Found this channel to be very accurate and helpful in many different areas as well as SEVERAL other people praising them for being the reason they passed their NCLEX.

Goes more in depth than our Basic book, but gives more connecting points to better understand how the Nervous System is involved in different types of Shock.

Dives into Polarization and Depolarization of the heart with animations as well as QRS complexes to better visualize what's occuring during contractions and relaxations of the myocardium.