1. Human Systems & Homeostasis

2. How does this ice climber hang on to his body temperature?

3. What is homeostasis?
Ability of an organism to maintain its internal environment (within set ranges), despite changes to its internal or external environment

4. What things in your body need to be kept within a set range?
**Body Temperature
Blood Pressure
Blood pH
**O2 and CO2 Concentration
Osmoregulation-Water Balance
**Blood Glucose
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5. How does homeostasis work?
Specific organs and structures must communicate with each other in response to changes in the body
all images generated by Microsoft Clip Art Gallery

6. Negative feedback loops are necessary for homeostasis.
Feedback compares current conditions to set ranges.
Negative feedback counteracts change.
O2 / CO2 level returns to normal
Holding breath, CO2 levels rise,
Negative Feedback Loop
Control system forces exhale, inhale

8. Explain this negative feedback loop

9. Turn to a Partner: Explain this Feedback Loop
Glucose levels rise after a meal.
Insulin is produced and glucose levels fall to normal again.
Glucose
Concentration
Normal
Time
Meal eaten

10. Positive feedback increases change
Example: Torn blood vessel stimulates release of clotting factors
platelets
fibrin
white blood cell
red blood cell
blood vessel
clot

12. Positive or Negative Feedback??

13. Positive or Negative Feedback??

14. Positive or Negative Feedback??

15. Positive or Negative Feedback??