Compare, contrast, and explain the relationship among pacemaker potentials and contractile myocardial action potentials. describe how pacemaker potentials coordinate the heart rate. drawings or graphs may be appropriate.

There are so many examples for that in different areas, like NCzmPy2Cz experiment carried out in our lab recently.Here's one link: http://www.alfa-chemistry.com/nczmpy2cz-cas-2041519-51-9-item-294474.htm

the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus