Interactions in
the Human
Body
Notes and Lab
Your Task
Design and test a model of a negative
feedback system to maintain the
temperature of water in a beaker at
37°C.
Maintaining Equilibrium
• The ability to sense and respond to
conditions or changes in the
environment distinguishes living
organisms from nonliving things.
• The cells of living organisms function
best in a constant, balanced internal
environment.
• Organisms must maintain a “steady
state” called homeostasis to survive.
• Cells, tissues, organs, and organ systems in
an organism must work together to adjust to
changing conditions.
• When humans experience cold temperatures,
they respond by shivering to increase body
temperature by muscle movement.
• In extremely hot temperatures, humans may
respond by sweating to cool off. These
responses automatically occur when body
temperatures rise above or fall below a
human’s normal temperature of 37°C.
Interactions to Maintain
Homeostasis
• To remain in balance, systems must be monitored
and adjusted.
• The temperature feedback system you will make in
the beaker is a model of a negative feedback system
to maintain a constant temperature
• In order for organisms to maintain homeostasis,
every cell, tissue, organ, and organ system in an
organism must work together to adjust to changing
conditions.
• Systems in the human body use negative feedback
systems to maintain a balance of sugar in the blood,
body temperature, heart rate, water content, and
blood flow.
• The nervous and endocrine systems coordinate the
activities of all of the other body systems to maintain
homeostasis and control body responses to
environmental changes
• The nervous system consists of cells called neurons
which are able to sense and help the body respond
to changes in the environment.
• Neurons have the ability to quickly send electrical
messages or impulses to each other.
• Many neurons bundled together make up nerves,
which send messages to the brain.
• The brain, the major control center of the nervous
system, responds to messages sent in from all areas
of the body.
• Have your ever noticed the changes that occur in
your body during exercise or physical education
class?
• Exercise causes an increased need for oxygen.
• The brain detects low levels of oxygen in the blood
and sends signals to increase the heart rate and the
breathing rate.
• Your pulse is a measure of your heart rate.
• Nerves carry messages to parts of the brain that
control involuntary activities, such as heart rate.
• These nerves send messages when blood pressure ,
or the force of blood pushing on the walls of blood
vessels, becomes too high.
• The high blood pressure is sensed, and feedback
mechanism sends a message to the brain to slow
down the heart rate.
Instructions
1.
2.
3.
4.
5.
6.
Under most conditions, normal human body temperature is
maintained at 37°C.
Using the materials provided at the station ,your group must
design a system and procedures to keep 200-300 mL of water
at a constant temperature of 37°C.
Heat 200-300 mL of water to a temperature of 37°C and
maintain that temperature for ten minutes.
Record the temperature readings in the chart in thirty second
intervals.
Construct a graph of the data.
Remember to label the independent variable on the x axis,
the dependent variable on the y axis, and add an appropriate
title.
Time
30 seconds
1 minute
1 minute 30 seconds
2 minutes
2 minutes 30 seconds
3 minutes
3 minutes 30 seconds
4 minutes
4 minutes 30 seconds
5 minutes
5 minutes 30 seconds
6 minutes
6 minutes 30 seconds
7 minutes
7 minutes 30 seconds
8 minutes
8 minutes 30 seconds
9 minutes
9 minutes 30 seconds
10 minutes
Temperature (°C)
Questions
1.
2.
3.
4.
5.
6.
7.
If the temperature of the water went above 37°C, what did
your group do to bring it back to the set point of 37°C?
If the temperature of the water went below 37°C, what did
your group do to bring it back to the set point of 37°C?
Did you notice a pattern in the data? If yes, explain the
pattern.
What are some practical examples of other systems that
regulate temperature to a certain setting?
Which part of the system acts as the thermostat to detect
temperature changes?
Which system in your body has cells that sense changes in
body temperature?
Which systems in your body help to regulate body
temperature?
Blood –The Link to All Body
Systems
• The main task of the cardiovascular system, or
circulatory system, is transportation.
• The cardiovascular system delivers needed materials to
body cells.
• These substances all travel in blood.
• The heart pumps blood through blood vessels that reach
all parts of the body.
• Since every cell in the body depends on the
cardiovascular system to deliver needed materials to
it ad to remove wastes, al body systems interact with
the cardiovascular system.
Interactions in
Transporting Oxygen
• The organ system responsible for
delivering oxygen to your cells is the
respiratory system.
• The respiratory system could not deliver
oxygen to your body cells or remove CO2
without the cardiovascular and muscular
systems.
The Role of the Respiratory
System
• Air enters the body through the nostrils. It
travels to the lungs through a tube called the
trachea.
• The lungs , which are the main organs of the
respiratory system, contain hundreds of round
sacs called alveoli.
• The alveoli are the structures through which
oxygen moves from the air into the blood.
• CO2 moves through alveoli in the opposite
direction: from the blood into the air.
The Role of the Cardiovascular
System
• Each alveolus is surrounded by capillaries.
• Capillaries are the smallest blood vessels in the cardiovascular
system.
• Inside each lung, oxygen in the air moves through the walls of the
alveoli and into the capillaries.
• In the capillaries, the oxygen binds to red blood cells, which are
carried in the bloodstream through the rest of the body.
• As the oxygen rich red blood cells move through the cardiovascular
system, they release the oxygen to body cells.
• As oxygen in the alveoli passes into the bloodstream, CO2 is moving
in the opposite direction.
• CO2 passes from the blood, through the walls of the alveoli, and into
the air inside the alveoli.
• From the alveoli, CO2 leaves your body.
• The CO2 is expelled when you breath out.
• How would
homeostasis be
affected by the
absence of the
organs pictured
on the left?
• What role does the nervous system play in
the proper functioning of the following
systems?
• Skeletal
• Immune
• Muscular
• Endocrine
• Circulatory
• Respiratory
• Digestive