Transcript Endocrine System 2013-2014 with four embedded videos

Endocrine System
Hormones
2007-2008
Animals rely on 2 systems for regulation
(Watch Mr.A – (#1) Cell Communication Video)

endocrine system
 system of ductless glands
 secrete chemical signals directly into blood
 chemical travels to target tissue
 target cells have receptor proteins
 slow, long-lasting response

nervous system
 system of neurons
 transmits “electrical” signal &
release neurotransmitters to
target tissue
 fast, short-lasting response
Regulation
 Why are hormones needed?
chemical messages from one
body part to another
 communication needed to
coordinate whole body
 daily homeostasis & regulation of
large scale changes

 solute levels in blood
 glucose, Ca++, salts, etc.
 metabolism
 growth
 development
 maturation
 reproduction
growth hormones
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
target cell
Lock & Key
system
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
How do hormones act on target cells
 Lipid-based hormones

hydrophobic & lipid-soluble
 diffuse across cell membrane & enter cells
 bind to receptor proteins in cytoplasm & nucleus
 bind to DNA as transcription factors
 turn on genes
 Protein-based hormones

hydrophilic & not lipid soluble




can’t diffuse across cell membrane
bind to receptor proteins in cell membrane
trigger secondary messenger pathway
activate internal cellular response
 enzyme action, uptake or secretion of molecules…
Action of lipid (steroid) hormones
steroid hormone
target cell
S
S
cytoplasm
1
blood
S
protein
carrier
cross cell membrane
2
binds to receptor protein
becomes
transcription factor
5
S
3
mRNA read by ribosome
plasma membrane
4
DNA
mRNA
nucleus
6
protein
7
protein secreted
ex: secreted protein = growth factor (hair, bone, muscle, gametes)
See Mr. A’s
signal-transduction pathway (#2) Video NOW
Action of protein hormones
1
protein
hormone
P
signal
plasma membrane
binds to receptor protein
activates
G-protein
activates enzyme
cAM
P
receptor
protein
activates
cytoplasmic
signal
GTP
cytoplasm
target cell
acts as 2° messenger
transduction
ATP
ATP
activates
enzyme
2
secondary
messenger
system
activates
enzyme
produces an action
3
response
Ex: Action of epinephrine (adrenaline)
on liver cells
adrenal gland
signal
1
epinephrine
activates
G protein
receptor
protein
in cell
membrane
activates GTP
3
activates
adenylyl cyclase
cAMP
GDP
transduction
4
GTP
2
ATP
activates
protein kinase-A
5
activates
phosphorylase kinase
cytoplasm
liver cell
released
to blood
activates
glycogen phosphorylase
glycogen
6
glucose
7
response
Benefits of a 2° messenger
system1
signal
Activated adenylyl cyclase
receptor protein
2
Not yet
activated
amplification
4
3
GTP
amplification
cAMP
amplification
5
G protein
protein kinase
6
amplification
Amplification!
enzyme
Cascade multiplier!
FAST response!
7
amplification
product
Maintaining homeostasis
hormone 1
lowers
body condition
gland
high
specific body condition
low
raises
body condition
gland
hormone 2
Negative Feedback
Model
Nervous System Control
Feedback
Controlling Body Temperature
nerve signals
hypothalamus
dilates surface
blood vessels
sweat
high
body temperature
(37°C)
low
hypothalamus
constricts surface shiver
blood vessels
nerve signals
Endocrine System Control
Regulation of Blood Sugar
Feedback
insulin
liver stores
glycogen
body
cells take
up sugar
from blood
pancreas
liver
high
blood sugar level
(90mg/100ml)
low
triggers
hunger
liver
releases
glucose
liver
pancreas
glucagon
reduces
appetite
What is the effect of changes in
the signal transduction pathways?
Watch this Video (#3)to find out!
Nervous & Endocrine systems linked
 Hypothalamus = “master nerve control center”



nervous system
receives information from nerves around body
about internal conditions
releasing hormones: regulates release of hormones
from pituitary
 Pituitary gland = “master gland”


endocrine system
secretes broad range
of “tropic” hormones
regulating other
glands in body
hypothalamus
posterior
pituitary
anterior
tropic hormones = target endocrine glands
hypothalamus
thyroid-stimulating
hormone
(TSH)
Thyroid gland
Adrenal
cortex
posterior antidiuretic
pituitary hormone
(ADH)
anterior
pituitary
gonadotropic
hormones:
folliclestimulating
hormone (FSH)
& luteinizing
hormone (LH)
Kidney
tubules
Muscles
of uterus
Melanocyte
in amphibian
Bone
and muscle
Testes
Ovaries
Mammary
glands
in mammals
Why is there Homology in hormones?
Watch Mr. A’s Video – (#4) Evolutionary Significance of Cell-Cell
communication
What does this tell you about these hormones?
How could these hormones have different effects?
same gene family
gene duplication?
prolactin
mammals
milk
production
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







bone growth
mental development
metabolic use of energy
blood pressure & heart rate
muscle tone
digestion
reproduction
tyrosine
+
iodine
thyroxines
Goiter
Iodine deficiency causes thyroid to enlarge as it
tries to produce thyroxine
+
tyrosine
+
iodine
✗
✗
thyroxines
Endocrine System Control
Feedback
Regulation of Blood Calcium
calcitonin
 kidney
reabsorption
of Ca++
thyroid
Ca++ deposited
in bones
high
blood calcium level
 Ca++ uptake
in intestines
(10 mg/100mL)
low
activated Vitamin D
bones
release Ca++
 kidney
reabsorption
of Ca++
parathyroid
parathyroid hormone (PTH)
Feedback
Female reproductive cycle
egg
matures &
is released
(ovulation)
estrogen
builds up
uterus lining
corpus
luteum
ovary
progesterone
FSH & LH
maintains
uterus lining
pituitary
gland
fertilized egg
(zygote)
hCG
yes
pregnancy
GnRH
hypothalamus
no
corpus luteum breaks down
progesterone drops
menstruation
corpus
luteum
progesterone
maintains
uterus lining
Any Questions??
Robert Wadlow
1918-1940
8' 11"
2009-2010