What is negative feedback in homeostasis?

The feedback or negative feedback in homeostasis it is a key process for the various body systems to maintain their normal state. The normal state of the body is called baseline state and the homeostasis it is, in short, the maintenance of this basal state. Negative feedback cannot help keep the body exactly at the ideal baseline values, but works by keeping the body within a range of values ​​considered normal and in which it can perform its functions.

For example, if the body temperature rises too high, processes such as sweating are set in motion to cool the body. If your body temperature drops too low, you begin to shiver to help increase your temperature with muscle movement. It is called negative feedback (sometimes abbreviated NFB). negative feedback) because the reaction is in the opposite direction to the signal received: in this example, a temperature increase signal is received and an action is taken to reduce it and vice versa.

How does it work?

There are normally three parties involved in negative feedback: the so-called receiverthe control center and the call effector. The receptor is the organ or tissue that intervenes in the negative feedback process, registering the values ​​of some variable of the organism; these variables can be very different, for example, temperature, blood pressure or blood glucose concentration. The information collected by the receiver is continuously sent to the control center. When the received values ​​go out of the normal ranges, the control center will send orders to the effector organs so that they begin to function in a certain way that helps to return the values ​​of the variable to the normal values ​​in the basal state.

Let us see, for example, how a process of negative feedback to maintain blood pressure. The receptors are, in this case, pressure-sensitive nerve endings and are found mainly in veins and arteries near the heart and head. These receptors send nerve impulses to the part of the brain that regulates the heartbeat; this part of the brain would be the control center. From this regulatory center, signals are sent back to the effector organ, in this case the heart, so that it increases or decreases its rhythm and thus regulates blood pressure. (Note: many other factors are involved in the regulation of blood pressure, only one has been discussed to illustrate the concept of negative feedback in homeostasis in a simple way).

A similar concept is used in psychology. Negative feedback in psychology is useful for understanding basic motivations of individuals. For example, when a person is deprived of food they become increasingly hungry. The feeling of being hungry would be here a negative feedback mechanism to lead the person to eat and bring the body to the basal nutritional state. When the person eats, the feeling of hunger disappears through the feedback mechanism itself that informs the regulatory center that they have already eaten.

What would happen if there was no negative feedback?

As we have seen, the organism needs to maintain biological parameters within a certain range, frequently a narrow range. Outside this range, problems and more or less serious consequences for healthThey can even mean death.

For example, under normal conditions, body temperature is between 37.2 and 37.6 ºC. Outside these values, body temperature can vary for various reasons that can be considered normal, but if it falls below 33 ºC, hypothermia will occur and if it rises above 42 ºC, hyperthermia will occur. Both hypothermia and hyperthermia are situations that can trigger serious consequences up to the point of death. In other cases the effects may not be visible in the short term but can still produce serious long-term effects. For example, hypertension may not develop noticeable symptoms for patients but can be the cause of heart attack and other fatal cardiovascular diseases.

Therefore, negative feedback is the main control mechanism of homeostasis and as such it is essential to maintain the different parameters of the organism between the values ​​at which it can perform its functions. If negative feedback didn't exist, we would die. In fact, when negative feedback control mechanisms fail, medicine must be used to help the body maintain homeostasis.

Reference

  • Saladin, Kenneth S. Anatomy and Physiology—The Unity of Form and Function, 2nd ed. Dubuque, IA: McGraw-Hill Higher Education, 2001.
Go up