Question

how do nervous tissue cause action

Answer 1

it generates an electric impulse in response to stimuli
the message is passed from the hair like substance at the head called dendrite and is passed to the body, axon from which it is further transmitted to the nerve endings and finally to the dendrite of the other neuron cell
 

Answer 2

Stimuli----------> Receptor organ---------->Affector---------->Spinal cord----------->Motor neuron----------->Effector-------->Response