Download The Endocrine System and Feedback Loops

The Endocrine System
and Feedback Loops
LSHS Science Department
CA Biology Standard 9c
KM/ rev YM
CA Standard 9c
Students know how feedback
loops in the nervous system
and endocrine systems
regulate conditions in the body.
Body System Review
Nervous System: Recognizes and
coordinates the body’s response to the
internal and external environment.
ex Brain, spinal cord, nerves
Circulatory System: Moves blood
containing oxygen, waste, nutrients and
hormones throughout the body.
ex Heart, blood vessels (veins, arteries, capillaries),
and blood
What is the Endocrine System?
Endocrine System
•
is made up of glands that release their products into the
bloodstream. These products deliver messages throughout
the body.
Function:
•
Controls growth, development and metabolism….maintains
homeostasis!
What organs make up the system?
•
Glands – Specialized organs that produce and secretes
hormones
What are hormones?
•
•
Chemical messengers that alter the activities of cells in
other parts of the body
Hormones do this by binding target cells (cells that have
receptors for a particular hormone)
Glands and Hormones
A.
Pituitary Gland—the “Master” gland
•
•
B.
Pancreas
•
C.
Reproduction
Testes (male)
•
F.
Produces adrenalin (epinephrine) to evoke
“fight or flight” response
Ovaries (female)
•
E.
Produces insulin and glucagon to help
regulate blood sugar levels
Adrenal Gland
•
D.
Recognizes info and regulates endocrine
system
Hypothalamus (above pituitary): Helps
control pituitary gland
Reproduction
Thyroid Gland
•
Regulates metabolism
Sweat Glands?
**not endocrine glands**
F.
What is a Feedback Loop?
Feedback loops are how the nervous
system guides the endocrine system to
control body conditions.
• Nervous system senses the condition
• Endocrine system secretes the hormone to
•
adapt to the condition
Circulatory system carries the hormones to
the target cells where they are needed!
The Organs
Hormones
Alters Cell
Activities
What is a Feedback Loop?
Feedback loops are how the nervous
system guides the endocrine system to
control body conditions.
• Nervous system senses the condition
• Endocrine system secretes the hormone to
•
adapt to the condition
Circulatory system carries the hormones to
the target cells where they are needed!
Negative Feedback
The amount of a
hormone present and
the effect of the
hormone are opposite!
They negatively affect each
other
Ex Blood Sugar Levels
Negative Feedback Loops:
Regulation of Blood Sugar
Insulin and Glucagon help to keep the
level of glucose in the blood stable.
Insulin is secreted when high levels of
sugar are detected (ex after eating)
Glucagon is secreted when low levels of
sugar are detected (ex after exercising)
Hormone:
Insulin
Eat Food
HIGH Blood Sugar
Pancreas—Insulin is secreted
Insulin stimulates cells in the
liver and muscles to absorb
sugar from the blood and store
it as glycogen or fat.
Blood Sugar DECREASES
Pancreas—Insulin stops
Hormone:
Glucagon
Heavy Exercise
LOW Blood Sugar
Pancreas—Glucagon is
secreted
Glucagon stimulates the liver
to break down glycogen and
release glucose back into the
blood. It also stimulates the
release of fatty acids from
stored fats.
Blood Sugar INCREASES
Pancreas—Glucagon stops
Positive Feedback
The more stimulation a gland receives the
more hormone is produced.
• Example:
Breast Feeding and Oxytocin
• When a mother feeds the baby glands in the breast
are stimulated.
• Nervous system signals glands to secrete oxytocin.
• Oxytocin is a hormone that helps the mother produce
more milk.
↑ stimulation = ↑ oxytocin released = ↑ milk production
How does feedback work?
“Like a Thermostat!!!”
Set at a certain temperature
When the temperature in the room changes
the thermostat triggers a heater or
air conditioning system
The heater or air conditioning system adjusts
to the temperature in the room
When the thermostat senses that the room has
reached the appropriate temperature, the
heater or air conditioner turns off.
THIS IS AN EXAMPLE OF A FEEDBACK SYSTEM
The thermostat sends feedback to the heater and air conditioner
Feedback Systems
In humans the hypothalamus acts like
the thermostat of feedback systems and
the endocrine glands act like the heater
or air conditioner.
Hormones are released or stop being
released in response to the messages
sent from the hypothalamus.