In heart and intestine, sympathetics and parasympathetics act on same effector cell for antagonist response. In eye, sympathetics act by controlling radial muscle of eye. If contract radial muscle pupil get larger . If contract sphincter muscles pupil get smaller . In Tandem Parasympathetics gives copious watery salivary secretion.
Sympathetic activation gives thick viscous secretion .
It varies minute to minute and from organ to organ . Sympathoadrenal system often acts as a unit to facilitate fight or flight. Activation of sympathetic nervous system increases blood pressure, increases heart rate, blood goes to skeletal muscle, blood vessel dilate, pupils dilate, and bronchioles dilate . In a controlled environment and in the absence of stress, sympathetics not needed for life . It is organized for discrete activation of localized target organ.