The response of an effector is to provide a counter stimulus to neurons to transmit a negative feedback impulse to maintain homeostasis to decrease the external stimulus

Answer;

To maintain homeostasis

Explanation;Internal and external stimulus in the body are detected by the receptors, which then sends signals to the central nervous system via sensory neurons, where the signals are interpreted and a response is coordinated by the brain. The response is the sent to the effector cells through the motor neuron where different actions are triggered.Receptors are specialized cells that can detect changes in the environment called stimuli and convert them to impulses.An effector refers to parts of the body generates response. These includes, muscles and glands. Muscles may respond by either contracting or relaxing to aid a certain response, while glands would respond by releasing hormones in the blood.

That would be a working theory.