The sympathetic and parasympathetic systems exert functionally opposite influences on the following parameters except:
Heart rate
Atrial refractory period
Pupil diameter
Intestinal motility
Ans. B. Atrial refractory periodMost organ receive dual innervation by both SNS and PNS. The level of activity of an organ at a given moment is the sum of sympathetic and parasympathetic tone. However, refractory period of atrial fibers is decreased by sympathetic as well as parasympathetic influences.OrganSNSPNSHeartIncreases HR, ContractionDecreases HRLungBronchodilationBronchoconstrictionGITDecreased motility, Contraction of sphinctersIncreased muscle motilityRelaxation of sphinctersBlood vesselContraction in cutaneous and splanchnic BV, Relaxation in skeletal muscle BVNo direct effect on BV*.Dilation in coronary BV via releases of EDRF(NO)EyeMydriasisMiosis and accommodation for near visionBladderUrinary Retention (contraction of sphincter)Voiding (Contraction of detrusor; relaxation of trigone)GenitaliaEjaculationErection
A.N.S.