chapter 11 Tools A B Regulation control of the coordiation Recepters changes in the external and internal environment Neurons basic unit of structure Effectors muscles or glands in which neurons are attached to Dendrites l Fibers that detect stimuli and generate an impulse Cyton Known as the cell body Axon impulse away from the cyton Terminal Branches ends of axons Synapse gap between the terminal branches Neurotransmitters l Chemicals secreted by the terminal branches Hydra impulses travel in all directions across a nerve net