Download The Endocrine System

Chemical Regulation
Its function is to regulate metabolism, homeostasis,
growth, sexual development, and reproduction.
The endocrine system
consists of a complex
collection of glands
that produce chemical
messengers called
hormones.
How does the Endocrine System Regulate the Body?
Glands- organs that manufacture and secrete hormones
directly into the bloodstream
Hormone- “chemical messenger”that travel in the blood until
it reaches the target cells. Each hormones fit into its target
cells like a key fits a lock. The hormone causes a reaction in
only the target cell or organ.
How is the endocrine system different from the nervous system?
The endocrine system works with the nervous system to
help regulate and control different bodily functions. The
endocrine system acts more slowly than the nervous
system because hormones are transported by blood while the
nervous system sends electrical signals along nerves that
travel much faster.
The endocrine system is like snail mail…
It works slowly but the effects last a long time…
while the nervous system is like a text or
email…it travels quickly and is done!
Major Glands of the Endocrine System
Major Glands of the Endocrine System
In the brain:
Hypothalamus- controls the release of
pituitary hormones
Pituitary- “Master Gland” that controls
most other endocrine glands. Produces
HGH (human growth hormone), TSH
(thyroid stimulating hormone), FSH
(follicle stimulating hormone) and
several other hormones
Pineal- releases hormones that control
body cycles like melatonin that
controls our sleep cycle (circadian
rhythm)
Major Glands of the Endocrine System
Thyroid- butterfly shaped gland
located in the neck that produces
thyroxin which controls the speed of
metabolism
Parathyroid- located behind the
thyroid gland, controls levels of
calcium and phosphorous in the
body
Thymus- found in the upper chest; controls
the development of a healthy immune
system
Major Glands of the Endocrine System
Pancreas- located behind the
stomach; controls the
production of insulin and
glucagon which control sugar
levels in the blood
Adrenal glands- located above
the kidneys; produces
epinephrine or adrenaline
which increases blood
pressure and heart rate in
times of stress…FIGHT OR
FLIGHT response.
Fight or Flight
The adrenal glands secrete adrenaline and other hormones in response to
stress. Fight or flight response is a protective measure. It provides a burst
of energy through increased heart rate, blood pressure, and respiration.
All of these physical
responses are intended to
help you survive a
dangerous situation by
preparing you to either run
for your life or fight for
your life (thus the term
"fight or flight"). Fear -and the fight-or-flight
response in particular -- is
an instinct that every
animal possesses.
Major Glands of the Endocrine System
Ovaries- located in the pelvis of
females; produce estrogen and
progesterone which control female
sexual characteristics including
menstruation
Testes- located in the
male scrotum; produce
testosterone which
controls male sexual
characteristics including
sperm production
Endocrine System: Negative Feedback Mechanism
Negative feedback is a process that happens when your systems need to slow
down or completely stop a process that is happening.
A good example of a negative feedback
mechanism is a home thermostat (heating
system). The thermostat contains a
thermometer that detects change in
temperature. If the heating system is set
at 67 degrees Fahrenheit and the
temperature drops, the thermometer
senses the drop and the heat is turned on.
Once the temperature reaches 67 degrees
again, the furnace is turned off which
keeps the house at a stable temperature.
Endocrine System: Negative Feedback Mechanism
Negative feedback is a process that happens when human systems need to slow
down or completely stop a process that is happening to maintain homeostasis.
The control of blood sugar (glucose)
by insulin is an example of a
negative feedback mechanism.
When sugar levels rise, receptors in
the body sense a change . In turn,
the pancreas secretes insulin into
the blood effectively lowering blood
sugar levels. Once blood sugar levels
reach homeostasis, the pancreas
stops releasing insulin. If sugar
levels get too low, glucagon is
released to bring sugar out of
storage and back into the blood.
Insulin and glucagon constantly
alternate to maintain homeostasis
for blood sugar levels.