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AP Biology
Endocrine System
Hormones
& Homeostasis
Regents Biology
Homeostasis
Homeostasis
maintaining internal balance in the body
organism must keep internal conditions
stable even if environment changes
also called “dynamic equilibrium”
example: body temperature
humans:
too cold = shiver
too warm = sweat
lizard:
too cold = bask in sun
too warm = hide in shade
Regents Biology
Regulation
How we maintain homeostasis
nervous system
nerve signals control body functions
endocrine system
hormones
chemical signals control body functions
Regents Biology
Controlling Body Temperature
high
low
nerve signals
sweat
nerve signals
brain
body temperature
shiver brain
dilates surfaceblood vessels
constricts surfaceblood vessels
Nervous System Control Feedback
Regents Biology
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
growth hormones
Regents Biology
Endocrine System
Endocrine system releases hormones
glands which secrete (release)
chemical signals into blood
chemicals cause changes
in other parts of body
growth hormones
sex hormones
response hormones
metabolism hormones
and more….
Regents Biology
Responding to hormones
Lock and key system
hormone fits receptor on “target” cell
targetcell
non-targetcells
secretingcell
can’tread
signal
can’tread
signal
Regents Biology
Glands Pineal
melatonin
Pituitary
many hormones: master gland
Thyroid
thyroxine
Adrenal
adrenaline
Pancreas
insulin, glucagon
Ovary
estrogen
Testes
testosterone
Regents Biology
Maintaining homeostasis
high
low
hormone 1
lowersbody condition
hormone 2
gland
specific body condition
raisesbody condition
gland
Feedback
Regents Biology
Negative Feedback
Response to changed body condition
if body is high or low from normal level
signal tells body to make changes that will
bring body back to normal level
once body is back
to normal level,
signal is
turned off
high
hormone 1
lowersbody condition
gland
specific body condition
Regents Biology
liver
pancreas
liver
Regulation of Blood Sugar
blood sugar level(90mg/100ml)
insulin
body cells takeup sugar
from blood
liver storessugar
reducesappetite
glucagon
pancreas
liver releases
sugartriggershunger
high
low
FeedbackEndocrine System Control
AP Biology 2006-2007
Everyone’s doing it, so
Ask Questions!!
Regents Biology
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”
Regents Biology
Pituitary gland hormones
Sex & reproductive hormones
FSH
follicle stimulating hormone
stimulates egg & sperm production
LH
luteinizing hormone
stimulates ovaries & testes
prepares uterus for fertilized egg
oxytocin
stimulates childbirth contractions
releases milk in nursing mothers
prolactin
milk production in nursing mothers
hormones hormones
Regents Biology
Reproductive hormones Testosterone
from testes
sperm production & secondary sexual characteristics
Estrogen from ovaries
egg production, preparing uterus for fertilized egg & secondary sexual characteristics
Regents Biology
Sperm production
over 100 million produced per day!
~2.5 million released per drop!
Male
reproductive
system
Regents Biology
spermatocytes
seminiferous
tubule
sperm
Regents Biology
Male reproductive system
Testes & epididymis
sperm production & maturation
Glands
seminal vesicles, prostate, bulbourethal
produce seminal fluid nutrient-rich
Regents Biology
Male reproductive system
Testicles
produces sperm & hormones
Scrotum
sac that holds testicles outside of body
Epididymis
where sperm mature
Vas deferens
tubes for sperm to travel from testes to penis
Prostate, seminal vesicles,
Cowper’s (bulbourethal) glands
nutrient rich fluid to feed & protect sperm
Regents Biology
Female reproductive system
Regents Biology
Female reproductive system
Ovaries
produces eggs & hormones
Uterus
nurtures fetus; lining builds up each month
Fallopian tubes
tubes for eggs to travel from ovaries to uterus
Cervix
opening to uterus, dilates 10 cm for birthing baby
Vagina
birth canal for birthing baby
Regents Biology
Female reproductive system
Regents Biology
Egg maturation in ovary
releasesprogesterone
maintainsuteruslining
produces estrogen
Regents Biology
LH
FSH
estrogen
progesterone
lining of uterus
egg developmentovulation = egg release
corpus luteum
0 7 14 21 28days
Menstrual cycle
Controlled by
interaction of
4 hormones
FSH & LH
estrogen
progesterone
Regents Biology
corpusluteumovary
Female reproductive cycle
pregnancy
maintainsuterus lining
no
yes
Feedback
estrogenegg
matures &is released(ovulation)
builds up uterus lining
FSH & LH
progesterone
progesterone
fertilized egg(zygote)
HCG
corpus luteum breaks downprogesterone drops
menstruation
corpusluteum
maintainsuterus lining
GnRH
pituitarygland
hypothalamus
Regents Biology
Female hormones FSH & LH
released from pituitary
stimulates egg development & hormone release
peak release = release of egg (ovulation)
Estrogen
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
Regents Biology
Fertilization
AP Biology
Any Questions??
Regents Biology
What do they do?
Maintain homeostasis
blood sugar level
temperature control
Start a new process
growth
fetal development
sexual development
Body Temperature
Regents Biology
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
Regents Biology
Regulation by chemical messengers
axon
endocrine gland
receptor proteins
target cell
Neurotransmitters released by neurons
Hormones release by endocrine glands
receptor proteins
hormone carried by blood
neurotransmitter
Regents Biology
Body Regulation
hormones hormones
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
sexual development, growth,
milk production, pain-relief
Regents Biology
What hormones are secreted by the
thyroid gland?
T4 (thyroxine)
T3 (tri-iodothyronine)
Regents Biology
Hypothalamus
Anterior
pituitary
Thyroid
TRH
TSH
T3 T4
Regents Biology
Hyperthyroidism
Caused by thyrotoxicosis (high T3T4)
Signs and symptoms link to HIGH
metabolic rate
Weight and muscle loss
Increased appetite
Heat intolerance and sweating
Anxiety/irritability
Regents Biology
Grave’s Disease
Autoimmune disease
Body’s immune system produces
Thyroid Stimulating Antibodies that
act on the thyroid to increase T3/T4.
Exopthalmos
Regents Biology
Hypothalamus
Anterior
pituitary
Thyroid
TRH
TSH
T3 T4
High T3T4 levels
result in inhibition
of TSH and TRH
Regents Biology
Hypothyroidism
Low T3/T4
Signs and symptoms relate to a lowered
metabolic rate
Weight gain
Lethargy
Alopecia
Sensitive to cold
Slow movements
Regents Biology
Causes of hypothyroidism
Autoimmune disease: Hashimoto’s Disease
Iodine deficiency
Previous surgery/treatment that have damaged the thyroid
Radioactive iodine therapy
Thyroidectomy
Regents Biology
Goitre
Enlarged thyroid gland
Causes:
Tumour
Graves disease
Hashimoto’s disease
Iodine deficiency
Will result in hypothyroidism