ظ is emphatic ذ, not emphatic ز.ح ص ض ط ظ ق I think are the Arabic letters considered emphatic. They are considered "saturated" or emphatic (heavier or thicker perhaps?) variants of the letters ه س د ت ز ك respectively.
I am (currently) out of discussion but probably by linguistic approach some people try to make the issue fall inside another branch of science. or maybe try to explain by intersectional comprehensions. anyway, what I will say is that , I remember from some courses at MSc program, pharyngs and laryngs are parts of respiratory system.