The Heart Is The Center Of The Cardiovascular System. Whereas, The Term Cardio Refers To The Heart, The Term Vascular Refers To Blood Vessels. The Heart Acts As A Pump, And Maintains A Constant Circulation Of Blood Throughout The Body. As Blood Flows Through Body Tissues, Nutrients And Oxygen Move From The Blood In To Interstitial Fluid And Then Into Cells. At The Same Time The Blood Picks Up Wastes, Carbondioxide, And Heat. Even At Rest, Our Heart Pumps 30 Times Its Own Weight Each Minute, About 5 Liters To The Lungs And The Same Volume To The Rest Of The Body. The Physiological Oscillators Produce Oscillations, In The Form Of Stable, Closed Trajectory Called A Limit Cycle. These Oscillations Exhibit The Phenomenon Of Frequency Entrainment Or Phase Locking. These Are Analyzed By Presenting Vanderpol Oscillator. Vanderpol Oscillator Is A Non-Linear Oscillator. In The Non-Limit Cycle Oscillator, External Disturbance Move The Phase Trajectory To Different Orbit Around The Centre And Will Not Come To Original  Point, Where As In Limit Cycle Oscillator, The Phase Trajectory Returns To Its Original Location. When Vander Pol Oscillator Is Driven By The External Frequency, Which Is Different With Natural Frequency Of The Oscillator, Then The Resultant Output Is Mixture Of Components That Result From The Interaction Of The Driving Periodicity On Natural Oscillations. If The External Frequency Is Equal To Natural Frequency Of Vendor Pol Oscillator, Then Nonlinear System Will Adopt The External Frequency. The Time Courses Of Oscillatory Activity Of Heart And Phase Trajectories Are Generated By Vanderpol Model By Using The Simulink. The Response Of Vander Pol Oscillator For Various External Frequencies Is Also Obtained.