Endocrine System
Examples include
Homeostasis is a process that allows a constant internal
Body temperature (37oC),
environment to be maintained despite changes in the external Blood glucose
environment. Electrolytes (Cl-, Na+, K+)
Homeostasis Analogy Blood gasses (O2 & CO2))
For your internal environment to remain constant you must have a
1. Monitor to detect the problem
2. Control to fix it
This is like the thermostat in a house.
If room temperature is set to 21oC, then the
thermostat continuously checks to see if the
temperature has gone down.
If the temperature drops below 21oC, then the
thermostat turns on the furnace, which blows hot air
into the house, heating it. Once the temperature is
above 21oC, then the furnace is shut off.
The role of the hypothalamus is to connect
the endocrine system with the nervous system. Its
main job is to tell the pituitary gland to start or stop
making hormones.
While all cells are exposed to hormones circulating in
the bloodstream, not all cells react. Only
a hormone's "target" cells, which have receptors for
that hormone, will respond to its signal. When
the hormone binds to its receptor, it causes a
biological response within the cell.
Our body has “set points” for each chemical
produced that controls metabolic reactions.
Hormones are maintained at certain levels.
Dynamic Equilibrium = Homeostasis
, 1. ___________________________________
2. ___________________________________
3. ___________________________________
4. ___________________________________
5. ___________________________________
6. ___________________________________
7. ___________________________________
8. ___________________________________
9. ___________________________________
10. ___________________________________
* Are not endocrine glands, but are target
tissue for hormones.
Pancreas - Glucose Regulation
Insulin and glucagon are produced by the Islets of Langerhans cells in the pancreas.
Insulin Insulin is antagonistic to Glucagon → Glucose is gone!
Target: liver, muscles and all other cells Target: liver
• released after a meal to lower glucose levels in the released after fasting to raise glucose levels in
blood the blood
• Increases all cells’ permeability to glucose Glycogen converted to glucose in the liver and
• Glucose stored as glycogen in liver and muscle cells released into the blood.
High blood sugar following a meal Low blood sugar following fasting
Pancreas (Islet cells) Pancreas (Islet cells)
Liver, muscles and all cells Liver
Convert glucose to glycogen in liver and
Convert glycogen to glucose to in liver
muscles. Glucose taken into cells for energy.
Examples include
Homeostasis is a process that allows a constant internal
Body temperature (37oC),
environment to be maintained despite changes in the external Blood glucose
environment. Electrolytes (Cl-, Na+, K+)
Homeostasis Analogy Blood gasses (O2 & CO2))
For your internal environment to remain constant you must have a
1. Monitor to detect the problem
2. Control to fix it
This is like the thermostat in a house.
If room temperature is set to 21oC, then the
thermostat continuously checks to see if the
temperature has gone down.
If the temperature drops below 21oC, then the
thermostat turns on the furnace, which blows hot air
into the house, heating it. Once the temperature is
above 21oC, then the furnace is shut off.
The role of the hypothalamus is to connect
the endocrine system with the nervous system. Its
main job is to tell the pituitary gland to start or stop
making hormones.
While all cells are exposed to hormones circulating in
the bloodstream, not all cells react. Only
a hormone's "target" cells, which have receptors for
that hormone, will respond to its signal. When
the hormone binds to its receptor, it causes a
biological response within the cell.
Our body has “set points” for each chemical
produced that controls metabolic reactions.
Hormones are maintained at certain levels.
Dynamic Equilibrium = Homeostasis
, 1. ___________________________________
2. ___________________________________
3. ___________________________________
4. ___________________________________
5. ___________________________________
6. ___________________________________
7. ___________________________________
8. ___________________________________
9. ___________________________________
10. ___________________________________
* Are not endocrine glands, but are target
tissue for hormones.
Pancreas - Glucose Regulation
Insulin and glucagon are produced by the Islets of Langerhans cells in the pancreas.
Insulin Insulin is antagonistic to Glucagon → Glucose is gone!
Target: liver, muscles and all other cells Target: liver
• released after a meal to lower glucose levels in the released after fasting to raise glucose levels in
blood the blood
• Increases all cells’ permeability to glucose Glycogen converted to glucose in the liver and
• Glucose stored as glycogen in liver and muscle cells released into the blood.
High blood sugar following a meal Low blood sugar following fasting
Pancreas (Islet cells) Pancreas (Islet cells)
Liver, muscles and all cells Liver
Convert glucose to glycogen in liver and
Convert glycogen to glucose to in liver
muscles. Glucose taken into cells for energy.
