Nervous Regulation Tools A B Regulation controland cooradinationof all life activites Receptors structures that are sensitive to changes in the external and internal envieonment Effectors museles in which neurons are attached to neurons nerve cells impulse electronical message Stimulus a cahnge in internal and external envionment Receptors structures that are specialized to detect stimuli Dendrites l Fibers that detect stimuli and generate an impulse toward the cyton Terminal Branches l The ends of axons that secrete neurotransmitters Neurotransmitters l Chemicals secreted by the terminal branches that aid in the transmission of an impulse across the synapse Synapse l The gap between the terminal branches of 1 neuron and the dendrites of another neuron. Motor neuron carry impulses from brain and spinal cord toward the effectors Sensory neuron carry impulses from the receptors toward the spinal cord and brain reflex arc sends messages interneruuron impusis from one neuron to another.