Download Chapter 45 Hormones and Endocrine system

Endocrine System
Hormones
AP Biology
2006-2007
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
 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
 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

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

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
 trigger secondary messenger pathway
 activate cellular response
 enzyme action, uptake or secretion of molecules…
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Action of lipid (steroid) hormones
cytoplasm
steroid hormone
S
S
S
1
2
blood
protein
carrier
receptor protein
4
S
3
DNA
nucleus
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mRNA
5 protein
plasma membrane
Action of protein hormones
1
Protein
hormone
activates
enzyme
G protein
cAMP
Receptor
protein
3
2
ATP
GTP
activates
enzyme
activates
enzyme
cytoplasm
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4
Produces an action
protein
messenger
cascade
Action of epinephrine (adrenalin)
liver cell
1
epinephrine
activates
adenylyl cyclase adrenal gland
G protein
cAMP
receptor
protein
2
3
ATP
GTP
activates
protein kinase-A
activates
phosphorylase
4
cytoplasm
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glycogen
glucose
released
to blood
Benefits of a 2° messenger system
1
Signal molecule
Receptor protein
Activated adenylyl cyclase
Not yet
activated
2 Amplification
4 Amplification
3
GTP
cAMP
5
G protein
Protein kinase
6 Amplification
Amplification!
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Enzyme
7 Amplification
Enzymatic product
Negative Feedback Model
hormone 1
lowers
body condition
gland
high
specific body condition
low
raises
body condition
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gland
hormone 2
2005-2006
Nervous System Control
Body Temperature
Feedback
nerve signals
brain
sweat
dilates surface
blood vessels
high
body temperature
low
brain
constricts surface shiver
blood vessels
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nerve signals
2005-2006
Endocrine System Control
Blood Sugar
Feedback
insulin
liver stores
sugar
body
cells take
up sugar
from blood
pancreas
high
reduces
appetite
liver
blood sugar level
low
triggers
hunger
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liver
releases
sugar
liver
pancreas
glucagon
2005-2006
Endocrine System Control
Blood Osmolarity
Feedback
ADH
increased
water
reabsorption
pituitary
increase
thirst
nephron
high
blood osmolarity
blood pressure
adrenal
gland
low
increased
water & salt
reabsorption
nephron
renin
aldosterone
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angiotensinogen
angiotensin
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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”


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endocrine system
secretes broad range
of hormones
regulating other
glands
Hypothalamus
Thyroid-stimulating
Antidiuretic
Hormone
Posterior
hormone
(TSH)
pituitary (ADH)
Thyroid gland
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
Homology in hormones
What does this tell you about these hormones?
same gene family
prolactin
mammals
milk
production
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birds
fat
metabolism
fish
amphibians
salt &
water
balance
metamorphosis
& maturation
growth
hormone
growth
& development
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
Goiter
Iodine deficiency
causes thyroid to
enlarge as it tries to
produce thyroxine
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Regulating blood calcium levels
Thyroid
Low blood Ca++
–
Negative
feedback
Increased absorption
of Ca++ from intestine
due to PTH activation
of Vitamin D
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Parathyroids
Parathyroid
hormone (PTH)
Reabsorption of Ca++ &
excretion of PO4
Increased blood Ca++
Osteoclasts
dissolve CaPO4
crystals in
bone, releasing
Ca++
Feedback
Female reproductive cycle
egg
matures &
is released
(ovulation)
estrogen
builds up
uterus lining
corpus
luteum
ovary
progesterone
FSH & LH
maintains
uterus lining
fertilized egg
(zygote)
HCG
yes
pituitary
gland
pregnancy
GnRH
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hypothalamus
no
corpus luteum breaks down
progesterone drops
menstruation
corpus
luteum
progesterone
maintains
2005-2006
uterus lining
Any Questions??
AP Biology
2005-2006