Positive & Negative Feedback Loops
Caitlin Kresta
Positive Feedback
A positive feedback loop tries to enhance the original stimulus, letting it build and build until the task is complete! Here are some examples:
Childbirth
As the baby pushes harder and harder on nerves in the cervix, more and more oxytocin is released (oxytocin is a hormone that speeds up contractions). This feedback loop crescendo's until the child is birthed.
Blood Clot Formation
When the Fibrin tears in a a blood vessel, Platelet is activated. Platelet holds the red blood cells together, forming a clot, so that no more blood can escape the vessel. This carries on until the tear is patched.
Negative Feedback
Negative feedback loops aim to maintain a certain set point in homeostasis. Here are some examples:
Blood Pressure
When an outside stimulus occurs that causes a drop in blood pressure, the heart and brain detect it. These organs then command an increase in heart rate, which brings the blood pressure back to its' original state.
Body Temperature
When the brain detects that your body temperature is rising or falling, it commands the blood vessels to expand (conserves heat when cold) or to dilate (releases heat into the environment when hot). The brain will do so until you have maintained a normal body temperature.