Endocrine System Communication using Hormones AP Biology 2007

Endocrine System Communication using Hormones AP Biology 2007 -2008

Big Questions Why is communication between cells necessary? How is cellular communication used among unicellular and multicellular life? How do mechanisms of cellular communication demonstrate a shared evolutionary history among organisms? AP Biology

Why Communicate? Communication between cells allows for the exchange of information The exchange of information between cells allows for coordination and regulation among cells. The evolution of communication in cells has been demonstrated in all domains of life. AP Biology

Three major steps of cellular communication 1. Reception of a chemical message 2. 3. (aka “ligand”) Transduction of the message into the cell. Cellular response. These three steps are universal across all domains of life. AP Biology

Multicellular Communication The cells of a multicellular organism are in constant communication. The purpose of this communication is largely for regulation of organismal physiology. Cellular responses support the functioning of the organism as a whole AP Biology

Regulation § Why are hormones needed? chemical messages from one body part to another u communication needed to coordinate whole body u daily homeostasis & regulation of large scale changes u § solute levels in blood w glucose, Ca++, salts, etc. § metabolism § growth § development § maturation AP Biology § reproduction growth hormones

Regulation & Long Distance 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 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-based hormones u polypeptides § small proteins: insulin, ADH u insulin glycoproteins § large proteins + carbohydrate: FSH, LH u amines § modified amino acids: epinephrine, melatonin § Lipid-based hormones u steroids § modified cholesterol: sex hormones, aldosterone AP Biology

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 § § AP Biology 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 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 m. RNA read by ribosome plasma membrane DNA nucleus 4 m. RNA 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 binds to receptor protein plasma membrane activates G-protein activates enzyme c. AMP receptor protein activates cytoplasmic signal GTP cytoplasm AP Biology target cell ATP acts as 2° messenger transduction 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 c. AMP GDP GTP 2 transduction 4 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

Benefits of a 2° messenger system signal 1 Activated adenylyl cyclase receptor protein 2 Not yet activated amplification 4 3 GTP amplification c. AMP 5 G protein 6 Amplification! amplification protein kinase amplification enzyme Cascade multiplier! AP Biology FAST response! 7 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 Regulation of Blood Sugar insulin islets of Langerhans beta islet cells liver stores glycogen body cells take up sugar from blood pancreas Feedback liver high blood sugar level (90 mg/100 ml) 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 nephron high nephron adrenal gland blood osmolarity blood pressure increased water & salt reabsorption low Juxta. Glomerular Apparatus nephron (JGA) renin aldosterone AP Biology increase thirst angiotensinogen

Nervous & Endocrine systems linked § Hypothalamus = “master nerve control center” u u u nervous system receives information from nerves around body about internal conditions releasing hormones: regulates release of hormones from pituitary § Pituitary gland = “master gland” u u AP Biology endocrine system secretes broad range of “tropic” hormones regulating other glands in body hypothalamus posterior pituitary anterior

tropic hormones = target endocrine glands hypothalamus thyroid-stimulating hormone (TSH) Thyroid gland opic r t o c orti CTH) c o n adre mone (A hor e on rm ho th ow ) RL (P gr tin ac ol Adrenal cortex pr (G H) posterior antidiuretic pituitary hormone (ADH) anterior Kidney pituitary oxy tubules m t o el cin an oc Muscles yt eof uterus s t gonadotropic im ul hormones: at in follicleg ho stimulating rm hormone (FSH) (M on SH e & luteinizing ) hormone (LH) Melanocyte in amphibian Bone and muscle AP Biology Testes Ovaries 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 u TRH = Thyroid-releasing hormone § Anterior Pituitary u TSH = thyroid stimulating hormone § Thyroid u u 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 ✗

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/100 m. L) low activated Vitamin D bones release Ca++ AP Biology kidney reabsorption of Ca++ 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 yes pregnancy Gn. RH hypothalamus AP Biology fertilized egg (zygote) no corpus luteum breaks down progesterone drops menstruation h. CG corpus luteum progesterone maintains uterus lining

AP Biology

Effects of stress on a body Stress Nerve Spinal cord signals (cross section) Hypothalamus Releasing hormone Nerve cell adrenal medulla secretes epinephrine & norepinephrine Anterior pituitary Blood vessel Nerve cell ACTH Adrenal gland Kidney A L L U D (A) SHORT-TERM STRESS RESPONSE ME 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 Adrenal cortex secretes mineralocorticoids & glucocorticoids CO (B) LONG-TERM STRESS RESPONSE RT EX 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