1. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Life Functions— What the body is built for 1.Maintain boundaries 2.Movement 3.Responsiveness 4.Digestion 5.Metabolism—chemical reactions within the body 6.Excretion 7.Reproduction 8.Growth

2. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Survival Needs 1.Nutrients 2.Oxygen 3.Water 4.Stable body temperature 5.Atmospheric pressure

3. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Interrelationships Among Body Systems Figure 1.3

4. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Homeostasis  Homeostasis—  Homeostasis is necessary  Homeostatic imbalance

5. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 1.4, step 1a Variable (in homeostasis)

6. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 1.4, step 1b Stimulus: Produces change in variable Variable (in homeostasis) Imbalance

7. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 1.4, step 2 Change detected by receptor Stimulus: Produces change in variable Receptor (sensor) Variable (in homeostasis) Imbalance

8. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 1.4, step 3 Change detected by receptor Stimulus: Produces change in variable Input: Information sent along afferent pathway to Receptor (sensor) Variable (in homeostasis) Control center Imbalance

9. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 1.4, step 4 Change detected by receptor Stimulus: Produces change in variable Input: Information sent along afferent pathway to Receptor (sensor) Effector Variable (in homeostasis) Output: Information sent along efferent pathway to activate Control center Imbalance

10. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 1.4, step 5 Change detected by receptor Stimulus: Produces change in variable Input: Information sent along afferent pathway to Receptor (sensor) Effector Variable (in homeostasis) Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis Output: Information sent along efferent pathway to activate Control center Imbalance

11. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Maintaining Homeostasis  The body communicates through neural and hormonal control systems  Receptor  Control center  Effector Afferent Pathway Efferent Pathway

12. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Feedback Mechanisms  Negative feedback

13. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Feedback Mechanisms  Positive feedback