AP Biology Effects of stress on a body Stress Nerve Spinal cord signals (cross section) Hypothalamus Releasing hormone Nerve cell Anterior pituitary Blood vessel adrenal medulla secretes epinephrine & norepinephrine 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