Friday, September 9, 2011


(Taken from Hole's Anatomy)
Homeostasis is a property or quality of multicellular organism's systems that allow us to maintain a stable environment. To break that down and make it even a little more understandable, we can say homeostasis is a natural quality we have within us to keep a constant internal environment. In order for the body to maintain this internal environment, there are self-regulating control systems through which our body does this process. These control systems have 3 parts to them: Receptors, the control center, and effectors.

  • Receptors: provide information about specific conditions in the internal environment. A receptor may be a molecule or a cell or even a system. The receptor detects the bodies need and then contacts the control center.
  • Control Center: includes a set point (target value of a physiological measure maintained automatically in the body), which tells a particular value should be. An example would include human body temperature at 98.6 degrees Fahrenheit. This center gets the information from the receptor, reads where the body is at compared to where it needs to be, and sends the mission to the effectors.
  • Effectors: can be muscles or glands, which cause responses that alter conditions in the internal environment. Once the effector has the mission it breaks that down into understandable terms for the body to read and it changes the condition or tries to make up for the irregular functions to keep the body stable.

(Taken from Hole's Anatomy)
These 3 parts are referred to as a "homeostatic mechanism". This homeostatic mechanism works together when the receptor measures your stability from the set point and the effectors are activated to fix the variables that are off. As the conditions return to normal, the effectors gradually shut down because they have done their job and this process is refered to as negative feedback. The image 1.7 shows us an example of how all the reactors work together to get the room temperature back to normal. Another example of negative feedback would be when you are running and your body starts to heat up. When it heats up, your body starts to sweat causing beads of water to evolve on your skin. As you run, this perspiration begins to evaporate working in a way that cools the body. The sweat ether evaporates into the air or soaks into your jersey keeping you cool and in a sense working as a type of air conditioner. This homeostatic mechanism works to maintain body temperature and cause you not to overheat. Although most body feedback is negative, there is a chance that on occasion you'll see some positive feedback. Positive feedback is a process that moves conditions away from the normal state. Examples of positive feedback include things such as woman's contractions at birth, AIDS, and blood clotting. I'll explain AIDS for a better understanding: when AIDS is in a human system at the beginning of the virus just certain cells in your body are effected, but as the process go on your body multiples the virus and engraves it into your DNA rather than try to fix the problem. This example, like most other positive feedback is not looked upon as good, but not all positive feedback has to have such negative connotations. For example contractions around the birthing period are very well looked upon. A woman has one contraction and that leads to another and another and they build up to help the mother deliver her baby. Positive feedback happens on a much rarer occasion, but it can happen so keep it in mind as well.  

Homeostatis in general is just the process of keeping our bodies in a normal, stable environment. I've learned about the different parts of the homeostatic mechanicisms and about positive and negative feedback. I hope I may have been some help to you as well trying to break down the textbooks and just give you the simple explanation of all this "stuff".


check out this video its a great explaination of
other parts of homeostasis I didn't cover!!

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