Sinh học - Chương 40: Warm - Up

Ch. 40 Warm-UpWhat type of behavior in animals might be triggered by cold temperatures?What type of behaviors might be triggered in hot temperatures?List 2 examples of negative feedback. List 2 examples of positive feedback.What is the main type of chemical messenger in the endocrine system? The nervous system?Warm-UpCompare and contrast the nervous system with the endocrine system. (Focus on the effects on the body)Define neurosecretory cell. What is its function?Give an example of positive and negative feedback in the endocrine system. How do they function?Ch. 45 Warm-UpCompare peptide hormones to steroids.Explain how insulin and glucagon work to regulate blood sugar levels.Which glands and hormones respond when your body is under stress?Chapter 45Hormones and the Endocrine SystemA hormone called ecdysteroid regulates the timing of metamorphosis in this anise swallowtail butterfly.You must know:Two ways hormones affect target organs.The secretion, target, action, and regulation of at least 3 hormones.An illustration of both positive and negative feedback in the regulation of homeostasis by hormones.Types of Intercellular SignalingEndocrine System = Hormone-secreting cells + TissuesEndocrine glands: ductless, secrete hormones directly into body fluidsHormones: chemical signals that cause a response in target cells (receptor proteins for specific hormones)Affects 1 tissue, a few, or most tissues in bodyOr affect other endocrine glands (tropic hormones)Regulation by Positive & Negative FeedbackPheromonesHormonesLocal RegulatorsChemical signal from 1 individual to another individualChemical signal from endocrine gland through blood to target cellChemical signal from one cell to an adjacent cellEg. ant trail; sex phermonesEg. peptide, steroid hormonesEg. cytokines, growth factors, nitric oxide (NO)Discovery Video: Endocrine SystemTypes of HormonesPeptideWater-solubleBind to receptors on plasma membrane & triggers signal transduction pathwayAffects protein activity already present in cellRapid responseShort-livedEg. oxytocin, insulin, epinephrineSteroidLipid-solubleEnters cell & binds to intracellular receptorsCauses change in gene expression (protein synthesis)Slower responseLonger lifeEg. androgens (testosterone), estrogen, progesterone, cortisolEpinephrine: one hormone  many effectsLiver cells break down glycogen and release glucoseBlood vessels to skeletal muscles dilateBlood vessels to intestines constrictHypothalamusPituitary GlandMaster GlandsHypothalamusPituitary GlandReceives info from nerves and brainInitiates endocrine signalsPosterior pituitary gland:Oxytocin: contract uterine muscles, eject milk in nursingAntidiuretic Hormone (ADH): promote H2O retention by kidneysAnterior pituitary gland:Follicle-stimulating hormone (FSH): development of ovarian follicles (eggs); promote sperm productionLuteinizing hormone (LH): trigger ovulation; stimulate testosterone production in testesMaster GlandsHypothalamus regulation of Posterior Pituitary glandHypothalamus regulation of Anterior Pituitary glandNegative feedback systems: Thyroid hormonesBlood Ca2+ levelsBlood glucose levelsPositive feedback system:Oxytocin (birthing process; release of milk/suckling)BIOFLIX: HOMEOSTASIS – BLOOD SUGARInsulin & Glucagon: Control blood glucose levelsControl of Blood GlucoseHigh blood glucoseInsulin released from pancreasBody cells take up glucoseLiver stores glucose as glycogenBlood glucose dropsGlucagon released from pancreasLiver breaks down glycogen and releases glucose into bloodDiabetes MellitusType I diabetes (10%):deficiency of insulinInsulin-dependentAutoimmune disorder  beta cells of pancreas destroyedType II diabetes (90%): failure of target cells to respond to insulinNon-insulin dependentInsulin produced  cells don’t respond (defect in insulin receptor or response pathway)Risk factors: obesity, lack of exerciseThyroid GlandHypothalamusTRHAnteriorpituitaryTSHThyroidT3T4Graves’ Disease:Autoimmune disorderAntibodies bind to TSH receptorHyperthyroidismHigh temp, sweating, weight loss, high BPStress and the Adrenal GlandAnabolic-Androgenic Steroid (AAS) UseLegally prescribed to treat hormone deficiency, loss of muscle mass (cancer, AIDS)Used to enhance performance and improve physical appearanceEffects of AAS AbuseSource: www.drugabuse.gov/infofacts/steroids.htmlaggressionextreme mood swingsliver damagejaundicefluid retentionhigh blood pressureincreases in LDL (“bad” cholesterol)decreases in HDL (“good” cholesterol)renal failuresevere acneFor men—shrinking of the testicles, reduced sperm count, infertility, baldness, development of breasts, increased risk for prostate cancerFor women—growth of facial hair, male-pattern baldness, changes in or cessation of the menstrual cycle, enlargement of the clitoris, deepened voiceFor adolescents—stunted growth due to premature skeletal maturation and accelerated puberty changes; risk of not reaching expected height if AAS is taken before the typical adolescent growth spurtIn addition, people who inject AAS run the added risk of contracting or transmitting HIV/AIDS or hepatitis.