Question

PART 1: A physiologic explanation for the observed effect of exercise on heart rate would be the following: (select the correct bold-faced options)

Exercise-induced ["parasympathetic", "sympathetic"] stimulation to the ["autorhythmic", "contractile"] cells of the SA node ["increases", "decreases"] the permeability of the muscle cell membrane to ["potassium", "calcium", "sodium", "both calcium and sodium"] ions, bringing the membrane to threshold at a more rapid pace.

PART 2: A physiologic explanation for the observed effect of exercise on PQ interval would be the following: (select the correct bold-faced options)

Increased ["sympathetic", "parasympathetic"] stimulation ["increases", "decreases"] the excitability of the AV node and thereby ["increases", "decreases"] the length of the AV node ["threshold", "delay"].         .

Answer 1