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