A cardiac physiologist's opinion about the heart-testicles proposed in Just The Tips,
by Matt Fraction and Chip Zdarsky; Image Comics
Just The Tips is a book of sex advice from the creators of the comic Sex Criminals. It is pretty funny and insightful in a warped and not particularly helpful way. It is an all around good time if you are a mature reader who has a sense of humour about human sexuality. (If not, please do not read this book.)
The thing is, as a professional heart Scientist I feel like the writers of Just The Tips are misleading the public, and I feel that it is my duty to debunk their ideas before someone's testicles are injured!
There will be *SPOILERS* for Just The Tips in this post.
My specific grief is with the Genitals of the Future (Probably) feature of Just The Tips. In it, the authors suggest that Balls should be inside the human body to avoid soccer injuries and like, sitting on them. Now, as sex advisers, Mr. Fraction and Mr. Zdarsky are above reproach; Mr. Fraction has two children so statistically has to have done it at least a couple times and Mr. Zdarsky, being Canadian, likely survives the winter on a hardy diet of maple syrup, bannock, and heat giving intercourse. So Sexperts. But clearly these visionaries don't know enough about scrotal physiology or cardiac biology to be ball transplant surgeons.
Problem 1: Intemperate Balls. On principle moving testicles inside the body makes a lot of sense; it seems like the natural solution to prevent slamming your drongles in doors. However, testicles exist outside of the body for a reason: spermatogenesis, the process of generating the male gamete, is super sensitive to temperature. For the most efficient results, balls need to be kept ~2 degrees celsius below body temperature and maintained there. The temperature regulation is so critical that scrotums have the ability to sag and contract at different temperatures. Moreover, the wrinkles on the skin of the scrotum exist to increase surface area to cool balls. There is literally a special layer of smooth muscle whose sole purpose is to control the wrinkliness of balls. (Corollary: some human almost certainly devoted decades of their life to understanding how the dartos fascia controls ball wrinkles.) So basically moving human balls inside the body cavity is bad for sperm making.
Problem 2: Paradoxical Perfusion. But maybe you don't care about the sperm killing effects of body heat. Maybe that's a perk for you. Well, the heart is still a bad place for the balls! And the first reason is kind of counter-intuitive. The heart's job is to pump nutrient rich blood through the lungs to oxygenate it and then pump it everywhere else in the body. The ultimate goal here is to maintain a constant flow of blood through the tissues to give cells the nutrients and gasses they need as metabolic fuel and to clear away all of the toxic waste products of producing energy. A well perfused tissue, one that has a steady, consistent flow of blood, will be able to do this effectively. Here's the problem: the heart is one of the worst perfused tissues in the body, it has terrible blood flow. Which is crazy, right?! While the heart has first crack at the most-oxygentaed and most-nutrient rich blood (the cardiac arteries branch off the base of the aorta right where it leaves the heart), blood has a really hard time getting into the heart. This is because every time the heart contracts it actually crushes all of its blood vessels which cuts off the flow of blood into itself. So every time your heart beats to send blood everywhere else in the body, it's cutting off its own supply. So, the harder your heart works, the more it starves itself of oxygen and fuel. Which, as you can imagine, is pretty tough on your heart. Now imagine if your balls (if you are a ball-haver) are attached to your heart like in Just The Tips, sharing that terrible blood supply! It would be really bad for testicles!
Problem 3: The Heart Of Darkness. Okay, so maybe you think saving your balls from a non-consensual walloping is worth low sperm counts and oxygen starved balls. Well, the trouble is that balls attached to the heart, like what is portrayed in Just The Tips, wouldn't protect you from sacking your balls (again if you are a ball-haver). We all like to think of organs as modules plugged into the body like components in a high end robot. But the truth is that organs aren't really welded in place and have some freedom to move around inside the body cavity. It's pretty disgusting if you think about it. This is especially true of the organs in the chest cavity, which all kind of hang in the open space of the chest. Both the lungs and the heart are attached to the top of the chest cavity where the airway and aorta leave the space. They literally hang in your chest. Now, normally the lungs are pretty inflated, and fill most of the chest cavity with the heart beating inside their cushiony embrace. That said, the heart is pumping, contracting, and shaking in there, bumping against the lungs. Which, you know, is fine for a tough muscley heart. But for a pair of balls hanging off the outside of the heart this would be constant shaking, jostling, and squishing against the lungs. Basically, the balls would be permanently sacked at an average rate of once every second if they were on the heart. Which seems a poor solution to potential exterior sackage.
So, despite Mr. Fraction and Mr. Zdarsky's expertise as sex advisors, their proposal to mount testicles to the outside of the heart is a poor one.
Post by Michael Bround, PhD Candidate
Just The Tips Is A Good Book, I Guess
So I Read Sex Criminals Vol. 1
Deep Sequencing: Sex Criminals and adult sex portrayals
Sound Advice: Sex Criminals