[Factors of variation of heart rate].

Heart rate (HR), which participates in the short-term control of blood pressure and blood flow, depends on an intrinsic system and an extrinsic system via which the central nervous system processus and regulates the afferent stimuli of baroceptors and chemoreceptors. The situations responsible for short-term variations of HR include effort, the "white coat" effect, circadian rhythm, age, gender. The long-term maintenance of the HR level is dependent on nervous mechanisms, and haemodynamic and energetic conditions.