The
Endocrine
System
The Endocrine System
• A system containing many glands that
secrete hormones that send messages in
order to maintain homeostasis
•A group of glands that work together
with the nervous system to coordinate all
body functions.
Glands of the Endocrine System
An Overview of the
functions of the
Endocrine Glands
• Pituitary Gland – the master gland. Called
this b/c it controls all other endocrine
glands and b/c it produces the highest
number of different hormones compared
to all other endocrine glands.
• Hypothalamus – senses the hormone
levels in the blood, then tells the pituitary
what to do with either hormones it
produces or by direct nerve stimulation.
• Pineal Gland – produces a hormone
(melatonin) that helps you go to sleep.
• Thyroid Gland – produces hormones that
influence metabolic rate, decrease blood
calcium and increase bone calcium levels.
• Parathyroid Glands – produces a hormone
that increases blood and decreases bone
calcium levels.
• Thymus Gland – produces a hormone that
stimulates the immune response in children.
• Adrenal Glands – produces hormones help
prepare the body for stress and control
blood pressure.
• Pancreas – produces hormones that
control BSL (blood sugar level).
• Ovaries – produces hormones that control
female characteristics and menstrual cycle.
• Testes – produces a hormone that control
male characteristics and sperm
production.
The Endocrine System
Endocrine gland:
• a group of cells organized into a
ductless gland (no tubes) that secretes
molecular messengers (hormones)
directly into the bloodstream.
Examples: pituitary, adrenal and thyroid
Sketch the diagram in your notes
Basic Structure of an endocrine gland:
Exocrine gland:
• a gland that dumps molecules (ex. enzymes
or tears - not hormones) into ducts that
generally lead out of the body or into
another organ. It is a ducted gland (has
tubes).
Exocrine glands are NOT part of the
endocrine system
Examples: salivary, milk, and sweat glands
Sketch the diagram in your notes
Basic Structure of an exocrine gland:
Endocrine Glands vs. Exocrine Glands
Endocrine Gland
Exocrine Gland
The Pancreas
• The pancreas is a gland that is part
endocrine and part exocrine.
• The endocrine part of the pancreas
secretes hormones.
• The exocrine part of the pancreas
secretes digestive juices including
enzymes.
Hormone
• A chemical that acts like a messenger;
a protein or steroid that causes a
response in a target cell or organ
• Produced by endocrine glands, NOT
exocrine glands.
Examples: ADH (Antidiuretic hormone),
testosterone, thyroxin
Target Cell
• A cell that a hormone is specifically
directed towards.
Example: ADH works on the collecting
tube in the nephron.
• Target cells contain molecules on their
surface called receptors, to which
hormones can bind. Target cells do their
job when hormones are bound to their
receptors.
Target Cells
• In order for a hormone to cause a
response, its’ shape must match the
shape of its’ target cell’s receptors.
• If the hormone and the cell’s receptors
do not match, the cell will not be
affected and no response by the cell
will occur.
• It’s like the lock and key model
Target Cells
• Example:
http://www.ftmguide.org/images/receptors.gif
Master Gland
• The hypothalamus and pituitary gland in the
brain both work together to control all
secretions by all endocrine glands.
• The pituitary is called the “MASTER GLAND”
because it is near the top of the chain of
command, telling other glands what to do, and
because it produces a large number of different
hormones
• The endocrine glands are essential in helping
the body to maintain Homeostasis.
Chain
of
Command
Assignment
Complete the Compare and
Contrast chart on Endocrine vs.
Exocrine Glands
Master Chart
Gland
Hormone
Hypothalamus
A. Various RF’s
B. Oxytocin
C.
Pituitary Gland
Target Site
Effect Produced