An apparatus mountable on a wearers wrist includes a housing having at front portion and an opposite a back portion. The back portion is wearably positionable in contact with the wearers wrist. The apparatus includes a PPG circuit for generating a PPG signal. The PPG circuit includes a light source and a photosensor on the housing back portion. The PPG signal may be used to continuously determine the wearers a pulse rate. The PPG signal may also be used in combination with an ECG signal to determine the wearers instantaneous blood pressure. The ECG signal may also be used to determine the wears heart rate. The ECG signal may be generated with an electrode mounted on the back of the housing and another electrode mounted on another portion of the housing, such as the back or one or more of the sides.
