1. 28.3 Interactions Among Systems KEY CONCEPT Systems interact to maintain homeostasis.

2. 28.3 Interactions Among Systems 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.

3. 28.3 Interactions Among Systems Organ systems must also work together to keep the organism healthy. –Organ systems work together to produce Vitamin D. –Thermoregulation maintains a steady body temperature. 1 2 34 Skin absorbs UV light Liver produces inactive vitamin D Kidneys produce active vitamin D Active vitamin D used in bones UV light

4. 28.3 Interactions Among Systems A disruption of homeostasis can be harmful. Homeostasis can be disrupted for several reasons. –sensors fail –targets do not receive messages –injury –illness

5. 28.3 Interactions Among Systems 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 34 Pancreas cells attacked;insulin declines Blood glucose levels rise, Body burns fat; blood more acidic, Cells impaired; all organs damaged. pancreas fats kidneys