5. What are the structural and functional differences between cardiac myocardial (contractile) cells and autorhythmic cells? What are intercalated discs and what is their primary function? 6. Review the concept of excitation-contraction coupling. Compare excitation-contraction coupling for a skeletal muscle fiber and a cardiac myocardial contractile cell. Why does "excitation" look different for myocardial cells? Pay attention to the types of channels found in myocardial cells and ion flux, specifically the role of calcium.

Subduction zones form when an oceanic plate collides with another oceanic plate or continental plate. the continental crust is lighter and less dense than oceanic crust. continental crust's density is approximately 2.7 grams per cubic centimeter. oceanic crust is thinner and the average density is about 3.3 cubic centimeters. when the two crustal plates converge the oceanic plate always bends and subducts beneath a continental plate. once the oceanic crust subjects, the rocks are subjected to changes in heat and pressure. because of this, we would expect to find rocks in the area of a subduction. a) clastic b) igneous c) metamorphic d) sedimentary