The receptor cells of nervous system sense the changes in internal and external environment and send the information to the central nervous system (brain and spinal cord). The brain process the information and commands the muscles or effector organs to carry out required processes or functions under prevailing conditions. This makes the organisms to respond to the changes in internal and external environment.
Exo is spitting big things out. endo is pulling big things in. diffusion is molecules moving from an area of high concentration to an area of low concentration until it is balanced
