Transcript Chapter 45.
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 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 3 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 Classes of Hormones Protein (peptide)-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 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… AP Biology 8 Paracrine Regulators Paracrine regulation occurs in most organs -Growth factors are proteins that promote growth and cell division in specific organs -Epidermal GF = Skin -Nerve GF = Neurons -Insulin-like GF = Bone -Cytokines = Immune system The endothelium of blood vessels is a rich source of paracrine regulators -Nitric oxide (NO) which promotes vasodilation -Endothelin which stimulates vasoconstriction Prostaglandins-A diverse group of fatty acids that are produced in almost every organ regulate a variety of functions including inflammation -Synthesis is inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen 9 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) 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 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 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 releasing hormones: regulates release of hormones from pituitary Pituitary gland = “master gland” Anterior pituitary (adenohypophysis) -Appears glandular -Posterior pituitary (neurohypophysis) -Appears hypothalamus fibrous endocrine system posterior secretes broad range of “tropic” hormones regulating other glands pituitary anterior AP Biology in body 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 The Anterior Pituitary The hypothalamus and the anterior pituitary are partially controlled by the very hormones whose secretion they stimulate -This is termed negative feedback or feedback inhibition Positive feedback is uncommon because it causes deviations from homeostasis -One example is the control of ovulation AP Biology 17 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 thyroxines Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine + tyrosine + iodine AP Biology ✗ ✗ thyroxines 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 Anterior Pituitary Disorders Growth hormone stimulates growth of muscles and connective tissue -It also promotes the production of insulinlike growth factors -Stimulate cell division in the epiphyseal growth plates, and thus bone elongation Gigantism is caused by an excessive secretion of growth hormone in a child AP Biology 23 Anterior Pituitary Disorders AP Biology 24