Now, unfortunately, THIS is a subject that I can tell you WAY too much about. My husband has a rare condition called 'hypokalemic periodic paralysis' or 'HKPP'. He takes MASSIVE amounts of potassium daily and still has paralysis attacks - already done 2 this morning and almost made a hospital trip with HIM. He goes completely limp, is semi-conscious, can't swallow and I still have to manage to pour liquid potassium down him and get him to swallow it without going down his windpipe. If I can't get his potassium back up, eventually his heart will quit beating and his breathing will stop. This is NOT NORMAL - what I'm talking about here is a MUTANT gene condition.
The body runs on electricity just like your car/house. Potassium is one of the required minerals to make the electrical contact making each cell work thus making the muscles work. Remember, almost everything in the body is either a muscle of some type or controlled by a muscle. When the potassium is too low, the ligaments and tendons take over the 'holding' of things together and letting them move. Example - his head falls completely forward because his neck muscles can't hold it up. If he does lift it, he's using ligaments and tendons instead. Those aren't designed to be used that way and can tear away from the bone. I hold his head up all thru the attack (5 minutes to 4 hours) to support it. This works exactly the same with animals.
This link I'm providing is to a page about HKPP but will give you a better understanding of how potassium works:
http://www.hkpp.org/faq/hypokalemic_periodic_paralysis.html.
The biggest reason for low potassium in NORMAL living things is dehydration....
Hugs to All!
Lyresa and KT