<u><em>Internal and external stimulus in the body are detected by the receptors,</em></u> 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. <em><u>The response is the sent to the effector cells through the motor neuron where different actions are triggered.</u></em>
Receptors are specialized cells that can detect changes in the environment called stimuli and convert them to impulses.
<u>An effector refers to parts of the body generates response. These includes, muscles and glands.</u> Muscles may respond by either contracting or relaxing to aid a certain response, while glands would respond by releasing hormones in the blood.
An effector is a response for a particular stimulus. Effector can either oppose a particular stimulus or enhance it. This process can be useful for maintaining homeostasis. Homeostasis involves the maintainence of internal body temperature by the organism for sustainence of life. For example, while regulating body temperature, the heat or cold stimuli are detected by receptors in skin, which transfer information to brain and then to effectors, the effectors generates response in the form of bodily action. Effectors in the brain will activate those in blood vessels and sweat glands in response to heat and cold stimuli in regulating body heat or temperature.