The methods of homeostatic regulation
Living beings are exposed to a multitude of stimuli continuously. Therefore, it is necessary to have mechanisms of homeostatic regulation capable of maintaining internal stability.
Homeostasis and internal environment
In the mid-nineteenth century, the French physiologist Claude Bernard noticed the constancy of the internal environment in which the cells of organisms were arranged, in view of the changing properties of the exterior.
Almost a century later, the American physiologist WB Cannon established that this balance was the result of a set of physiological mechanisms capable of maintaining a series of concentrations or internal values necessary for survival.
Canon proposed the term homeostasis
em> to allude to the 'stable' character of the internal environment, as opposed to the external fluctuation. Paradoxically, the complexity of these physiological processes lies in a constant self-regulating dynamic .Mechanisms of homeostatic regulation
The cells of living beings only maintain their viability within a few ranges of temperatures, pH, ionic concentrations and specific nutrients according to the species. However, organisms depend on a changing external environment to obtain the matter and energy necessary for internal balance.
The homeostatic regulation mechanisms can be classified as:
- Negative feedback : occurs when the value of a variable is higher or lower than that required for the operation of a certain process or physiological mechanism. In response, a regulatory mechanism is activated to inhibit the synthesis of said variable or decrease its power.
The regulation of blood glucose levels or the maintenance of body temperature are some of the biological processes regulated in this way.
- Positive feedback : less frequent than the previous mechanism, contributes to the increase of a process or function.
It occurs in the initial stages of the action potential, when a small depolarization of the cellular plasma membrane generates the opening of sodium channels that, upon entering the intracellular space, induce the opening of more sodium channels. In this way, a greater cellular depolarization is achieved. There would also be a positive regulation in the early stages of ovulation.
- Anteroalimentation : mechanism that allows an organism to predict highly probable events. It can be both negative and positive in nature and stand out, mainly, in the metabolic chains and the processes of communication and neuronal coordination.
The increase in heart rate in the moments before an effort imminent physical or even the very functioning of the cerebellum, which, in anticipation of the state of the neuromuscular system once the movement starts, can execute the necessary nerve orders.
Homeostasis and Alostasis
Once exposed the homeostatic theory with which Bernard and Cannon justified the stability and functioning of the internal environment, in 1988 the neuroscientist Sterling proposed an opposite view or, as has been discovered later, complementary to homeostatic regulation: the allostasis.
Alostasis is a mechanism regulator that, unlike the equi Librio homeostatic, proposes that organisms to deal with disturbances of the external environment alter the constancy of the internal environment.
