A guy might think he knows his penis well – but does he? Sure, he knows a lot of the basics, like how to use that tool he’s got, or how to take care of it with good penis care, and how to protect his penis health through the use of a condom when having sex, or through being careful to choose the right partner. But there are some points of anatomy and physiology that help a man figure out how his penis works from the inside out. Here are a few.

Smoking Can Diminish Penis Size

Although it sounds like fearmongering from those who don’t like smoking, this is actually a proven fact. Think about the amount of blood a penis needs to expand to the size of a typical erection. Those blood vessels that facilitate that expansion must be in good shape. Smoking affects the vessels, clogging them up over time, so that they don’t perform as well. In fact, it’s common for heavy smokers to experience the loss of a few inches of penis length over time.

Lack of Use Can Diminish Penis Size, Too

Now this really does sound like fearmongering, but again, it’s true. When the penis skin expands during an erection, it keeps the tissue flexible. Those who don’t have as many erections will often have stiffer skin, which won’t be as flexible. The result is that the skin will not stretch as far as it could, leaving a man with an uncomfortable erection, or one that it definitely smaller than it used to be.

Part of the Penis Is Inside the Body

It’s obvious that part of the penis is outside the body, but where does it end? The tissue of the penis continues inside the body, but how far does it go? The answer to that is surprising: for most men, what’s inside the body is approximately as long as what’s outside the body. The extra tissue is necessary for stabilizing the penis during the motion of sexual activity.

So the next time someone wonders about penis size, they can rest assured that it’s bigger than they think. A man has, say, 5 inches on the outside? He’s got another 5 inside, for a total of 10 inches. (You’re welcome.)

Masturbation Often Causes Injury

A man might scoff at this idea, but it is true – for most men, at some point, masturbation will lead to some sort of injury. Perhaps it’s as simple as an injury caused by stroking too much, leading to abrasions and sores. Perhaps it’s using the wrong kind of lube and winding up with contact dermatitis. But often it’s a matter of holding the penis too tightly, thus doing damage to the blood vessels and delicate nerves in the skin. The loss of sensation that can result might take months to restore, assuming it can be restored at all.

The Penis Is Covered in Bacteria

Just like the rest of our skin, the penis is absolutely covered in bacteria. Although regular washing removes a great deal of it, some will always remain. These bacteria feed on dead skin cells, and sometimes on the sugar from urine, but they don’t really cause any problems for a healthy penis. It’s when something goes wrong that they show themselves. This usually happens when a man isn’t too clean down there, and the bacteria begin to feed on more dead skin cells than usual, thus leading to a fishy odor.

Maintaining Good Penis Health

There are many things about penis health that are a mystery, that scientists are slowly learning about as they study sexual health in general. But one thing is certain: good penis care should always look to moisturizing to help ensure supple, smooth skin. That’s where a good penis health oil (health professionals recommend Man 1 Man Oil, which has been clinically proven safe and mild for skin) comes into play. Look for an oil with shea butter and vitamin E, 2 powerhouses of moisture that work synergistically to improve the skin.