Which of the following causes increase in conduction velocity of impulse through hea ?

Ans. is 'c' i.e., Sympathetic stimulationEffects of sympathetic stimulation are :i) Hea :- positive chronotropic (1' hea rate), ii) Positive ionotropic (1' contractility), iii) Positive dromotropic (1' conduction velocity), iv) Positive bathmotropic (increased automaticity), v) Decreased refractory period in all cardiac cells.ii) Vasoconstriction :- T total peripheral resistance (due to aeriolar constriction), venous capacitance (due to venoconstriction)iii) Increased stroke volume, cardiac output and BP.Effects of parasympathetic stimulation are :?i) Negative chronotropic (decreased hea rate) : - Vagal stimulation cause decrease in slope (flattening) of prepotential (pacemaker potential) and therefore the time taken to reach the threshold levelis increased --> Hea rate is decreased.ii) Negative dromotropic (decreased conduction).iii) Increased refractory period of all type of cardiac cells.