Book : Human Biology
posted by
Posted by: CHELSEA
posted by
Writer CHELSEA

Positive and Negative Feedback

image about


Introduction

When a change of variable occurs, there are two main types of feedback to which the system reacts:

Negative feedback

A reaction in which the system responds in such a way as to reverse the direction of change. Since this tends to keep things constant, it allows the maintenance of homeostasis. For instance, when the concentration of carbon dioxide in the human body increases, the lungs are signaled to increase their activity and expel more carbon dioxide. Thermoregulation is another example of negative feedback. When body temperature rises (or falls), receptors in the skin and the hypothalamus sense a change, triggering a command from the brain. This command, in turn, effects the correct response, in this case a decrease in body temperature.

Positive feedback

A response is to amplify the change in the variable. This has a destabilizing effect, so does not result in homeostasis. Positive feedback is less common in naturally occurring systems than negative feedback, but it has its applications. For example, in nerves, a threshold electric potential triggers the generation of a much larger action potential. Blood clotting and events in childbirth are other types of positive feedback.

Home Heating System Vs. Negative Feedback

When you are home, you set your thermostat to a desired temperature. Let's say today you set it at 70 degrees. The thermometer in the thermostat waits to sense a temperature change either too high above or too far below the 70 degree set point. When this change happens the thermometer will send a message to the "Control Center", or thermostat, Which in turn will then send a message to the furnace to either shut off if the temperature is too high or kick back on if the temperature is too low. In the homeheating example the air temperature is the "NEGATIVE FEEDBACK." When the Control Center receives negative feedback it triggers a chain reaction in order to maintain room temperature.


related articles

Cells of the Human Body

Cells of the Human Bod...

  • Basics
  • posted Date:2017 Sep, 15

IntroductionAlthough there are sp...

read more
Blood

Blood

  • Basics
  • posted Date:2017 Sep, 16

IntroductionThe primary function of blood is to supply nutrients...

read more
The Nervous System

The Nervous System

  • Basics
  • posted Date:2017 Sep, 15

IntroductionThe cent...

read more

Subscribe With Us For Daily Reading Lesson Materials