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The Endocrine System
A Regulatory System
The Endocrine System
The Endocrine System
HORMONES ACT ON SPECIFIC CELLS
The Endocrine System
THE BODY ACTIVITIES ARE COORDINATED

Hormones – substances
that are secreted by cells
that act to regulate the
activity of other cells.

Hormones regulate many
processes such as :
growth, development,
behavior and reproduction.
The Endocrine System
THE BODY ACTIVITIES ARE COORDINATED

Endocrine hormones
help coordinate the
production, use &
storage of energy.

Endocrine hormones
help allow us to react
to stimuli from outside
the body.
The Endocrine System
To maintain balance is
to maintain
coordination is to
maintain
homeostasis…
thanks to hormones
http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp27/animations/ch27/1_glucose_regulation.swf Glucose Regulation
The Endocrine System
HORMONES ARE MADE IN CERTAIN ORGANS AND TISSUES

Endocrine Glands – Are
ductless glands in the
body that release their
product(s) directly into
blood stream or the
extracellular fluid
around the outside of
cells.
The Endocrine System
HORMONES ARE MADE IN CERTAIN ORGANS AND TISSUES

The endocrine system is
composed of ductless glands
or other related tissues.

These glands produce
hormones, which are chemical
messengers that are secreted
into the bloodstream or into
extracellular fluid.
The Endocrine System
HORMONES ARE MADE IN CERTAIN ORGANS AND TISSUES

The hormones usually will
end up somewhere else in
the body. Hormones are
used to regulate and
coordinate systems of the
body.
The Endocrine System
Endocrine Disorders
Hypo – a disorder where a gland is not secreting
enough of a hormone.
Hyper – a disorder where a gland is secreting too
much of a hormone.
The Endocrine System
HORMONES ACT ON SPECIFIC
CELLS
Amino - Acid Based Hormones –
are water-soluble hormone made of
amino acids.
Steroid Hormones – fat-soluble
hormone derived cholesterol.
Once hormones are secreted into the
blood or extracellular fluid they are
transported to a target cell(s) where
they will have a desired effect.
http://www.wisc-online.com/objects/index_tj.asp?objid=AP13704 Actions of Hormones
The Endocrine System
HORMONES ACT ON SPECIFIC CELLS
Protein based
hormones bind to a
specific receptor on
the cell membrane of
the target cell.
The Endocrine System
HORMONES ACT ON SPECIFIC CELLS
This binding of the hormone
and membrane receptor
causes a series of internal
changes to occur with in the
target cell.
The Endocrine System
HORMONES ACT ON SPECIFIC CELLS
Examples of changes
include transcription,
exocytosis or
endocytosis, membrane
channels to open or
close.
See textbook Page 986
The Endocrine System
HORMONES ACT ON SPECIFIC CELLS
Steroid hormones
are all derived from
cholesterol, a lipid. It
can diffuse directly
through the cell
membrane, which is
also made up of
lipids.
The Endocrine System
HORMONES ACT ON SPECIFIC CELLS
Steroid hormones
usually combine with
nuclear membrane
receptors. This
produces an
activated hormonereceptor complex.
The Endocrine System
HORMONES ACT ON SPECIFIC CELLS
The receptor hormone
complex will bind
directly to a gene and
causing transcription
of the gene to occur,
leading to the
production of a new
protein.
See textbook Page 980-981
http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp27/animations/ch27/cellular_activity_hormones.swf Cellular
activity of Steroid Hormones
The Endocrine System
THE RELEASE OF HORMONES MUST BE REGULATED
Negative Feedback – mechanism
used in homeostasis to keep
monitored variable within a certain
range. A change in one direction
stimulates two control mechanisms to
counteract further change in the same
direction.
Homeostasis is one of the fundamental characteristics of living things.
It refers to the maintenance of the internal environment within tolerable
limits. All sorts of factors affect the suitability of our body fluids to
sustain life; these include properties like temperature, salinity, acidity,
and the concentrations of nutrients and wastes. Because these
properties affect the chemical reactions that keep us alive, we have
built-in physiological mechanisms to maintain them at desirable levels.
When a change occurs in the body, there are two general ways that the
body can respond. In negative feedback, the body responds in such a
way as to reverse the direction of change. Because this tends to keep
things constant, it allows us to maintain homeostasis. On the other
hand, positive feedback is also possible. This means that if a change
occurs in some variable, the response is to change that variable even
more in the same direction. This has a de-stabilizing effect, so it does
not result in homeostasis. Positive feedback is used in certain
situations where rapid change is desirable.
To illustrate the components involved in negative feedback, we can use
the example of a driver trying to stay near the speed limit. The desired
value of a variable is called the set point. Here, the set point is a speed
of 55 mph; in controlling body temperature, the set point would be 98.6
degrees. The control center is what monitors the variable and
compares it with the set point. Here, the control center is the driver; for
body temperature, it would be the hypothalamus of the brain. If the
variable differs from the set point, the control center uses effectors to
reverse the change. Here, the effector is the foot on the accelerator
pedal; in controlling body temperature, it would include the glands that
sweat and the muscles that shiver.
The Endocrine System
The Endocrine System
The Endocrine System
Malfunctions
Disease
Symptom
Goiter
Enlargement of the thyroid (red round
gland in throat).
Diabetes
Lack of insulin.
The Endocrine System
Nervous System vs. Endocrine
Nervous
Endocrine
Type of Chemical
Message
Neurotransmitters
Hormones
Pathway
Neuron adjacent to other neuron.
Bloodstream
Extacellular fluid outside
of cell
Timing
Quick reaction.
Slow reaction
Short effect not very long lasting
Long lasting
Hormone
Secreted by
Target Tissue
Effects
Follicle Stimulating
Hormone
Pituitary Gland
Ovaries and Testes
Regulates the development of male and
female gametes
Cortisol
Adrenal gland
Liver
Reaction to long term stress; increases blood
glucose levels (energy)
Corticotropin
releasing
hormone
(CRH)
Pituitary Gland
Reaction to stress; tells pituitary gland to
release adrenocorticotropic hormone
(ACTH) which leads to increased blood
glucose
Adrenal gland
Stimulates the release of cortisol and other
steroid hormones from the adrenal cortex
– increases blood glucose
Pituitary gland
Ovaries and Testes
Stimulates the release of egg in females;
stimulates secretion of sex hormones
(testosterone, estrogen and
progesterone)
Prolactin
Pituitary gland
Mammary glands
Stimulates milk production in breasts
Growth Hormone
(GH)
Pituitary gland
All tissues
Stimulates protein synthesis and bone and
muscle growth
Thyroid Stimulating
Hormone
(TSH)
Pituitary gland
Thyroid gland
Antidiuretic
Hormone
(ADH)
Pituitary gland
Kidneys, blood vessels
Adrenocorticotropic hormone
(ACTH)
Luteinizing
Hormone (LH)
Hypothalamus
Pituitary gland
Stimulates the synthesis and release of
thyroid hormone from the thyroid gland
Stimulates reabsorption of water from the
kidney; constricts blood vessels
Hormone
Secreted by
Target Tissue
Effects
Oxytocin
Pituitary gland
Mammary glands,
uterus
Stimulates uterine contractions and milk
production
Calcitonin
Thyroid gland
Bone tissue
Stimulates calcium to be deposited in bone
tissue in order to lower blood calcium levels
Bone tissue; kidney
Stimulates bone cells to break down and
release calcium to blood; stimulates kidneys
to reabsorb calcium from urine; activates
vitamin D which helps absorb calcium in
intestines
Liver, muscle
Increases blood sugar, increases blood
pressure, increases heart rate in response to
stress – fight or flight
Liver, muscle
Decreases blood sugar, decreases blood
pressure, decreases heart rate in response
to no stress – rest and digest
Kindey, sweat glands
Retrieves sodium from fluid filtered in kidney
(urine); increases volume of blood which
increases blood pressure; stimulates kidneys
to get rid of potassium
Insulin
Pancreas
(islets of
langerhans)
Liver
Stimulates liver to build glycogen from
glucose and helps cells take up glucose 
decreases blood glucose
Glucagon
Pancreas
(islets of
langerhans)
Liver
Stimulates liver to break down glycogen to
glucose  increases blood glucose
Parathyroid
Hormone (PTH)
Epinephrine
(adrenaline)
Norepinephrine
(noradrenaline)
Aldosterone
Parathryroid
glands (back of
thyroid)
Adrenal gland
Adrenal gland
Adrenal gland
The Endocrine System
Animations
http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp27/animations/ch27/sodium_and_blood_pressure.swf Sodium and Blood Pressure
http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/an/m4/s2/index.htm Glands and Hormones of the Head and Neck.
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter47/animations.html# Steroid Hormone
http://entochem.tamu.edu/G-Protein/index.html (Honors G- Protein Transduction)
http://www.wisc-online.com/objects/index_tj.asp?objid=AP15004 Gland Overview
http://www.wisc-online.com/objects/index_tj.asp?objid=AP13804 Stress Responce