1. AIM: What strategies do organisms use to maintain homeostasis?
November 24, 2014
AIM: What strategies do organisms use to maintain homeostasis?
Do Now: How do we keep the inside of our homes at a stable temperature, even when it is hot or cold outside? BE SPECIFIC!
Take out homework

2. Homeostasis
Homeostasis = stability and balance inside of our bodies, even when our outside environment is unstable, and changes a lot
Example: Temperature Homeostasis
How do we do this in our homes?

3. Temperature “Homeostasis” in our Homes
Set point = the desired, stable room temperature
When the room temperature is at the set point, HOMEOSTASIS has been reached.
How do we do this in our bodies?

4. Temperature “Homeostasis” in our Bodies
Our bodies maintain homeostasis using
NEGATIVE FEEDBACK.
Negative feedback is the body’s REACTION to an external change.
It is “negative” because it OPPOSES (goes against, or opposite) the external change.

5. Temperature “Homeostasis” in our Bodies
Normal body temperature: 98.6F
It’s hot outside!
It’s cold outside!
Negative Feedback Loop:
Body begins to heat up
Body cools back down
Body begins to cool
Body heats back up
Brain detects higher temperatures and sends signal to sweat glands
Brain detects lower temperatures and sends signal to muscles
Sweat glands release sweat
Muscles shiver

6. Types of Homeostasis: Temperature homeostasis Nutrient homeostasis
Blood oxygen level homeostasis
- exercise
Water level homeostasis
the kidneys!
Blood sugar level homeostasis
- diabetes

7. Body Systems work to maintain Homeostasis

8. Article: Prader-Willi Syndrome
How does Prader-Willi syndrome affect homeostasis?
Discussion Questions
What is the body’s normal response to eating?
How is this an example of negative feedback?
What is wrong with Prader-Willi patients?

9. Eating and Negative Feedback
What could be wrong with Prader-Willi patients?
Normal stomach fullness and nutrient levels
You haven’t eaten in awhile
Stomach is empty
Stomach is full
The brain stimulates feelings of hunger, causing us to eat.
Stomach cells detect the lack of food, and send chemical signal (ghrelin) to the brain.

10. EXIT TICKET
Relate this image on how our bodies maintain homeostasis (BALANCE).

11. 2 - Hypertension

12. Which body system is malfunctioning?1 2 3 4 5 6 7 8 9

13. 3) Asthma

14. Which body system is malfunctioning?1 2 3 4 5 6 7 8 9

15. 4) Diabetes

16. Which body system is malfunctioning?1 2 3 4 5 6 7 8 9

17. 5) Lactose Intolerance

18. Which body system is malfunctioning?1 2 3 4 5 6 7 8 9

19. 6) Kidney Stones

20. Which body system is malfunctioning?1 2 3 4 5 6 7 8 9

21. Scientific Synthesis
Describe how our bodies use negative feedback to maintain homeostasis. In your answer, be sure to include:
the definition of homeostasis
the different levels of organization of the human body that work to maintain homeostasis
the definition of negative feedback, and how negative feedback helps to maintain homeostasis
one example of negative feedback, including the identification of a body system responsible for this particular type of feedback
what happens when our bodies cannot properly maintain homeostasis, including one specific example