The effector is a muscle or organ or gland that receives an impulse from the brain or the spinal cord produces a response to a stimulus. For example- Glands releasing hormones into the blood. The effectors are two types motor effectors and secretory effectors.

The nervous system is the most complex system that co-ordinates and transmits signals between different body parts. The central nervous system and peripheral nervous system are two main parts of the nervous system. The basic unit of the nervous system is neurons. Neurons are also known as nerve cells. Neuron comprises main three parts — cell body or soma, axon, and dendrites. Sensory, motor, and interneurons are three different types of neurons.

Motor nerves are those nerves that carry impulses from the brain or the spinal cord to the muscles or glands. Only motor fibres are present in these nerves. Nerves to the muscles of the eyeball are an example of this nerve.

A nerve is composed of a bundle of fibres that are surrounded by layers of tissue and fat and present throughout the body. Mixed nerves are those nerves that carry both the sensory and motor nerves. Electrical impulses are transformed from the central nervous system to the muscles of the body. They contain both sensory and motor fibres.

Reflex action is an involuntary action in response to a stimulus that is controlled by the spinal cord together with the medulla oblongata. The nerve pathway that takes place in a reflex action is called a reflex arc. Autonomic and somatic are the two types of reflex arcs. Some important components of reflex arc are receptor organs, sensory neurons, nerve centre, interneurons, motor neurons, and effectors.