Download Ch45endocrine

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
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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
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Regulation by chemical messengers
 Neurotransmitters released by neurons
 Hormones release by endocrine glands
endocrine gland
neurotransmitter
axon
hormone
carried by blood
receptor proteins
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receptor proteins
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
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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

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bind to DNA as transcription factors
2004-
Action of lipid (steroid) hormones
steroid hormone
target cell
S
S
cytoplasm
S
1
2
blood
protein
carrier
receptor protein
4
transcription
factor
S
3
DNA
nucleus
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mRNA
5 protein
plasma membrane
ex: growth factors (hair, bone, muscle, gametes)
How do hormones act on target cells
 Protein-based hormones

hydrophilic & not lipid
soluble
Signal molecule
Cell surface receptor
enzyme
 can’t diffuse across
cAMP
membrane

trigger secondary (2°)
messenger pathway
G protein
ATP
 transmit “signal” across
membrane
 “signal transduction”
 usually activates a series of
2° messengers
 multi-step “cascade”

Nucleus
activate cellular response
 enzyme action, uptake or
AP Biology
Target
protein
secretion of molecules, etc.
Cytoplasm
2004-
Action of protein hormones
signal-transduction pathway
1
protein
hormone
P
signal
plasma membrane
activates ion channel
or enzyme
2° messenger
receptor
protein
transduction
ATP
activates
enzyme
cytoplasm
AP target
Biology
cell
2
secondary
messenger
system
activates
enzyme
produces an action
3
response
Signal Transduction pathway
1
protein hormone P
activates
enzyme
G protein
cAMP
receptor
protein
2
GTP
cytoplasm
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3
ATP
activates
enzyme
activates
enzyme
produces an action
secondary
messenger
system
4
5
Action of epinephrine (adrenalin)
1
epinephrine
activates
adenylyl cyclase adrenal gland
G protein
cAMP
receptor
protein
2
GTP
cytoplasm
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liver
cell
3
ATP
activates
protein kinase-A
activates
phosphorylase
glycogen
5
4
glucose
released
to blood
Benefits of a 2° messenger system
signal
1
Activated adenylyl cyclase
receptor protein
2
Not yet
activated
amplification
4
3
GTP
amplification
cAMP
amplification
5
G protein
protein kinase
6
amplification
enzyme
Amplification!
7
FAST
response!
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amplification
product
Hormones & Homeostasis
 Negative feedback Inhibition Hypothalamus

stimulus triggers
control mechanism
that inhibits further
change
 body temperature
 sugar metabolism
 Positive feedback

stimulus triggers
control mechanism
that amplifies effect
 lactation
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 labor contractions
–
Releasing hormones
(TRH, CRH, GnRH)
Inhibition
Anterior pituitary
Tropic hormones
(TSH, ACTH, FSH, LH)
Target glands
(thyroid, adrenal cortex, gonads)
Hormones
2004-
–
Maintaining homeostasis
hormone 1
lowers
body condition
gland
high
specific body condition
low
raises
body condition
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gland
hormone 2
Negative Feedback
Model
Nervous System Control
Feedback
Controlling Body Temperature
nerve signals
brain
sweat
high
body temperature
low
brain
constricts surface shiver
blood vessels
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nerve signals
dilates surface
blood vessels
Endocrine System Control
Regulation of Blood Sugar
Feedback
insulin
liver stores
sugar
body
cells take
up sugar
from blood
pancreas
high
liver
blood sugar level
low
triggers
hunger
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liver
releases
sugar
liver
pancreas
reduces
appetite
Regulating blood sugar levels
beta islet cells
pancreas
- triggers
release of
glucose by
liver
- stimulates
appetite
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- triggers uptake
of glucose by
body cells
- triggers
storage in liver
- depresses
appetite
pancreas
2004alpha islet
cells
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
anterior
pituitary
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posterior
Regulating metabolism
 Hypothalamus

TRH = TSH-releasing hormone
 Anterior Pituitary

TSH = thyroid stimulating hormone
 Thyroid


produces thyroxine hormones
metabolism & development







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bone growth
mental development
metabolic use of energy
blood pressure & heart rate
muscle tone
digestion
reproduction
tyrosine
+
iodine
thyroxine
Hypothalamus
thyroid-stimulating
hormone
(TSH)
Thyroid gland
antidiuretic
posterior hormone
pituitary (ADH)
anterior
pituitary
Kidney
tubules
Muscles
of uterus
Adrenal
cortex
gonadotropic
hormones:
folliclestimulating
hormone (FSH)
& luteinizing
hormone (LH)
Melanocyte
in amphibian
Bone
and muscle
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Testis
Ovary
Mammary
glands
in mammals
Goiter
Iodine deficiency
causes thyroid to
enlarge as it tries to
produce thyroxine
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Any Questions??
Robert Wadlow
1918-1940
8' 11"
AP Biology
2007-2008