2004-2005 AP Biology
Chapter 45.
Endocrine SystemHormones
2004-2005AP 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
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Regulation & Communication Animals rely on 2 systems for regulation
endocrine system ductless gland which secrete
chemical signals directly into blood chemical travels to target tissue slow, long-lasting response
nervous system system of neurons, central
nerve system transmits “electrical” signal to
target tissue fast, short-lasting response
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Regulation by chemical messengers
Axon Neurotransmitter
Endocrine gland
Receptor proteins
Hormonecarried by blood
Target cell
Neurotransmitters released by neurons Hormones release by endocrine glands
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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
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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
2004-2005AP BiologyNucleus
Cytoplasm
Steroid hormone (S) passes through plasma membrane.
Inside target cell, the steroid hormone binds to a specific receptor protein in the cytoplasm or nucleus.
Hormone-receptor complex enters nucleus & binds to DNA, causing gene transcription
Protein is produced.
Protein synthesis is induced.
Plasma membrane
DNA mRNAProtein
Steroidhormone
Blood plasma
Proteincarrier
1
2
2
3
3
5
5 4
4
S
S
S
1S
Action of steroid (lipid) hormones
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How do hormones act on target cellsSignal molecule
Cell surface receptorenzyme
G proteincAMP
Targetprotein
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.
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Action of protein hormones
3
4
GTPactivatesenzyme
activatesenzyme
activatesenzyme
Receptorprotein
cAMP
Proteinhormone
ATP
1
2
Cytoplasm
Produces an action
proteinmessengercascade
G protein
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adrenal gland
Action of epinephrine (adrenalin)
3
4
GTPactivates
protein kinase-A
activatesphosphorylase
activates adenylyl cyclase
Receptorprotein cAMP
Epinephrine
ATP
1
2
Cytoplasm
G protein
Liver cell
GlucoseGlycogen
releasedto blood
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Benefits of a 2° messenger system
Amplification!
Signal molecule Receptor protein Activated adenylyl cyclase
Amplification
Amplification
Amplification
Amplification
GTP G protein
2
1
3
4
5
6
7
Enzymatic product
Enzyme
Protein kinase
cAMP
Not yetactivated
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Ductless glands release hormones into blood
Endocrine system
Duct glands = exocrine(tears, salivary)
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Major vertebrate hormones (1)
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Major vertebrate hormones (2)
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Endocrine & Nervous system links 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
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Thyroid gland
Hypothalamus
Anteriorpituitary
Gonadotropic hormones:Follicle-stimulatinghormone (FSH) & luteinizing hormone (LH)
Mammaryglandsin mammals
Musclesof uterus
Kidneytubules
Posteriorpituitary
Thyroid-stimulating Hormone(TSH)
Antidiuretic hormone(ADH)
Adrenalcortex
Boneand muscle Testis Ovary
Melanocytein amphibian
Adrenocorticotropic
hormone (ACTH) Melanocyte-stimulating hormone(MSH)
OxytocinProlactin (PRL)
Growth
hor
mon
e (GH)
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Homology in hormones
prolactin
mammals birds amphibiansfish
milkproduction
fatmetabolism
metamorphosis& maturation
salt &water
balance
growthhormone
growth& development
What does this tell you about these hormones?same gene family
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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–
Inhibition
Target glands
Hypothalamus
Releasing hormones(TRH, CRH, GnRH)
Tropic hormones(TSH, ACTH, FSH, LH)
–
(thyroid, adrenal cortex, gonads)
Hormones
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- 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
pancreas
beta islet cells
alpha islet cells
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Regulating blood osmolarityIf amount of dissolved material in blood too high, need to dilute blood
ADH
Dehydration Lowers blood volume & pressure
Increased waterretention
Increasedvasoconstrictionleading to higherblood pressureReduced
urine volume
Osmotic concentrationof blood increases
ADH synthesized in hypothalamus
ADH released from posterior pituitary into blood
Osmoreceptors NegativefeedbackNegative
feedback
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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
tyrosineiodine
thyroxine
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GoiterIodine deficiency causes thyroid to enlarge as it tries to produce thyroxine
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Homology in hormones
Days from emergence of forelimb
TRH rises
TRH TSH Thyroxine
–35 –30 –25 –20 –15 –10 –5 0 +5 +10
Thyr
oxin
e se
cret
ion
rate
Thyroxine stimulates metamorphosis in amphibians
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Regulating blood calcium levels
Increased blood Ca++
Thyroid
ParathyroidsLow blood Ca++
Parathyroidhormone (PTH)
Increased absorptionof Ca++ from intestine due to PTH activation of Vitamin D
Reabsorption of Ca++ &excretion of PO4
Osteoclasts dissolve CaPO4crystals in bone, releasing Ca++
–Negativefeedback
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Hormonal regulation of insect development
Neurosecretory cells
Larval molt Pupal molt Adult molt
ProthoracicglandLow amounts
Brain hormone
Juvenile hormone
Molting hormone
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Any Questions??