Vega literally mean urge or impulse. In physiology, Vega are the urges that occur naturally in the body to expel metabolic waste products like urine, feces, flatus etc. and as a reaction of the body at certain times such as belching, yawning, sleep etc. to ensure comfort. Urge is a strong impulse to do something urgently.
In disease pathology, the term vega means acute onset or episode of disease. Example Jwara vega, Apasmara vega