HOM Lesson 7-Unit3
Unit 3: Homeostasis and immunity
Essential Question: What are feedback mechanisms?
Objective:
Students will understand that feedback mechanism are the ways the body
maintains homeostasis.
Aim:
What are feedback mechanisms?
Assessment:
Completion of worksheet, discussion
Do Now:
In the winter how does your house keep from getting too cold or too
(5 min)
warm?
How do you know if there is a fire in your home?
How do you know when you have a fever?
How do you know when you have little gas in your car?
Mini-Lesson:
Homeostasis is the internal stability that an organism maintains.
(15 min)
An organism’s external and internal environment is always changing
(stimulus)(we go outside when it’s cold, there is less water in the soil
for plants) so its homeostasis is constantly threatened.
Response/feedback mechanism is how the living organism responds
to the stimulus.
If there were no monitoring then there would be no adjustments.
Example: You run and need more oxygen. What is the stimulus and
what is the response? What if your body didn’t deliver the oxygen
faster? You wouldn’t get the oxygen you need and would become
hurt.
Guided Practice:
(15 min)
In humans homeostasis is controlled by the nervous and endocrine
systems.
Vocabulary:
Materials/Supplies
There are two feedbacks: positive and negative. Today we will focus on
negative feedback systems.
Negative feedback systems is when the nervous system is told of
something and sends a message to the endocrine/skeletal ect system to
respond.
Example: Touch something hot, message goes to nerves and brain tells
you to take finger off hot surface.
Running very fast, message goes to your brain to tell your lungs to work
harder.
Students do practice problems
What are some ways that we protect ourselves? Students fill in picture:
Eyes, ears, smell, release hormones that stimulate emergency response,
muscles to fight, skin to keep out foreign organism, tears, saliva, nervous
system for rapid coordination.
How does disease play a role in all of this? Disease is any condition that
HOM Lesson 7-Unit3
prevents the body from working correctly.
What are some diseases that can keep the body from working correctly?
How do these diseases affect the body? More specifically, what body
system is being affected?
How do these diseases come about? (poor nutrition, inherited disorders,
toxins, organ malfunction, high risk behavior)
The immune system is the body’s main defense against foreign invaders.
Antigens detect their presence and antibodies (proteins) attack.
Closing/Wrap Up:
(5 min)
Homework: # 11 feedback mechanism worksheet
HOM Lesson 7-Unit3
Feedback Mechanisms
Practice Problems:
What are the stimulus and the feedback mechanism?
1. During a race a runner’s body temperature increases.
Stimulus:
Feedback Mechanism:
2. A virus enters a plant.
Stimulus:
Feedback Mechanism:
3. A student accidentally puts his hand n the water dragon’s tank and the water dragon bites
him so the student pulls his hand away. The water dragon represents
a. a response b. an impulse c. a stimulus d. an affect
4. When this student pulls his hand away, this represents:
a. a response b. an impulse c. a stimulus d. an affect
5. Body cells need glucose for energy. Glucose in your body reaches above the normal
limits. Your pancreas secrets insulin (a hormone) which tells the glucose to move from
the blood to your body cells.
Stimulus:
Feedback Mechanism:
6. Increased muscle activity is accompanied by an increase in heart and breathing rate.
Stimulus:
Feedback Mechanism:
What would happen if the heart and the breathing rate did not increase to match the
increased muscle activity?
7. Leaves in a plant detect water storage. Specialized cells called guard cells change shape
so that less water will evaporate.
Stimulus:
Feedback Mechanism:
HOM Lesson 7-Unit3
What are some ways that we protect ourselves?
HOM Lesson 7-Unit3
Homework # 11
Name_______________________
1. Some plants respond to light by enlarging their leaf pores. This response is important
because it increases the plant’s intake of:
a. Carbon dioxide
b. oxygen
c. water
d. nitrogen
2. Maintenance of the pH of human blood within a certain range is an example of
a. Negative feedback
b. enzyme action
c. immune response c. backward
feedback
3. Many different feedback mechanisms have evolved over time. These mechanisms allow
an organism to respond to changes in both its internal and external environment. Select
an organism you have learned about and describe how a specific feedback process works
within that organism.
4. When a person is suffering from an infection such a sore throat or chicken pox, his blood
usually shows an increase in
a. Enzymes
b. antibodies c. hormones d. sugars
5. The body makes proteins that attack foreign invaders. These are called:
a. Antibodies
b. vaccines
c. hormones d. antobotics
6. Poisonous chemicals that attack living tissue and causes damage in humans are called:
a. Antibodies
b. viruses
c. antibiotics d. toxins
Read the following and the questions that follow.