Sentence:  Moreover , the dominance in parasympathetic action ( with reciprocal inhibition of the sympathetic ) at the hypothalamic level induces , by its peripheral action , the autonomic symptoms of sleep and , by its action on the cortex , a lessening in the reactivity of the sensory and motor <WSD>apparatus</WSD> of the somatic nervous system . 
Meaning of the word marked with <WSD> tags:  equipment designed to serve a specific function