Emotions are the physiological state, which is the body's response to internal or external irritation and having pronounced subjective color (fear, sadness, joy, anger and other).
Objectively about a particular emotional state can be judged by human behavior, reactions facial muscles, and vegetative shifts in the body (vascular reactions, functional changes in cardiac, respiratory, intestinal, and others). Positive emotions (joy, delight), causing a sharp autonomic changes (elevation in blood pressure, increased heart rate and other), do not provide long-term residual reactions. When negative emotions (fear, grief) autonomic changes have a long, drawn out, which can lead to pathological condition of the body (hypertension, peptic ulcer disease of the stomach, cramps different sections of the gastro-intestinal tract and other neurogenic diseases).
In the mechanism of occurrence of emotions important role of the thalamus and the hypothalamus. Were allocated patterns of CNS excitation which causes positive ("pleasure center") or negative emotion (the"center of displeasure"). These structures include the reticular formation and limbic system. Defeat of these structures pathological process (tumor, trauma, infection) makes people drastic violations of emotional reactions.

Emotions (Franz. emotion, from lat. emovere is to arouse and excite) - subjective experiences associated with responses to external and internal stimuli and with purposeful activities.
General characteristics. Emotions emerged in the process of evolution as a tool fastest and most economical response to external forcing and meet the needs of the body.
The main biological significance of emotions is to evaluate the internal state of the organism, which allows the animal and the man quickly and reliably make the adaptive response. Covering the entire body, emotions produce almost instant integration of all functions, thanks to which determined the usefulness or harmfulness of this factor. Playing the role of a kind of "bearing", emotions enable the body to produce a reaction, often even before the localization effects (P. K. Anokhin).
No less important is the role of emotions is to stimulate purposeful reactions. In any human activity, aimed at achieving some goal, the success accompanied by positive emotions. On the other hand, the emergence of all human needs are always accompanied by a feeling of dissatisfaction - emotions unpleasant, painful character. This feeling is enhanced when any failure to satisfy the demand, i.e. when the result of the committed action does not meet the goal.
A significant role of emotions in the processes of learning and memory formation. Any behavior act, being painted some emotion, for a long time leaves a trace in the CNS Training successfully only in that case when unpleasant emotion that accompanies any need, will end with a positive emotion reinforcements. First, it's internal needs. However, as individual development human behavior begin to define not only innate needs. The adoption of the decision and bring it in action precedes the analysis and synthesis of all situational stimuli, evaluating them in connection with the internal needs of the body. The result is that the emotions that formerly served" only primitive needs of the body, a person can contribute to satisfying the higher social motives.
So, based on the primary emotions is formed and more experience. In the end, all types of conduct of the body combined with a specific emotional activity. Upon learning and repeated reinforcement of the different motivations of a person acquires the ability to follow to achieve the goal not only negative emotion that accompanies the demand, but the idea of the positive emotions, that waits for addressing these needs. Thus, positive emotions begin to play in purposeful activities of a role even greater than negative emotions.
Finally, emotions is one of the means of information transfer. In this respect they are particularly important in animals. However, in humans, along with speech emotions play an important role as a means of communication, giving a speech expressiveness.