$\begin{array}{llll}& \text{ Column-I }& & \text{ Column-Il }\\ \text{ a. }& \begin{array}{l}\text{ Visceral }\\ \text{ pericardium }\end{array}& \text{ (i) }& \begin{array}{l}\text{ Pace-setter of the }\\ \text{ heart }\end{array}\\ \text{ b. }& \text{ Sino-atrial node }& \text{ (ii) }& \begin{array}{l}\text{ Outer pericardial }\\ \text{ membrane }\end{array}\\ \text{ c. }& \begin{array}{l}\text{ Parietal }\\ \text{ pericardium }\end{array}& \text{ (iii) }& \begin{array}{l}\text{ Pace-maker of the }\\ \text{ heart }\end{array}\\ \text{ d. }& \begin{array}{l}\text{ Atrio-ventricular }\\ \text{ node }\end{array}& \text{ (iv) }& \begin{array}{l}\text{ Inner pericardial }\\ \text{ membrane }\end{array}\end{array}$
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Heart is protected by double walled membranous bag, called pericardium, enclosing the pericardial fluid. The inner surface of the pericardium is lined by the outer (parietal) layer of serous pericardium. The inner (visceral) layer of the serous pericardium lines the outer surface of the heart itself.  
AV (atrioventricular) node is a mass of modified heart muscle situated in the lower middle part of the right atrium. It receives the impulse to contract from the SA node(pace maker of heart) via the atria and transmits it through the atrioventricular bundles to the ventricles. AV node is called the pace setter.