From the latin irritabilĭtas, irritability is the propensity to become irritated (feeling angry or feel morbid excitation in an organ or a part of the body). It can be defined as the ability possessed by an organism to react or to respond in a non-linear manner towards stimulation.
That said, the irritability allows that an organization can identify any negative change in the environment and respond to such alteration. This response may have pathological or physiological effects.
Irritability is considered to be a homeostatic beings capacity alive to respond to stimuli affecting their well-being or their natural state. Thanks to this ability, the beings living arrive to adapt to changes and ensure their survival. It is noted that meant by homeostasis the totality of phenomena of self-regulation to preserve the consistency of the properties and composition of the indoor environment of an organism.
It is possible to distinguish two types of stimuli that trigger irritability: internal/endogenous stimulation (which occur inside the body) and external/exogenous stimulation (those that come from the environment). The temperature, the chemical composition of the soil, water or air, light, and pressure are stimuli that may be at the origin of the reaction of the organism.
While in a unicellular organism all individuals respond to stimulation, in the case of multicellular organisms, the reaction depends on certain cells depending on the type of stimulation.
Irritability may be motivated by psychological questions and speak with exaggerated or disproportionate reactions. For example: "I'm sick of your irritability!» I simply asked you to turn down the volume and you have answered me with insults.