In the case of the baro-reflex, these components are as follows:
Sensor: the baro-receptors, located in the internal carotid arteries (located in the carotid sinus) and along the aortic arch. These are stretch sensors. When they are stretched (because of higher blood pressure), they will send more action potentials to the CNS. If the blood pressure is decreased, then the firing frequency is decreased. Therefore, they ‘sense’ the blood pressure.