A JXUwMDJiJXUwMDA3JXUwMDFkJXUwMDA0JXUwMDE4JXUwMDE5JXUwMDE5JXUwMDA2 is a change in the JXUwMDNkJXUwMDBiJXUwMDE4JXUwMDFmJXUwMDFiJXUwMDFkJXUwMDAxJXUwMDAzJXUwMDA4JXUw MDBiJXUwMDFh of an organism.

Animals respond to stimuli in order to keep themselves in favourable JXUwMDNiJXUwMDBjJXUwMDAxJXUwMDBhJXUwMDBkJXUwMDFkJXUwMDFkJXUwMDA2JXUwMDAxJXUw MDFk .

The JXUwMDNiJXUwMDA2JXUwMDBiJXUwMDFhJXUwMDA2JXUwMDEzJXUwMDBk JXUwMDM2JXUwMDBiJXUwMDE3JXUwMDA0JXUwMDE5JXUwMDFhJXUwMDA2 JXUwMDJiJXUwMDBhJXUwMDBhJXUwMDA3JXUwMDExJXUwMDA4 (CNS) coordinates an animal’s responses using JXUwMDJiJXUwMDE2JXUwMDBiJXUwMDFkJXUwMDFjJXUwMDFkJXUwMDBi neurons carrying impulses from receptors to the CNS and motor neurons carrying impulses from the CNS to JXUwMDNkJXUwMDAzJXUwMDAwJXUwMDAzJXUwMDA2JXUwMDE3JXUwMDFiJXUwMDFkJXUwMDAx .

e.g. Light receptor cells are in the retina of the JXUwMDNkJXUwMDFjJXUwMDFj .
e.g. Hormone secreting cells are JXUwMDNkJXUwMDAzJXUwMDAwJXUwMDAzJXUwMDA2JXUwMDE3JXUwMDFiJXUwMDFkJXUwMDAx in glands .
e.g. Muscle cells are effectors in a JXUwMDM1JXUwMDE4JXUwMDA2JXUwMDEwJXUwMDBmJXUwMDA5 .

In the mammalian nervous system the CNS (brain and spinal cord) is connected to the body via the JXUwMDI4JXUwMDE1JXUwMDE3JXUwMDFiJXUwMDE5JXUwMDE4JXUwMDBkJXUwMDE3JXUwMDEzJXUw MDBk nervous system. (sensory and motor neurons).