Reddit reviews The Spark of Life: Electricity in the Human Body

What level?

• Pre-university: https://www.khanacademy.org/science/biology
  
  
• University (if you already feel overwhelmed this is probably too much): https://www.edx.org/course/mitx/mitx-7-00x-introduction-biology-secret-1768 (very good! - and it does not matter whether the course is "running" or not, videos and quiz questions are available, that "certificate" such sites offer is rubbish, and if you can only learn with time pressure... well, you should change that first and learn to be able to work well also when nobody is sitting there with a clock pressuring you)
  
  
• You can also check out saylor.org, coursera.org and similar sites - they have various biology courses too
  
  
• Search Youtube and Google. Great resources for centuries of learning. For example, the 1st link I found was this.
  
  
  GREAT books, teach you university level insights but in a leisurely way. Maker no mistake, don't look down on such books just because they are written to be understood by lots of average people! Because in reality this stuff IS easy, only the teaching at universities really sucks very often. They can afford to not be nearly as good at explaining as those authors because you as a student are expected to do much more work on your own.
  
  
• Everything from biochemist Nick Lane
  
  
• The Spark of Life - probably the best book to understand electricity in our bodies
  
  
• Free textbook: https://openstaxcollege.org/textbooks/biology