Download Types of homeostatic controls

Endocrine system
General Infomation
• Connected to the
nervous system via
the Hypothalamus.
• Often in this system,
the sensor and
control center are the
same.
Component 1: Glands
• Endocrine glands release hormones
directly into the blood. (They may release
other secretions, too)
• Master Gland: Pituitary Gland
– Produces “tropic hormones”, which regulate
hormone production
– Anterior section & Posterior section
• Anterior: produces 11 hormones!
• Posterior: stores ADH & oxytocin
Other Glands…
Hormones
I’m stressed.
• Chemical messengers
• Carry instructions to target organs.
• Very potent! Released in small quantities.
I’m hungy.
I’m sleepy.
Two Types of Hormones: Steroid
• Made from cholesterol (hydrophobic)
• In the blood they combine with protein carriers
until they reach the target cell.
• Fat soluble, so they pass through the target cell
membrane easily.
• Once inside, they form a hormone-receptor
complex in the cytoplasm, which enters the
nucleus and activates transcription of specific
gene(s). (see handout)
Two Types of Hormones: NonSteroid
• Made from amino acids (hydrophillic)
• Cannot pass directly through the cell membrane
• Target cells have receptors on their surface for
this type of hormone. When activated, they
trigger a chain of chemical reactions within the
cytoplasm, where ATP is dephosphorylated to
create cyclic AMP, which activates the required
pathway. (see handout)
How The Endocrine System Works
• Two possibilities…
– Antagonistic hormones constantly work
against each other to maintain a constant
environment.
– Hormones that act through negative feedback
will activate one response and inhibit their
own release at the same time.
Flowcharts: Antagonistic
Hormone
Effector(s)
Action
Hormone
Gland,
Component
Effector
Action
Patient!
• Symptoms:
– Fatigue
– Tingling in hands and feet
– Have passed out a few times
– Frequent urination
– Very thirsty
Diabetes
• Canadians Banting & Best discovered that
insulin was responsible for diabetes 
Won Nobel Prize.
• 3 types:
– Type I: Born with an immune system that
attacks pancreatic cells.
– Type II: Cells stop responding to insulin.
Usually due to poor diet and lack of exercise.
– Gestational: Diabetes during pregnancy.
Usually clear up after birth of baby.
The Pancreas: Blood Sugar
• After you’ve eaten, your blood sugar
increases.
– Beta cells in the pancreas release insulin,
which stimulates receptors on the liver cells,
muscle and other organs to store glucose in
the form of glycogen. This lowers blood sugar.
• In between meals, your blood sugar
decreases
– Alpha cells in the pancreas release glucagon,
which stimulates receptors on liver cells,
muscle and other organs to break down
glycogen and release it. This raises blood
sugar.
Questions
• What type of hormone are insulin and
glucagon?
• What type of homeostatic control is
portrayed?
Flowcharts: Negative Feedback
Event
Stimulates
Inhibits
Gland
Releases
Hormone
Stimulates
Gland
Releases
Hormone
Stimulates
Action
Effector
Effector
Action