A coordinated response means the right effectors act together, at the right time, in a way that suits the stimulus. The nervous system can do this because of four features.
- It reaches all parts of the body, so every receptor and every effector can be connected to the CNS.
- It has many links. Neurones meet at huge numbers of synapses, so one impulse can pass to several neurones.
- It has different sensory receptors, which detect light, sound, touch, temperature and chemicals.
- The CNS can coordinate responses. It receives information from the different receptors, processes it and then sends impulses to the effectors that are needed.
Catching a ball shows all four working together. Receptors in your eyes detect the ball. Impulses travel to the CNS, which compares the information and sends impulses to several muscles in your arm, hand and legs. Because of the many links, the muscles contract in the right order and at the right time. Without coordination the muscles would contract at random and you would miss the ball.