5/16: Feedback Loops

Let Me Give You Some Feedback

The feedback is... you are awesome at science! Today we are going to learn about positive and negative feedback loops, and identify examples in the body, and in Earth systems (like the carbon cycle). NOTE: We usually use the word positive to mean good, and negative to mean bad, but that is not what it means for feedback loops! Read the definitions below to understand.

All systems have a target set point. For example, your body has a certain temperature that helps it work best and stay healthy - (usually about 98.6 degrees Farenheit). Negative feedback is when a system shifts to stay at a target set point. For example, if you get too cold, your body will shiver to warm up. If you get too warm, you will sweat to cool down. This is negative feedback - staying at a set point.

Positive feedback occurs when a system moves away from the target set point. When apples are ripening on a tree, they release a kind of gas that signals the other fruits around it to ripen as well. Soon all the apples in the orchard are turning ripe! This is positive feedback, because the system has moved away from the set point, and will not go back to being unripe.