1. KEY CONCEPT Systems interact to maintain homeostasis.

2. DEFINE THESE TERMS (page 858)
Homeostasis-
Feedback-
Negative feedback-
Positive feedback-
Thermoregulation-

3. Each organ system affects other organ systems.
An organ system must do a specific job.
Organ systems must also work together to keep the organism healthy.

4. Organ systems must also work together to keep the organism healthy.
Skin-absorbs UV light to make inactive Vitamin D
Liver-changes inactive D into another compound
Kidneys-convert this D into active Vitamin D. 1 2 3 4
Skin absorbs UV light
Liver produces inactive vitamin D
Kidneys produce active vitamin D
Active vitamin D used in bones
UV light

5. Thermoregulation maintains a steady body temperature
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6. 6.Short term
7.little lasting damage
8.common cold
9.long term
11.Diabetes

7. A disruption of homeostasis can be harmful.
Homeostasis can be disrupted for several reasons.
sensors fail to detect signals
targets do not receive messages
Serious injury
illness
Viruses or bacteria change internal chemistry

8. Short-term disruption usually causes little or no harm.
Long-term disruptions can cause more damage.
Diabetes is a serious long-term disruption of homeostasis. 1 2 3 4
Pancreas cells attacked;insulin declines
Blood glucose levels rise,
Body burns fat; blood more acidic,
Cells impaired; all organs damaged.
pancreas
fats
kidneys