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Endocrine System
Hormones
Reproduction
AP Biology
2006-2007
Hormones

Why are hormones needed?
chemical messages from one body part
to cells in other parts of body
 communication needed
to coordinate whole body
 maintaining homeostasis






energy production
growth
development
maturation
reproduction
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growth hormones
Endocrine System

Endocrine system releases hormones

glands which secrete
chemical signals into blood
chemicals cause changes
in other parts of body
 slow, long-lasting response

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 growth hormones
 sex hormones
 response hormones
 metabolism hormones
 and more….
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
Body Regulation

Nervous system &
Endocrine system work
together

hypothalamus



“master nerve control center”
receives information from
nerves around body about
internal conditions
communicates with
pituitary gland


“master gland”
releases many hormones
hormones
 sexual development, growth,
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milk production, pain-relief
hormones
Negative Feedback

Response to changed body condition
every time body is high or low from
normal level a signal tells the body to
make changes that will bring body back to
normal level
hormone 1
 once body is back
to normal level,
lowers
gland
signal is
body condition
turned off

high
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specific body condition
Feedback
Maintaining homeostasis
hormone 1
lowers
body condition
gland
high
specific body condition
low
raises
body condition
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gland
hormone 2
Dynamic Equilibrium and Feedback
Loops
Two Hormones Working in Opposite
Feed Back Loop
Ways to Regulate a “set point”
One Hormone “feeds-back” to
Regulate another Hormone or
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Biology
Product
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
(90mg/100ml)
low
triggers
hunger
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liver
releases
sugar
liver
pancreas
glucagon
reduces
appetite
Let’s Review ??
AP Biology
2006-2007
What do they do?

Maintain homeostasis
blood sugar level
 temperature control


Start a new process
growth
 fetal development
 sexual development

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Body Temperature
Negative Feedback

Negative feedback

every time body is
high or low from
normal level a signal
tells the body to
make changes that
will bring body back


body temperature
control of blood sugar
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Sex & Growth Hormones

Large scale body
changes

how do they work


turn genes on
start new processes
in the body by
turning genes on
that were lying
“dormant”
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Responding to hormones

Lock and key system

hormone fits receptor on “target” cell
target
cell
secreting
cell
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can’t
read
signal
nontarget
cells
can’t
read
signal
Hormone Action at Target Cells
One Messenger
Protein Hormone
Two Messengers
Steroid
Hormone
Nonsteroid hormone
(first messenger)
Receptor
Target cell
membrane
Target cell
membrane
Receptor
Altered
cellular
function
Hormonereceptor
complex
Nucleus
DNA
cAMP
(second
messenger)
Enzyme
activities
Altered
cellular
function
Protein
synthesis
Nucleus
Cytoplasm
Cytoplasm
mRNA
Steroid hormones
Act Directly on DNA
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Protein Hormones affect
Enzyme Activities and Cell Function
Glands

Pineal

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Pituitary


insulin, glucagon
Ovary

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adrenaline
Pancreas

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thyroxine
Adrenal


many hormones:
master gland
Thyroid


melatonin
estrogen
Testes

testosterone
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Pituitary gland hormones

Sex & reproductive hormones

FSH

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
LH
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
luteinizing hormone
stimulates ovaries & testes
prepares uterus for fertilized egg
oxytocin



follicle stimulating hormone
stimulates egg & sperm production
stimulates childbirth contractions
releases milk in nursing mothers
prolactin

milk production in nursing mothers
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hormones
hormones
Reproductive hormones

Testosterone



from testes
sperm
production &
secondary sexual
characteristics
Estrogen


from ovaries
egg production,
preparing uterus
for fertilized egg
& secondary
sexual
characteristics
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Male
reproductive
system

Sperm production
over 100 million produced per day!
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Biology
~2.5 million released per drop!

seminiferous
tubule
sperm
spermatocytes
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Main Functions of Male Repro System
1.
Sperm production
in paired testes

Flagellum
Requires lower
temperature

Scrotum
adaptation for
max. sperm
production
2. Delivery of Sperm
into Female’s
Reproductive Tract
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Mitochondria
Head
Nucleus
Male reproductive system

Testes & epididymis


sperm production &
maturation
Glands
seminal vesicles,
prostate,
bulbourethal
 produce seminal
fluid


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nutrient-rich
Male reproductive system

Testicles

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Scrotum

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where sperm mature
Vas deferens

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sac that holds testicles outside of body
Epididymis


produces sperm & hormones
tubes for sperm to travel from testes to penis
Prostate, seminal vesicles,
Cowper’s (bulbourethal) glands

nutrient rich fluid to feed & protect sperm
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Female reproductive system
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Female reproductive system

Ovaries


Uterus

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tubes for eggs to travel from ovaries to uterus
Cervix

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nurtures fetus; lining builds up each month
Fallopian tubes

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produces eggs & hormones
opening to uterus, dilates 10 cm for birthing baby
Vagina

birth canal for birthing baby
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Female reproductive system
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Egg maturation in ovary
releases
progesterone
maintains
uterus
lining
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produces estrogen
LH
Menstrual cycle

Controlled by
interaction of
4 hormones egg development
FSH & LH
 estrogen
 progesterone
FSH
ovulation = egg release

corpus luteum
estrogen
progesterone
lining of uterus
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days 0
7
14
21
28
Menstrual Cycle Summary Chart
1. Follicle Stage
•
•
•
•
•
Low Estrogen +
progesterone
allows FSH to be
released again
from pituitary
↑FSH
Follicle develops
Follicle produces Estrogen
Egg Matures
Estrogen Thickens Uterus
lining
4. Menstruation
•Sudden decrease in
estrogen and progesterone
•Shedding of Uterine Lining
Corpus luteum
Degenerates
Causing
Progesterone
+ estrogen to
Drop
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Lasts 10-14 days
Lasts 10-12 days
3. Corpus Luteum Stage
• Ruptured follicle becomes the
Day 14
2. Ovulation
•↑ LH released
•Mature egg released
Ovulation
Corpus
Luteum (yellow Body)
• Corpus luteum produces Progesterone
• Uterus lining becomes thicker, prepares
For possible fertilization
Human Menstrual Cycle
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Female hormones

FSH & LH




Estrogen




released from pituitary
stimulates egg development & hormone release
peak release = release of egg (ovulation)
released from ovary cells around developing egg
stimulates growth of lining of uterus
decreasing levels causes menstruation
Progesterone
released from “corpus luteum” in ovaries
 cells that used to take care of developing egg
 stimulates blood supply to lining of uterus
 decreasing levels causes menstruation
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
Fertilization
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Fertilization
Occurs In the Fallopian Tubes
Fallopian tube
Day 4
4 cells
Morula
Day 7
Blastocyst
2 cells
Fertilization
Zygote
Day 0
Implantation of blastocyst
Uterine
wall
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ovary
Egg released
“ovulation”
Early Embryonic Development
All divisions of
A zygote after
Fertilization are
Mitotic cell
divisions
Called Cleavage

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The Three Germ Layers
Differentiation of Cells
Endoderm:
Lining of Digestive
And Respiratory tracts,
Liver and Pancreas
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Mesoderm:
Muscles and Skeleton,
Circulatory and
Reproductive systems
Ectoderm:
Nervous System
Epidermis of skin
Multiple Births

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
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Fertilization is the fusion of a sperm and an egg to form a
zygote, the single cell from which all cells of the human body
are derived. When an egg is fertilized, the remarkable
process of human development begins.
1.If two eggs are released during ovulation, each can be
fertilized by a sperm. What do you think would be the result?
Explain your answer.
2.If one zygote splits into two, each can continue
development on its own. What do you think would be the
result? Explain your answer.
3.Triplets are three babies born at the same time.
Describe three ways that triplets could develop.
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Human Embryo: 3-8 weeks Gestation

Note, the period from week 12 to week 38
is considered Fetal Development
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Fetus to Baby
In spite of the placental “barrier”
Small molecules and
Viruses can still cross
And affect the baby

HIV
Measles
Chicken Pox
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Alcohol (FAS)
Carbon Monoxide (Smoking) Antibodies
Narcotics (Heroine, Crack) Rh incompatibility
It’s All About
HORMONES
Got Questions ?
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Actions of Insulin and Glucagon
Following a Meal
Regulation of
Blood Sugar
Levels to
Maintain
Homeostasis
Beta cells release
insulin into the
blood
Blood
glucose level
increases
Body cells
absorb
glucose
Liver converts
glucose in to
glycogen
Blood
glucose level
decreases
Homeostasis: Normal blood
glucose level
Blood
glucose level
increases
Liver converts
glycogen to
glucose
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Blood
glucose level
decreases
Alpha cells
release glucagon
into blood
Missed a Meal
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
uterus lining
Homeostasis
.
biological processes which keep temperature & other body
variables within a certain range
•For example, temperature, weight, hydration (fluids; H2O)
content of blood (acidity, oxygen, fat, glucose)
Homeostasis is maintained by both (1) internal biological
processes and (2) external behaviors.
Set Point: homeostasis relies upon set points for each
body variable, that is, a specific narrow range of
acceptable values which the body must maintain. For
example, the human body temperature generally stay
between roughly 36.5 and 37.5 degrees Celsius (97.7 and
99.5 degrees Fahrenheit)
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The Thyroid
Gland
•Location: found in the neck, just below the larynx and
in front of the trachea
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Thyroxine
• Iodine-containing hormone
secreted by the thyroid gland
• Regulates rate of metabolism in body
•Increases rate of protein, carbohydrate, and fat
metabolism
•Increases rate of cellular respiration
•Necessary for normal mental and physical
development
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Thyroxine Factory
hypothalamus
TSH-releasing
factor stimulates
Low-level
stimulates
High-level
inhibits
FEED BACK
LOOP
thyroxine
anterior
pituitary
TSH stimulates
RELEASES
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thyroid