Download The Endocrine System - Highland 4U Biology with Mr. Byrnes

The Endocrine System
or
“Harry Potter and the Sorcerer’s
Hormones”
Chemical Control
• A change in the environment or a malfunction of
one organ affects an entire animal
• However, animals may continue to function
because of compensations made by two control
systems: the nervous system and the endocrine
system
• The nervous system enables the body to adjust
quickly to changes, while the endocrine system
maintains control over a longer period of time
The Endocrine System
• The trillions of cells in your body all interact with
one another. This is coordinated through the
endocrine system of the body
• Works with the nervous system to integrate and
control homeostatic mechanisms
• Composed of glands scattered throughout the
body that secrete chemical signals called
hormones
Endocrine Hormones
• “Chemical signals” or “chemical messengers”
• Secreted by glands directly into the blood stream and
transported by the Circulatory System
• Effects are often slow and long-lasting
• Examples:
– Growth Hormone (GH)
– Insulin
– Epinephrine (adrenaline)
Hormones
• Discovered in 1889 by Joseph von Mering &
Oscar Minkowski (Insulin  dog pancreas
experiment)
• Some glands produce a number of different
hormones, and several hormones may act
together to produce a single effect
• Often very little hormone is needed to
produce an effect in the body
Pituitary Gland – The “Master” Gland
• Exercises control over other endocrine glands, but is
actually controlled itself by the hypothalamus
• Small, sphere-like organ at the base of the brain
• Connected to the
hypothalamus (p376)
• Produces and stores
hormones
Pituitary Gland – The “Master” Gland
• Composed of 2 distinct lobes: the posterior
lobe and the anterior lobe
Pituitary Gland – The “Master” Gland
posterior: stores hormones (ADH & oxytocin)
produced in the hypothalamus, which travel along
specialized nerve cells and are released when
necessary
anterior: stimulated by hormones from the
hypothalamus to produce & release its own
hormones (FSH, LH, TSH, etc.)
*(Figure 6 on pg. 376)
CHALLENGE!!
• The class will be split into 2 groups. Each group will
dramatically demonstrate the actions of the hypothalamus,
pituitary gland, hormones and target cells/organs
• Use cue cards and markers to illustrate which components
of the system each person represents
• Be sure to include details such as what each hormone does
and which component is stimulating which
• Use pg. 375-377 of your textbook to help you
• Mr. Byrnes and Mrs. Wood will judge which group has been
the most successful! You have 5 minutes. GO!!
Hormones: How do they work?
• Hormones do not affect all cells
• Cells must have a receptor for a hormone in
order for that hormone to have any affect!
(Receptors are specific to specific hormones)
• The number of receptors on individual cells
may also vary
Hormones: How do they work?
• There are 2 types of hormones: steroid
hormones and protein hormones
Steroid hormones - made up of cholesterol (lipid)
and so are soluble in fats but not water
– Ex. male & female sex hormones, cortisol
Protein hormones – made up of (surprise!) protein
and so are soluble in water but not fats
– Ex. Insulin and Growth Hormone (GH)
Steroid Hormones (pg. 374)
• Diffuse from the capillaries right through the cell
membrane, and bind to a receptor molecule
• The resulting
hormone-receptor complex
enters the cell nucleus
and binds to DNA
• The hormone activates a
gene that produces
a specific protein
Protein Hormones (pg. 374)
• Combine with receptors on the cell membrane. (Why?)
• Form a hormone-receptor complex that activates an
enzyme called adenylyl cyclase
• Adenylyl cyclase converts ATP to cyclic AMP (cAMP)
• cAMP is a secondary messenger (the hormone itself is the
primary messenger), activating other enzymes in the cell
CHALLENGE!!
• The class will again be split into 2 groups. One group
will act out he method of action of steroid hormones,
the other will act out the method of action of protein
hormones
• Use cue cards and markers to illustrate which
components of the system each person represents
• Be sure to include details about how your category of
hormones works
• Use pg. 374-375 of your textbook to help you
• You have 5 minutes. GO!!