Chapter 1: Homeostasis

photo from found on Images

Homeostasis is a state of balance in the body. One effective mechanism our bodies use to maintain homeostasis is a negative feedback inhibition. Our bodies can sense deviations from a set point, and send the information to the appropriate integrating center, usually the brain, which will then respond by stimulating or inhibiting effectors, usually muscles or glands, to correct the deviation. For example, blood glucose levels are controlled by a negative feedback loop. When blood glucose levels get too high, the integrating center releases hormones that cause insulin to be released into the blood stream. This allows the cells to use the glucose for energy and thereby reducing the blood glucose level back to normal, or its set point. If blood glucose gets to low, hormones (effectors) are released to cause the liver to secrete glucose into the blood stream to bring the blood glucose level back up to normal levels.

Diabetes Mellitus is an example of homeostasis failure. The following video explains this:

photo by Jennifer Noem

The importance of maintaining homeostasis was never more clear to me a few weeks ago. My daughter, Payton, is a picky eater and on this day she refused to eat breakfast, instead only drinking her juice. Since this is normal for her I really didn't think too much of it. I can usually get her to eat a decent lunch on these days, but on this day we were going shopping in Sioux Falls. Thinking we could get one store out of the way before heading to lunch, we went to Gordman's. As things tend to happen, it took us about twice as long as I thought it would and while my older daughter was trying on some clothes, I noticed that Paytie had stopped responding to me. With growing panic I realized that she was diaphoretic, limp, confused, and getting worse. Trying to remember my EMT training and what I had learned so far in nursing classes, I began to assess her symptoms. The thing that kept coming to my mind was hypoglycemia even though she has no history of this at all. Thankfully, there were angels watching over her and another shopper noticed what was going on. She had a candy bar in her purse and we were able to get her to eat it little by little. She slowly started to come out of it and within thirty minutes was back to her old self. In this instance, negative feedback inhibition worked to correct the high blood glucose level caused by the orange juice, but since she hadn't eaten anything else and didn't have enough stored glucogon to bring her blood glucose back up to normal levels. Now, regardless of whether she wants to eat or not, I always make sure that she has something nutritious every couple of hours. The battle is definitely worth preventing another hypoglycemic episode.

This is a link from You Tube explaining how Homeostasis works in our bodies.


Fox, Stuart Ira. Human Physiology, 10th Edition. from Images

Noem, Jennifer.