Homeostasis

Homeostasis is the maintainence of relatively stable conditions throughout the body.

Every body structure has one or more homeostatic devices. These devices are mainly under the control of two body systems:

1. Nervous System-detects changes and sends messages in the form of nerve impulses to organs that can counteract the change. The nervous systems causes rapid corrections of stimuli.
2. Endocrine System-corrects homeostatic imbalances by secreting hormones into the blood. It works more slowly than the nervous system.

Feedback Systems

• Homeostatic mechanisms utilize feedback mechanisms: a cycle of events in which the status of a body condition is continually monitored, evaluated, and changed.
• The condition a feedback mechanism is monitoring is called the controlled condition.
• A stimulus-is any disruption that causes change in the controlled condition. This stimulus may be due to internal, external, or social factors.

There are 3 basic components to any feedback system:

1. Receptor-a body structure that monitors changes in a controlled condition and sends input to the control center.
2. Control Center- sets the range of values within which a controlled condition should be maintained, evaluates the input received from receptors, and generates output commands when they are needed.
3. Effector-a body structure that receives output from the control center and produces a response or effect that changes the controlled condition. *Nearly every organ or tissue can behave as an effector.