<prompt> The mu u opoid receptor is responsible for the following effects all except:miosisbradycardiahypothermiabronchodialation  <response>: Ans. is d i.e., bronchodilation It is easy to pick the correct answer even if one knows nothing about opioid receptors, as morphine causes contraction of smooth muscle of bronchi.Action of morphine on the respiratory systemit depresses respiratory center by acting on m receptorsit causes bronchoconstriction by causing histamine release not bronchodilationOther actions of morphine mediated through m receptor -AnalgesiaRespiratory depression Mnemonic - Prime Minister CAREGITConstipationEuphoria -MiosisPhysical dependenceNote: morphine causes decrease in heart rate by its depressive action on vasomotor centre through m receptors 