Hormones AP Biology 2007-2008 Regulation Why are hormones needed? - PowerPoint PPT Presentation

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 receptor proteins AP Biology 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 signal transduction pathway  activate internal cellular response  enzyme action, uptake or secretion of molecules… AP Biology

Action of lipid (steroid) hormones steroid hormone target cell blood S S 1 protein S carrier 2 cytoplasm receptor protein 4 transcription factor S 3 DNA 5 mRNA plasma membrane protein nucleus AP Biology ex: growth factors (hair, bone, muscle, gametes)

Action of protein hormones signal-transduction pathway 1 signal protein P plasma membrane hormone activates ion channel or enzyme 2° messenger receptor protein transduction ATP activates 2 enzyme Signal transduction activates cytoplasm pathway enzyme produces an action response 3 AP Biology target cell

Action of epinephrine (adrenalin) epinephrine 1 activates adenylyl cyclase adrenal gland activates G protein cAMP GDP receptor 3 protein 2 ATP activates 4 GTP protein kinase-A activates phosphorylase kinase cytoplasm released activates to blood glycogen phosphorylase 6 glycogen glucose 5 liver cell AP Biology

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

Nervous System Control Feedback Controlling Body Temperature nerve signals hypothalamus sweat dilates surface blood vessels high body temperature (37°C) low hypothalamus constricts surface shiver blood vessels AP Biology nerve signals

Endocrine System Control Feedback Regulation of Blood Sugar insulin beta islet cells body liver stores reduces cells take glycogen appetite pancreas up sugar from blood liver high blood sugar level (90mg/100ml) low liver triggers releases pancreas hunger glucose AP Biology glucagon alpha islet cells liver

Endocrine System Control Feedback Blood Osmolarity osmoreceptors in ADH hypothalamus increased increase water thirst reabsorption pituitary nephron high blood osmolarity JuxtaGlomerular Apparatus nephron low increased nephron adrenal water & salt gland (JGA) reabsorption renin aldosterone angiotensinogen AP Biology angiotensin

COLLECTING INTERSTITIAL Osmoreceptors in FLUID DUCT hypothalamus trigger LUMEN release of ADH. Thirst Hypothalamus COLLECTING DUCT CELL ADH ADH receptor cAMP Drinking reduces blood osmolarity ADH to set point. Second messenger Pituitary signaling molecule Increased gland permeability Storage Distal vesicle tubule Exocytosis Aquaporin water H 2 O channels H 2 O reab- H 2 O STIMULUS: sorption helps Increase in blood prevent further osmolarity osmolarity increase. Collecting duct (b) Homeostasis: Blood osmolarity (300 mOsm/L) (a) AP Biology

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 hypothalamus  secretes broad range of hormones regulating other posterior glands pituitary anterior 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 tyrosine  reproduction + iodine AP Biology 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 thyroid Ca ++ deposited reabsorption of Ca ++ in bones high blood calcium level (10 mg/100mL)  Ca ++ uptake low in intestines activated Vitamin D  kidney parathyroid reabsorption bones of Ca ++ release Ca ++ AP Biology parathyroid hormone (PTH)

Feedback Female reproductive cycle egg builds up estrogen matures & uterus lining is released (ovulation) corpus ovary luteum progesterone fertilized egg FSH & LH (zygote) maintains uterus lining pituitary hCG gland yes corpus luteum pregnancy no progesterone GnRH hypothalamus corpus luteum breaks down maintains progesterone drops AP Biology uterus lining menstruation