The Spark of Life: Electricity in the Human Body - Book Review
November 28, 2021
Ion Channels. Yup, ion channels. Electricity in the Human body revolves around ion channels and how voltage differences between the inner and outer part of the cell cause movement, or transmit information to the brain.
From the Back Cover
What happens during a heart attack? Can someone really die of fright? What is death, anyway? The answers to these questions lie in the electrical signals constantly traveling through our bodies, driving our every thought and action.
In The Spark of Life, acclaimed researcher Frances Ashcroft leads us from the facinating eighteenth-century experiments that inspired the classic novel Frankenstein to today's frontiers of biology. Drawing on incredible case studies, she explains how electrical activity is crucial for our well-being and describes how the latest research in cellular ion channels is yielding some of the most promising advances in medicine. With inimitable wit and a clear, fresh voice, Ashcroft provides a spectacular account of the body electric.
Details
- Author: Frances Ashcroft
- Published: 2012
- Publisher: W. W. Norton & Company
First Off, What is with the Online Synopsis?
Why is the synopsis available online different than the version on the back cover of the paperback? The synopsis you see above is straight from the back of the paper back version.
Ion Channels
Francis Ashcroft is scientist and professor of physiology at the University of Oxford, and a fellow at both Trinity College, Oxford and the Royal Society of London. Needless to say she is an expert in her field and talks about ion channels – which are proteins embedded in the membrane of a cell; some of which bring ions (such as Sodium, Potassium or Calcium) in, and some of which take out ions (like Potassium and Calcium).
This intake and outtake of ions produces a voltage differential between the inside and outside of the cell. The movement of these ions (ions are positively charged) creates an electrical current that powers motion (as is the case with the muscles including our heart), or transmitting signals to the brain; which, in turn, tells us what the signal is (for example, if we touched something that was hot, or if we saw or smelled something).
A History Lesson in Electricity
Ashcroft goes into the history of electricity - from the earliest static electricity experiments with amber and a cloth to the most recent advancements in the field of electricity.
This background information was needed as it sets the stage for the subject matter, but at some points it's a little dull, and we are left wondering if we're reading a book on the human body, or a layman's book on electricity. I'm glad I had the paperback version and not the eBook version or I would have been lost (non-fiction, I find, is harder to read electronically if the author goes off on tangents).
Ashcroft talks about the first voltaic cells, experimentation on the leg muscles of frogs, and the debate between DC and AC current. It's interesting that Edison invented the electric chair to prove how dangerous AC current was (he was a proponent of DC current of which he had invested a considerable sum).
Full of Useful Information
Glossing over the boring parts, Ashcroft's book has a lot of really good information about electricity in the human body. Below is one example:
"Maintaining the ion gradients is expensive, for electricity does not come cheap, even when we produce it ourselves. It is extraordinary to think that about a third of the oxygen we breathe and half of the food we eat is used to maintain the ion concentration gradients across our cell membranes.". (page 40)
Okay, granted there are trillions of cells in the human body, so yes, the quote above makes sense, but you don't really think about it until it's actually mentioned.
Hear, Hear!
The chapter on the ear was good. I learned how the tiny hairs within the ear produce sound waves, which are passed from the air to fluid filled canals in the inner ear. Sensory cells in the fluid convert the sound waves to electrical impulses via – you guessed it – ion channels! This signal is forwarded to the brain which tells us what we heard.
The Beat Goes On
The chapter on the heart was also quite good. Ashcroft explains how electricity causes the heart to beat. This is caused by a special type of cardiac cell called the pacemaker cell, which uses a Sodium ion channel to generate a current. This current is transmitted incredibly fast causing a "beat" which pumps oxygenated blood to the arteries and deoxygenated blood to the lungs.
The beat isn't always regular, and sometimes goes into fibrillation (a case where the electrical signal is not synchronized and the heart can't beat properly). In this case a defibrillator literally stops the heart. For reasons still unknown, the heart restarts and this typically causes the electrical signal to be synchronized so that the heart beats properly.
Did I Like It?
Overall, I did like it, but did not completely enjoy it.
As I mentioned above, the book did drag on in some parts where the author went further away from talking about the human body that I would have liked. This left me reading about Eels, electric rays and how some of these were obtained for experimentation (all I have to say is poor horses).
It felt like there was a lot of padding added in. Again, to each their own — while I like zoology, if I pick up a book on the human body, I'd like to read more about human anatomy and physiology. A shark's (in this case the Gymnarchus) sensory electric field, while super interesting, is zoology and we don't use electricity in that way.
