1. UNIT 7 LT 6.10.6 HUMAN BIOLOGY “Homeostasis” UNIT 7 LT 6.10.6 SWBAT describe and compare the main functions of human body systems and organs HUMAN BIOLOGY “Homeostasis”

2. Hook http://www.youtube.com/watch?v=vvYRd3o3NWg

3. IBE – JTPS (Justify – Think Pair Share) What happens when you get cold?

4. J-TPS (Justify –Think Pair Share) THINKPAIR SHARE

5. Your body must cope not only with temperature changes but also with pollution, infections, stress, viruses. What keeps your body from breaking down every time the internal or external environment changes? THINK BOX

6. Homeostasis is the regulation and maintenance of the internal environment of the body Homeostasis

7. Conditions within the body must remain within a narrow range – like your body temperature Homeostasis involves keeping the internal environment within set ranges Homeostasis involves keeping the internal environment within set ranges Can you provide other examples of homeostasis? Homeostasis

8. Control systems help maintain homeostasis –Sensors: gather data –Control center: receives data, sends messages –Communication system: delivers messages to target organs, tissues –Targets: respond to change pore sweat glands hair follicle muscle goose bump What do you think it’s the control center of your body?

9. Think Why is it so important to maintain homeostasis within the body? THINK BOX

10. Check your understanding The body’s internal environment must stay 1. within narrow ranges that support human life. 2. the same as its external environment. 3. exactly the same at all times. 4. away from sudden outside temperature changes.

11. Check your understanding Which of the following changes its level of activity in response to a message sent by a control center? 1.Target 2. Sensor 3. Brain 4. receptor

12. Feedback Loops Feedback compares current conditions to a set of ideal values.Feedback compares current conditions to a set of ideal values. In a feedback loop information moves continuously among sensors, a control center, and a target.In a feedback loop information moves continuously among sensors, a control center, and a target. 2 types of feedbacks:2 types of feedbacks: - negative feedback loops - positive feedback loops

13. Negative Feedback Negative feedback: loops are necessary for homeostasis Negative feedbacks counteract any change in the body that moves conditions above or below a set point. They keep the internal environment stable.

14. Negative Feedback Loop Example: Holding breath, CO 2 levels rise Control system forces exhale, inhale O 2 / CO 2 level returns to normal

15. Think How does a thermostat is a good example of how negative feedbacks work? THINK BOX

16. Positive feedback In positive feedbacks, a control center uses information from sensors to increase the rate of change away from the set points. Though not as common in the body, this type of feedback is important whenever rapid change is needed.

17. –Example 1: if you cut your finger, positive feedback mechanism increases the rate of change in clotting factors in the blood until the wound is sealed. - Example 2: release of growth hormones during puberty to accomplish all of the changes that take place at this time Positive Feedback Loop Examples:

18. Check your understanding In a positive feedback loop, the body increases the rate of change 1.toward set values 2. without ever stopping 3. only slightly, then stops 4. away from set points

19. Check your understanding A negative feedback loop causes the body to 1.counteract a change 2. change set points 3. increase the rate of change 4. shut down a control center

20. Summary http://www.youtube.com/watch?v=ZQLruoTR GVk