All are cardiovascular effects of parasympathetic stimulation except -
Ans. is 'c' i.e., Increased automaticity Effect of autonomic nervous system on hearto The SA node develops from structures on the right side of the embryo and the AV node from structures on the left. This is why right vagus (parasympathetic) is distributed primarily to SA node and the left vagus (parasympathetic) mainly to AV node. Similarly, the sympathetic innervation on the right side is distributed primarily to the SA node and the sympathetic innervation on the left side primarily to AV node,o Effects of ANS on cardiac physiology are as follow : - A) Parasympathetic (vagal) stimulationi) Negative chronotropic (decreased heart rate) : - Vagal stimulation cause decrease in slope (flattening) of prepotential (pacemaker potential) and therefore the time taken to reach the threshold levelis increased - Heart rate is decreased.ii) Negative dromotropic (decreased conduction).iii) Increased refractory period of all type of cardiac cells.B) Sympathetic stimulationi) Positive chronotropic (Increased heart rate):- Sympathetic stimulation increases the slope of phase 4 prepotential (pacemaker potential); therefore, time taken to reach the threshold is decreased and heart rate is increased.ii) Positive ionotropic (Increased contractility).iii) Positive dromotropic (Increased conduction velocity in conductive tissue).iv) Decreased in refractory period of all type of cardiac cells.v) Positive bathmotropic (Increased automaticity).
Decreased heart rate
Decreased conduction
Increased automaticity
Increased refractive period
Autonomic Nervous System