Negative feedback
Introduction
Negative feedback is a fundamental concept in the field of control theory and systems biology, playing a crucial role in maintaining stability and homeostasis in various systems. It refers to a mechanism or process that tends to reduce the fluctuations or deviations in a system from its desired state or set point. This is achieved by feeding back a portion of the system's output in such a way that it counteracts any deviation from the set point.
Principle of Negative Feedback
The principle of negative feedback is based on the idea of a 'feedback loop'. In a negative feedback loop, the output of a system is monitored and any deviation from the desired state is detected. This deviation is then fed back into the system in a manner that counteracts the original deviation, thereby bringing the system back towards its desired state.
Negative feedback loops are a common feature in many natural and man-made systems. They are essential for maintaining stability in these systems, preventing them from spiralling out of control due to positive feedback or other destabilizing factors.
Negative Feedback in Biological Systems
In biological systems, negative feedback mechanisms are crucial for maintaining homeostasis – the state of stable internal conditions that is necessary for the survival of living organisms. These mechanisms operate at all levels of biological organization, from the molecular and cellular levels to the level of whole organisms and ecosystems.
For example, in the human body, the endocrine system uses negative feedback loops to regulate the levels of various hormones. If the level of a particular hormone becomes too high, this is detected by the body, which responds by reducing the production of that hormone. Conversely, if the level of the hormone becomes too low, the body increases its production. This ensures that the level of the hormone remains within a narrow range, despite changes in the external environment or the body's internal state.
Negative Feedback in Engineering and Technology
In engineering and technology, negative feedback is used to improve the performance and stability of various systems and devices. For example, in electronic amplifiers, negative feedback can be used to reduce distortion and noise, improve bandwidth and linearity, and stabilize the gain.
In control systems, negative feedback is used to maintain a desired state or output, despite disturbances or changes in the system's input. This is achieved by continuously monitoring the system's output, comparing it with the desired state, and using the difference (or 'error signal') to adjust the system's input in a way that reduces the error.
Negative Feedback in Economics and Social Sciences
In economics and social sciences, negative feedback mechanisms can help to stabilize markets and social systems. For example, in a market economy, if the price of a commodity rises above its equilibrium level, this will tend to reduce demand and increase supply, thereby pushing the price back down towards its equilibrium level. This is an example of a negative feedback loop.
Similarly, in social systems, negative feedback mechanisms can help to maintain social order and prevent extremes of behavior. For example, social norms and laws can act as negative feedback mechanisms, discouraging behavior that deviates from the norm and encouraging conformity.