5-6) Homeostasis and Negative & Positive Feedback

Homeostatis- is the ability to maintain relatively stable internal conditions even though the outside world changes continuously. Homeostasis indicates a dynamic state of equilibrium (a balance) in which internal conditions vary but, will always within relatively narrow limits. The body is in homeostasis when its needs are adequately met and it is functioning smoothly. Communication is essential for the body to complete homeostasis. Without proper communication, blood containing vital nutrients cannot be provided throughout the body, the body's heart activity cannot be monitored properly. Also, the body's waste(s) may begin to accumulate through the body's blood stream and the body's temperate cannot be controlled.

-In NEGATIVE FEEDBACK mechanisms, the output shuts off the original stimulus or reduces its intensity. These mechanisms cause the variable to change in a direction opposite to that of the initial change, returning it to its "ideal" value. Basically, negative feedback mechanisms find a problem and then fight to change that problem or decrease that problem in order to bring the body back to a normal state. The main goal of negative feedback mechanisms it to prevent sudden severe changes within the body.
-In POSITIVE FEEDBACK mechanisms, the result or response enhances the original stimulus so that the activity (output) is accelerated. The change that occurs, proceeds in the same direction as the initial disturbance, making it "positive". Positive feedback causes the variable to deviate further from its original value or range. For example the enhancement of labor pains is an example of a positive feedback machanism. One might think this is a "negative" thing because labor is extremely painful but, this is actually a good thing because the body is communicating with itself that it is time for the baby to be born and to begin labor.
*Negative feedback mechanisms maintain some physiological function or keep blood chemicals within narrow ranges while positive feedback mechanisms control infrequent events that do not require continuous adjustments.

*Most disease is caused because of a disturbance within the body called homeostatic imbalance. Within age, the body's control system becomes less efficent, increasing the risk of illness. Homeostatic imbalance can also be caused by destructive positive feedback mechanisms taking over the job(s) of the overwhelmed negative feedback mechanisms.