Tiz's Chapter 11 Game Tools A B Regulation control and coordination Receptors sensitive to changes in the external and internal environment Neurons basic unit of structure and function in the nervous system Effectors Are muscles or glands in which neurons are attached to Impulses electrochemical message Stimulus is a change in the external or internal environment which initiates an impulse Dendrites Fibers that detect stimuli and generate an impulse toward the cyton Cyton Known as the cell body, Contains the nucleus of the neuron Axon A fiber that transmits the impulse away from the cyton and towards the terminal branches Synapse The gap between the terminal branches Neurotransmitters Chemicals secreted by the terminal branches that aid in the transmission of an impulse across the synapse Hydra Contains no brain or control center, so impulses travel in all directions across a nerve net Sensory neuron Carry impulses from the receptors toward the spinal cord and brain Interneuron Relay Impulses from one neuron to another Motor neuron Carry impulses from brain and spinal cord toward the effectors