1. Maintaining The Balance
Homeostasis
Maintaining The Balance

2. Describe how living organisms use ATP.
Monday, December 16th 2013
Bell Ringer:
Objective:
Describe how living organisms use ATP.
SWBAT: Compare and Contrast positive feedback and negative feedback in a Venn Diagram.

3. Review: Be Prepared To Share
Speak with your neighbors for 1 minute about homeostasis.
Write down the definition of homeostasis in your own words.
Why is homeostasis important?
Be Prepared To Share

4. How does the body work to maintain Homeostasis?
Specialized cells in our bodies work to maintain our
Temperature pH
O2 and CO2
Level of energy molecules such as glucose

5. How do our bodies regulate homeostasis?
Feedback mechanisms
Positive Feedback
Negative Feedback

6. Set Point- Degree of Normalcy that must be maintained
Note how the new radar speed signs provide feedback on how much your speed deviates from the set point. The natural thing for the driver to do is to get as close to the set point as possible. When the speed of the car goes above the set point the drive slows down, but when the speed goes too far below the set point the driver speeds back up.

7. Negative Feedback
Feedback mechanism that returns a system to a set point once it deviates (goes away from) past the set point.
ex. Thermostat

8. How does a thermostat work?
Take 1 min and talk to the people at your table about this answer.

9. Negative Feedback (Example)
You set the temperature (let’s say 72 degrees)
It get’s too hot in the room.
The Air conditioner turns on.
The temperature lowers to 72.
The air conditioner turns back off.

10. Think, Pair, Share
Think quietly for one minute about an example of a negative feedback mechanisms we have in our body, in our homes, or in nature.
Speak with your partner about another way you think our body uses negative feedback to maintain homeostasis.
Be prepared to share!
Hint: Think about how we maintain our body temperature, our energy, and our breathing.

11. Check For Understanding
What happens when the body cannot regulate the setpoint of blood glucose???
Answer: Diabetes

12. DIABETES
Diabetes is a perfect example of what can happen when there is a malfunction in negative feedback systems within the body. Considering that we’ve been discussing glucose over the past few weeks, this would be another way to connect this material to prior knowledge.

13. Global Diabetes Scale
% of Diabetes

14. Positive Feedback
In a positive feedback system the change will continue to deviate from the set point until something happens in the body to stop it.

15. Positive Feedback Example
Child birth

16. Think, Pair, Share
Think quietly for one minute about positive feedback mechanisms we have in our body.
Speak with your partner about one way you think our body uses positive feedback to maintain homeostasis.
Be prepared to share!
Hint: Think about how your body processes energy or food.

17. Compare and Contrast negative and positive feedback in a Venn Diagram.
With Your Table:
Compare and Contrast negative and positive feedback in a Venn Diagram.

18. Summary Analysis Questions
Work on independently
Get a stamp for Credit!
**Reminder – Silent and focused (no questions!)
When your body temperature goes up, what happens to your amount of sweat?
When you sweat, what happens to your body temperature?
When your body temperature goes back down, what happens to your amount of sweat?
What type of feedback mechanism was used?