The human body maintains homeostasis through thousands of control systems that primarily use negative feedback. Negative feedback occurs when the output of a system counters changes to the input, stabilizing the system. In contrast, positive feedback acts to amplify responses through self-reinforcing cycles. Both negative and positive feedback loops help explain important biological processes like homeostasis, blood clotting, and childbirth, demonstrating how feedback mechanisms underlie many complex regulatory functions in the body.

1. Control Systems
The human body has thousands of control
systems also known as compensatory
mechanisms. These control systems are
important to maintain homeostasis. Most of
these control systems involve negative
feedback.

2. Negative Feedback
• Occurs when the output of a system acts to
oppose changes to the input of the system,
with the result that the changes are attenuated.
If the overall feedback of the system is
negative then the system will be stable.
Biology → Homeostasis
Mechanics → Equilibrium

3. Negative Feedback

4. Negative Feedback

5. Positive Feedback
• Acts to increase the magnitude of a response or
disturbance.
• Often referred to as a viscous cycle or runaway.
• Amplification

6. Positive Feedback
Biological Examples:
• Childbirth
• Blood clotting
• Lactation
• Generation of a nerve signal

7. Positive Feedback

8. Feedback Loops
• Provide an ideal method to assist with the
understanding biological processes.
• Provide an ideal method to understand
compensatory mechanisms.
• Provide an ideal method to fully appreciate the
complexity homeostasis and amplification.