1. Homeostasis A state of balance in the body Whoa

2. Maintenance of a stable internal environment = a dynamic state of equilibrium Homeostasis must be maintained for normal body functioning and to sustain life Homeostatic imbalance – a disturbance in homeostasis resulting in disease

3. Overview of Homeostasis

4. Maintaining Homeostasis The body communicates through neural and hormonal control systems The primary systems responsible for maintaining homeostasis are the nervous and endocrine systems.

5. Components of Feedback Mechanisms Variable-factor or event being regulated. Set point-ideal normal value Receptor Responds to changes in the environment (stimuli) Sends information to control center

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

7. Feedback Mechanisms Negative feedback Includes most homeostatic control mechanisms Shuts off the original stimulus, or reduces its intensity Works like a household thermostat

8. Human Example of Negative Feedback Human example: shivering in response to cooling of body during cold weather or sweating when their core temperature gets too hot. Homeostasis allows an organism to remain in balance with its environment. If homeostasis is not maintained, it can harm or kill the organism.

9. Feedback Mechanisms Positive feedback Increases the original stimulus to push the variable farther In the body this only occurs in blood clotting and birth of a baby

10. High-Wire Artist Model With your elbow partner, identify the following: Variable Setpoint Receptors Control Center Effectors Whoa

11. High-wire Artist Model Variable: position of body Setpoint: directly over the wire Receptors (Sensors): nerve receptors (eyes, inner ears, muscle stretch receptors, etc.) Control Center: brain Effectors: skeletal muscles High-wire artist uses negative feedback to maintain relatively constant position on wire.