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Endocrine System Hormones AP Biology 2007-2008 Regulation Why are hormones needed? chemical messages from one body part to another communication needed to coordinate whole body homeostasis & regulation metabolism growth development maturation reproduction AP Biology growth hormones 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 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 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 How do hormones act on target cells Lipid-based hormones hydrophobic & lipid-soluble diffuse across membrane & enter cells bind to receptor proteins in cytoplasm & nucleus bind to DNA as transcription factors Protein-based hormones hydrophilic & not lipid soluble can’t diffuse across membrane receptor proteins in cell membrane trigger secondary messenger pathway activate internal cellular response enzyme action, uptake or secretion of molecules… AP Biology Action of lipid (steroid) hormones steroid hormone target cell S S cytoplasm S 1 2 blood protein carrier receptor protein 4 transcription factor S 3 DNA nucleus AP Biology mRNA 5 protein plasma membrane ex: growth factors (hair, bone, muscle, gametes) Action of protein hormones signal-transduction pathway 1 protein hormone P signal plasma membrane activates ion channel or enzyme 2° messenger receptor protein transduction ATP activates enzyme cytoplasm AP target Biology cell 2 secondary messenger system activates enzyme produces an action 3 response Signal Transduction pathway 1 protein hormone P activates enzyme G protein cAMP receptor protein 2 GTP cytoplasm AP Biology 3 ATP activates enzyme activates enzyme produces an action secondary messenger system 4 5 Action of epinephrine (adrenalin) 1 epinephrine activates adenylyl cyclase adrenal gland activates G protein cAMP GDP receptor protein 3 GTP 2 ATP activates protein kinase-A 4 activates phosphorylase kinase cytoplasm liver cell AP Biology released to blood activates glycogen phosphorylase glycogen 5 glucose 6 Benefits of a 2° messenger system signal 1 Activated adenylyl cyclase receptor protein 2 Not yet activated amplification 4 3 GTP amplification cAMP amplification 5 G protein protein kinase 6 amplification enzyme Amplification! 7 FAST response! AP Biology 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 dilates surface blood vessels sweat 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 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 Endocrine System Control Blood Osmolarity osmoreceptors in hypothalamus Feedback 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 Nervous & Endocrine systems linked Hypothalamus = “master nerve control center” nervous system receives information from nerves around body about internal conditions regulates release of hormones from pituitary Pituitary gland = “master gland” endocrine system secretes broad range of hormones regulating other glands hypothalamus posterior pituitary AP Biology anterior tropic hormones hypothalamus thyroid-stimulating hormone (TSH) Thyroid gland posterior antidiuretic pituitary hormone (ADH) anterior pituitary Kidney tubules Muscles of uterus Adrenal cortex gonadotropic hormones: folliclestimulating hormone (FSH) & luteinizing hormone (LH) Melanocyte in amphibian Bone and muscle AP Biology Testis Ovary 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 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 thyroxine Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine AP Biology 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 hCG yes pregnancy GnRH hypothalamus AP Biology fertilized egg (zygote) no corpus luteum breaks down progesterone drops menstruation corpus luteum progesterone maintains uterus lining 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 Any Questions?? Robert Wadlow 1918-1940 8' 11" AP Biology 2007-2008