Positive and negative feedback

Since I always find learning easier when I teach things to other people, here's my attempt at a school blog!

For now, the topics will mostly be biology 12. My curriculum uses Inquiry into life by Sylvia S Mader, Eighth edition.

Biology 12 is all about memorization as the theories themselves aren't too hard to understand. The memorization comes in with terminology. What seems like endless cell organelles and functions!! Everything is unfamiliar since it's new, it's a challenge to memorize and of course, I've been out of school for so long tbat the memorization is that much more difficult. So, here goes!

Disclaimer: I am not a biology expert and this is simply my own take on the subject and this blog is mostly for me and my own learning. If you happen to find the blog, Well, use at your own risk!!



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Positive feedback


The first assignment I have is to learn what Positive and Negative feeback are and learn how to diagram feedback loops.

Positive feedback defined by my handout is "A mechanism that brings about an ever greater change IN THE SAME DIRECTION".

There are many examples around on how this works but I'd like to understand the initial definition myself before I get into that. I'm convinced that I can't find a better explanation within my own head but I'll try.

my definition:

Positive feedback is when a stimulation causes a reaction. This reaction causes more stimulus and in return, causes another reaction to occur on top of the original reaction. It builds and builds and builds....


like a fever. a fever can cause metabolic changes to occur. These metabolic changes push the fever even higher. A situation like this is where positive feedback loops can be harmful.



Positive feedback can be a GOOD thing though, like in blood clotting to heal a wound or in the body's digestion of protein.


Childbirth is another example of positive feedback. The baby's head presses against the cervix causing the pituitary glad to release oxytocin. Oxytocin causes the uterus to contract again, pressing the baby's head against the cervix again, stimulating it.... this continues until birth occurs.

Positive feedback helps the body cope with intermittent events.


Negative feedback.


Self regulatory mechanism that is activated by an imbalance and results in a fluctuation above and below a mean.


So... much... scientific jumble! (to me, anyhow)

Negative feedback is the body's way of correcting a [low] imbalance by activating it's regulatory system. Like, when blood sugars are too high. The pancreas releases insulin to correct it.

sometimes, it can be harmful- like if you are diabetic and your pancreas doesn't stop releasing insulin. Now the blood sugar is too low.

Basically, any time the body feels that a necessary resource is too low, the negative feedback response kicks in and a hormone is released to bring the body's levels back to an even keel.

Summary notes:

positive feedback helps the body deal with intermittent events like injury, sickness or birth.
Negative feedback is used for maintenance of the body on an ongoing basis.