Homeostasis

Is It Cold In Here, Or Is It Just Me?

There are so many amazing things that make up and control the human body. Did you ever wonder how our bodies maintain a temperature of 98.6? How our blood sugar remains at normal acceptable levels, or how the calcium content in our blood remains stable? These things and many more are maintained as part of a process called homeostasis. Homeostasis is the body's maintenance of a stable internal environment, and depending on what particular aspect of the body's physiology you are talking about there are corresponding systems to maintain this normal, stable range.

The body maintains homeostasis through a self regulating control system, or "homeostatic mechanism" (Shier) if you will. All of these homeostatic mechanisms share these same three components; (1) receptors (2) a control center, and (3) effectors. I will explain how the body maintains a normal temperature range and I will use a home heating/cooling system as a comparison as we go along to help make this process easier to understand. Please refer to the accompanying diagram. (Shier) Your body and your homes heating/cooling system work on a negative feedback system. This means that there is a normal set point, such as with the thermostat in your home. When the thermostat is set at 70 degrees and the ambient room temperature drops below that to 68 degrees, then the thermostat will start the furnace to reverse the direction of the temperature and return it to 70 degrees. The desired result is to negatively affect the temperature and reverse it to the desired setting, hence the name negative feedback. With negative feedback explained

we will start at 98.6, the normal body temperature. If your temperature rises above 98.6, this is a stimulus. This stimulus is picked up by the first component of the homeostatic mechanism, which you will recall is a receptor. In this case, the receptor is called a thermo receptor. Likewise, if the temperature in your home rises above 98.6 it is detected by a receptor, the thermostat. Next, the body's thermo receptors would send a signal to the control center, the second component of the homeostatic mechanism which is the hypothalamus in the brain. By comparison, in the home system, the thermostat would detect the room temperature and send a signal to the control center, which in this case is the air conditioning unit. Immediately following the signal sent to the hypothalamus from the thermo receptors, the hypothalamus would set into motion the body's correction process to reverse this irregularity by triggering