AP Biology Endocrine System Hormones

AP Biology 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 growth hormones

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  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 axon endocrine gland receptor proteins target cell  Neurotransmitters released by neurons  Hormones release by endocrine glands receptor proteins hormone carried by blood neurotransmitter

AP Biology Classes of Hormones  Protein-based hormones  polypeptides  small proteins: insulin, ADH  glycoproteins  large proteins + carbohydrate: FSH, LH  amines  modified amino acids: epinephrine, melatonin  Lipid-based hormones  steroids  modified cholesterol: sex hormones, aldosterone insulin

AP Biology How do hormones act on target cells  Lipid-based hormones  lipid-soluble  diffuse across membrane & enter cells  bind to receptor proteins in cytoplasm & then this hormone-receptor complex moves into nucleus  bind to receptor proteins in nucleus  bind to DNA as transcription factors

AP Biology nucleus target cell plasma membrane DNA mRNA protein steroid hormone blood protein carrier S S S S Action of lipid (steroid) hormones receptor protein cytoplasm transcription factor ex: growth factors (hair, bone, muscle, gametes)

AP Biology How do hormones act on target cells Signal molecule Cell surface receptor enzyme G protein cAMP Target protein Nucleus Cytoplasm ATP  Protein-based hormones  hydrophilic & not lipid soluble  can’t diffuse across membrane  trigger secondary (2°) messenger pathway  transmit “signal” across membrane  “signal transduction”  usually activates a series of 2° messengers  multi-step “cascade”  activate cellular response  enzyme action, uptake or secretion of molecules, etc.

AP Biology Action of protein hormones activates enzyme activates enzyme activates ion channel or enzyme protein hormone ATP produces an action transduction P cytoplasm receptor protein response signal secondary messenger system signal-transduction pathway 2° messenger target cell plasma membrane

AP Biology Signal Transduction pathway GTP activates enzyme activates enzyme activates enzyme protein hormone ATP produces an action secondary messenger system G protein P receptor protein cytoplasm 5 cAMP

AP Biology adrenal gland Action of epinephrine (adrenalin) GTP activates protein kinase-A activates phosphorylase activates adenylyl cyclase epinephrine ATP G protein liver cell released to blood receptor protein cytoplasm 5 glycogenglucose cAMP

AP Biology Benefits of a 2° messenger system Amplification! signal receptor protein Activated adenylyl cyclase amplification GTPG protein product enzyme protein kinase cAMP Not yet activated FAST response! amplification

AP Biology Hormones & Homeostasis  Negative feedback  stimulus triggers control mechanism that inhibits further change  body temperature  sugar metabolism  Positive feedback  stimulus triggers control mechanism that amplifies effect  lactation  labor contractions Anterior pituitary Inhibition – Target glands Hypothalamus Releasing hormones (TRH, CRH, GnRH) Tropic hormones (TSH, ACTH, FSH, LH) – (thyroid, adrenal cortex, gonads) Hormones

AP Biology Maintaining homeostasis high low hormone 1 lowers body condition hormone 2 gland specific body condition raises body condition gland Negative Feedback Model

AP Biology Controlling Body Temperature high low nerve signals sweat nerve signals brain body temperature shiver brain dilates surface blood vessels constricts surface blood vessels Nervous System Control Feedback

AP Biology liver pancreas liver Regulation of Blood Sugar blood sugar level insulin body cells take up sugar from blood liver stores sugar reduces appetite pancreas liver releases sugar triggers hunger high low Feedback Endocrine System Control

AP Biology triggers release of glucose by liver - stimulates appetite Regulating blood sugar levels -triggers uptake of glucose by body cells -triggers storage in liver - depresses appetite pancreas beta islet cells alpha islet cells

AP Biology Nervous & Endocrine systems linked  Hypothalamus = “master 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 pituitary anterior posterior

AP Biology Regulating metabolism  Hypothalamus  TRH = TSH-releasing hormone  Anterior Pituitary  TSH = thyroid stimulating hormone  Thyroid  produces thyroxine hormones  metabolism & development  bone growth  mental development  metabolic use of energy  blood pressure & heart rate  muscle tone  digestion  reproduction tyrosine + iodine thyroxine

AP Biology Thyroid gland Hypothalamus anterior pituitary gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) Mammary glands in mammals Muscles of uterus Kidney tubules posterior pituitary thyroid-stimulating hormone (TSH) antidiuretic hormone (ADH) Adrenal cortex Bone and muscle Testis Ovary Melanocyte in amphibian adrenocorticotropic hormone (ACTH) melanocyte-stimulating hormone (MSH) oxytocin prolactin (PRL) growth hormone (GH)

AP Biology Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine

AP Biology Any Questions?? Robert Wadlow ' 11"