Look Mama, It’s Alive!
Human Feedback Systems
TAKS Objective 2 – The
student will demonstrate
an understanding of
living systems and the
environment
Interdependence occurs
among living systems
TEKS 8.6
The student knows that
interdependence occurs
among living systems. The
student is expected to
identify feedback
mechanisms that maintain
equilibrium or systems such
as body temperature, turgor
pressure, and chemical
reactions
Lesson Objectives
The learner will produce a graph or sketch to
describe a negative feedback system, such as
for serotonin production.
The learner will demonstrate understanding of
how blood glucose is controlled in humans by
creating labeled drawings and providing a
summary of the process.
The learner will produce a labeled sketch that
describes thermal regulation in humans.
Question
True or False: Each body
system works in isolation
Body systems are interrelated
and work through a series of
feedback systems
Question
True or False: Feedback
systems react quickly
In feedback systems, the
action of a system
components is typically slow
in terms of time. That is, there
is a build up in one direction
and slowly, the body returns
to homeostasis.
Prior Knowledge
Identify human systems
and their function
Background
Negative feedback
systems – homeostasis
•
•
•
•
Control of blood glucose
Control blood calcium
Control of blood pressure
Control of body temperature
Negative feedback
Returns the body to equilibrium. It works
like driving car down the road. Constant
adjustment to the right or left is required
to keep the car on the road.
A negative feedback
system is one that tries to
keep the body constant.
In a positive feedback
system the change will
continue to increase in
one direction until
something happens in the
body to stop it.
An example of positive
feedback is
childbirth
The feedback cycle
Glucose: Insulin and Glucagon
The receptors of the pancreas are
responsible for monitoring glucose levels
in the blood.
Blood Glucose Level
• Pancreatic Hormones regulate blood sugar
level before and after meals.
• Islets; clusters of cells in pancreas
– Alphasecrete GLUCAGON – increases sugar
– Beta secrete INSULIN – decreases sugar
What Happens?
• Between meals
Blood glucose lowPancreas secretes
glucagonLiver changes glycogen to
glucoseglucose sent to target tissues
• After a meal
Blood glucose highPancreas secretes
insulinGlucose goes to the Liver(Glygogen)
and goes to Target tissues
Fight or Flight
In emergencies, adrenaline is released by
the body to override the homeostatic
control of glucose. This is done to
promote the breakdown of glycogen into
glucose to be used in the emergency.
These emergencies are often known as
'fight or flight reactions'.
Fight or Flight
Adrenaline is secreted by the adrenal
glands. The secretion of it leads to
increased metabolism, breathing and
heart rate. Once the emergency is over,
and adrenaline levels drop, the
homeostatic controls are once again back
in place
Thermoregulation
ENGAGE
View the video clip, “The Search
for Answers” beginning at 2:50.
The Search for Answers
EXPLORE
Compare the level of serotonin and
serontonin receptors. Stop the video
at 3:50, 3:56, and 4:03
EXPLAIN
1. What is the role of serotonin?
2. What is the effect of high levels
of serotonin on the body?
3. Explain how the body attempts to
regulate serotonin levels?
4. Relate serotonin regulation to
anorexia nervosa.
ELABORATE
Role Play: The Rise and Fall of
Glucose
ELABORATE
How does the body keep from
overheating?
How does the body keep warm?
EVALUATE
1. Produce a sketch or graph and
describe a negative feedback
system.
2. Produce a labeled sketch of
thermal regulation in humans.
3. Summarize the regulation of blood
glucose
Concept Map
The Endocrine
System
regulates
Metabolism
Calcium
and glucose
levels
Response
to stress
by means
of the
by means
of the
by means
of the
by means
of the
Testes
Thyroid
Growth
Water
balance
Reproduction
by means
of the
by means
of the
Pituitary
Ovaries
Pancreas
Parathyroids
Adrenals