1. Life Functions & Homeostasis

2. Necessary Life Functions 1.Maintain boundaries 2.Movement  Locomotion  Movement of substances 3.Responsiveness  Ability to sense changes and react 4.Digestion  Break-down and absorption of nutrients

3. Necessary Life Functions 5.Metabolism—chemical reactions within the body  Produces energy  Makes body structures 6.Excretion  Eliminates waste from metabolic reactions 7.Reproduction  Produces future generation 8.Growth  Increases cell size and number of cells

4. Survival Needs 1.Nutrients  Chemicals for energy and cell building  Includes carbohydrates, proteins, lipids, vitamins, and minerals 2.Oxygen  Required for chemical reactions

5. Survival Needs 3.Water  60–80% of body weight  Provides for metabolic reaction 4.Stable body temperature 5.Atmospheric pressure  Must be appropriate

6. Interrelationships Among Body Systems Figure 1.3

7. Homeostasis  Homeostasis—maintenance of a stable internal environment  A dynamic state of equilibrium  Homeostasis is necessary for normal body functioning and to sustain life  Homeostatic imbalance  A disturbance in homeostasis resulting in disease

8. Homeostasis - Fishbowl Model FishbowlHuman BodyFunction Water Glass bowl Fish Air Pump Filter Heater Feeder Everything working togetherHomeostasis! Bodily Fluids Skin Cells Lungs Kidneys Muscles Digestive System Internal env’t Barrier Maintain life Keep high O 2 level Remove wastes Constant temp High nutrients

9. Figure 1.4 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 Control center Imbalance Output: Information sent along efferent pathway to activate

10. Figure 1.4, step 1a Variable (in homeostasis)

11. Figure 1.4, step 1b Stimulus: Produces change in variable Variable (in homeostasis) Imbalance

12. Figure 1.4, step 2 Change detected by receptor Stimulus: Produces change in variable Receptor (sensor) Variable (in homeostasis) Imbalance

13. 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

14. 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

15. 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

16. Maintaining Homeostasis  The body communicates through neural and hormonal control systems  Receptor  Responds to changes in the environment (stimuli)  Sends information to control center

17. Maintaining Homeostasis  Control center  Determines set point  Analyzes information  Determines appropriate response  Effector  Provides a means for response to the stimulus

18. Feedback Mechanisms  Negative feedback  Includes most homeostatic control mechanisms  Shuts off the original stimulus, or reduces its intensity  Works like a household thermostat  Positive feedback  Increases the original stimulus to push the variable farther  In the body this only occurs in blood clotting and during the birth of a baby

19. Homeostasis Video