Marcy and Jack dig into neurocardiology — the heart's own nervous system of more than fourteen thousand verified neurons, and why the famous forty-thousand figure doesn't check out — plus a two-minute listening-post morning practice. Read the paper: Potential clinical relevance of the 'little brain' on the mammalian heart (J. Andrew Armour, 2008, Experimental Physiology) — https://doi.org/10.1113/expphysiol.2007.041178