What are the series of events in the SA nodal cells that directly cause autorhythmic contraction of cardiac muscle cells

Acceleration is a direct result of a.) balanced forces b.) unbalanced forces c.) gravity d.) velocity hurry!

What controls activities within a eukaryotic cell?

The small molecule cyclic amp (camp) takes about 0.2 second to diffuse 10 μm, on average, in a cell. suppose that camp is produced near the plasma membrane on one end of the cell; how long will it take for this camp to diffuse through the cytosol and reach the opposite end of a very large cell, on average? assume that the cell is 200 μm in diameter.