Positive and negative feedback

The feedback is a process in which a system responds to some action, thanks to the information it obtains on the effects of said action. The response of the system is intended to maintain its original state, or for it to be altered.

The positive feedback occurs when they are promoted changes in a system, in response to actions that caused some alteration in it.

The negative feedback look for him balance or original state of the system is maintained, responding with the aim of reducing the effects of the actions that caused a change.

It can be said that positive feedback seeks to make things "change", while negative feedback causes things to "stay the same".

	Positive feedback	Negative feedback
Definition	It is when a system responds to an action promoting any change that has been introduced in it..	It occurs when a system seeks to reduce or end the effects of an action that have altered the system itself.
Characteristics	Produces instability in the system. It is less common to occur in humans. It can occur in natural, social and object systems. It can cause a vicious cycle. External factors are necessary to be able to stop it.	Try to keep a system at a point of equilibrium. It is common in human biological processes. It can occur in natural, social and object systems. Usually stops without the intervention of external factors.
Relationship with homeostasis	It is not common that it is related to homeostasis.	Has an intrinsic relationship with homeostasis.
Examples	The menstrual cycle. Contractions during labor. Blood clotting.	Regulation of body temperature. Regulation of pH in the blood. Regulation of blood pressure.

What is feedback?

The feedback is a process that encompasses answer to actions that alter the state in which a system is at a given moment.

This process occurs when the effect of the action of a system is transformed into information going out and back to this with alterations caused by some phenomenon. The system then determines how to act based on the information obtained.

The information communicates the changes that have occurred to the system, triggering a set of reactions that try to return the system to its original state or stimulate the changes introduced in it..

A system is characterized because its constituent parts form a Unit and they work together according to a objective. The system that goes through the feedback process can be a natural organism (any living being, body organs), a social entity (a political party, a company, an economic system) or of another nature (an electronic device, a plan of business).

There are two types of feedback that generate some kind of reaction in a system: positive feedback and negative feedback. These are differentiated by the response they generate to the changes introduced in the system.

The positive feedback encourages change introduced into the system, increasing the stimulus that broke into the system. In the case of negative feedback, is looking for him balance or original state the system is maintained, reducing the stimulus that produced the change.

Feedback loop

The feedback process has a dynamic of output and input of information that causes some type of reaction in a system. This dynamic or movement is known as a feedback loop..

Social, biological, or other systems are affected by these feedback loops.

Composition of a feedback loop

• These loops are made up of a series of variables liable to be monitored during the feedback process: for example, body temperature or blood pressure.
• Receivers in the body: they are sensors that perceive any change in these variables.
• The control center system: make a decision based on the information received.
• A effector: correct the state of the variable or stimulate changes in it.

What is positive feedback?

The positive feedback is a type of feedback that promotes change within a system. This takes a system to a state different from the original state in which it was at a given moment.

When promoting change in a system, positive feedback is associated with introduction of instability in the same. There is a chain reaction that breaks through the state of the system, stimulating the continuous and accelerated growth of some action, as well as its effects.

Characteristics of positive feedback

• Promotes change in the state of a system.
• Occurs less frequently in human biological processes.
• Increase the rate at which the action that destabilizes the system occurs.
• Your results are exponential.
• Positive feedback on the homeostasis process is rare.
• It can be causing a vicious cycle, since it degenerates a state of balance.
• It is common for external factors to come into play to stop a positive feedback process.

Stages of positive feedback

1. A stimulus breaks into a system, generating changes.
2. Information on the changes that have occurred is perceived by the system control center.
3. The system control center performs a (re) action in the face of these changes, controlling how it will respond to them.
4. There is an effect to the response or reaction, in line with the initial stimulus to promote or generate more changes.

Positive feedback example

The blood clotting is an example of positive feedback. Blood stays as a fluid within the body. When blood vessels are broken, clotting mechanisms are activated in the blood to protect the body from bleeding, sealing the site of damage.

The positive feedback mechanism of coagulation works as follows. When a blood vessel breaks, a surface is exposed that activates proteins. These proteins, in turn, act on other proteins, as a chain reaction, until they form the fibrin mesh that seals the wound..

What is negative feedback?

The negative feedback promotes the state of a system to be kept in Balance, when it undergoes changes caused by some action. This type of feedback seeks the stability of a system.

Its name does not refer to a "bad" or counterproductive process. What happens is that negative feedback opposes the changes that disrupt the equilibrium in a system.

Negative feedback reacts to a stimulus and tries to stop it, reducing its impact. The objective is to return the system to its original state.

For example, body temperature is regulated through negative feedback. Faced with a rise in body temperature, it reacts by producing sweat. In this way, sweat allows the body to cool down.

Characteristics of negative feedback

• Reduces the alterations that are introduced into a system.
• It is more common in the biological processes of the human body.
• Minimizes the rate at which an action occurs (recovering the original state of the system).
• It is related to the process of homeostasis.
• Its effects are not exponential.
• It is common for a negative feedback process to stop on its own when balance has been re-established..

Stages of negative feedback

1. A stimulus or signal breaks into a system, generating changes.
2. Information on the changes that have occurred is perceived by the system control center.
3. The system control center performs a (re) action on these changes, controlling what response there will be.
4. The effect or response tries to eliminate or reduce the stimulus that generated the changes, to restore the original balance.

Example of negative feedback

The process of regulation of human body temperature is an example of negative feedback. The hypothalamus is the control center that regulates body temperature. When the skin temperature is above or below 37 ° C, the hypothalamus activates different processes to correct this imbalance.

In the event that the temperature is higher at 37 ° C, sweat occurs, which evaporates on the skin, cooling it. If the temperature is less than 37 ° C, a process known as thermogenesis shivering. Basically, involuntary body movements occur in order to increase body heat and reach the original temperature level.

Negative feedback and homeostasis

The homeostasis occurs when an organism (system) regulates its internal processes in order to Keep the balance and ensure its proper functioning.

This regulation is due to the interaction that an organism has with an external environment that causes changes in the internal environment of the organism.

• Negative feedback has a particular relationship with the phenomenon of homeostasis. It is used as a control mechanism to return to the original equilibrium state of the organism.
• Positive feedback, on the other hand, stimulates any action that causes change in an organism, being contrary to homeostasis.

The way in which homeostasis controls the processes of an organism to keep it in balance can be understood when you think about the way in which an animal regulates its body temperature.

For example, an organism endotherm (warm-blooded animals) use homeostasis to regulate their body temperature, despite temperature changes in the environment.

This is the case with any mammal, like a human or gorilla, who needs a greater amount of energy to be able to maintain their body temperature.

On the other hand, organisms ectotherms (cold-blooded animals) use the environment they are in to regulate their body temperature, consuming less energy. In this case, the ability to carry out homeostasis to regulate temperature is less than in endotherms..

This would be the case of reptiles, like a crocodile, who take sun baths to maintain their body temperature.