Viagra is one of the best-known drugs of all time.
Nearly every adult in America has heard of the drug and can tell you what it does.
To understand how to make a penis-specific drug, think about the way blood flows in your body.
Your body has just one pump — the heart. But different parts of the body need different amounts of blood at different times. For example, if you’re running a marathon, your body needs to send more blood to your arm and leg muscles, and it may want to cut most of the blood flowing to the stomach (and other nonessential organs) in order to save oxygen for the legs.
What your body needs, in other words, is a set of valves that it can use to increase and decrease blood flow to certain parts of the body – and your brain needs a way to control them.
So what is the big deal about “the little blue pill”?
It’s simple: When it works as intended, Viagra causes a man who is sexually stimulated to get an erection.
How does Viagra do that? And why does Viagra work only if the man is sexually stimulated?
The mechanism that the body uses to open a valve in any part of the body is a simple little chemical machine:
- The brain sends a signal down a particular nerve fiber. This nerve fiber ends in a nerve cell in an artery, somewhere near the point where blood flow needs to change.
- These nerve cells — called nonadrenergic-noncholinergic, or NANC — produce nitric oxide and inject it into the blood and surrounding cells.
- The nitric oxide stimulates an enzyme (guanylate cyclase) in nearby cells that starts producing a chemical called cyclic guanosine monophosphate (cGMP).
- cGMP tells smooth muscles that line an artery to relax. When they relax, blood flow increases.
There is one final part to this chemical machine: Another enzyme, called phosphodiesterase(PDE), is deactivating the cGMP all the while.
cGMP is produced as long as the brain is sending messages down the nerve fibers in the artery. When the brain stops sending the signal, all of the cGMP goes away because PDE is deactivating it. This is how the brain turns valves on and off whenever it wants to.
For many people, talking about the penis is tough. This area of the body is considered private and isn’t discussed publicly (well, not in polite company). However, the penis is simply a part of the male anatomy designed to accomplish a task, and we’ll treat it that way here.
In the case of the penis, there are actually two tasks that it handles:
- releasing urine from the bladder, known as urination
- releasing sperm and seminal fluid from the prostate gland, known as ejaculation
Viagra helps with the second task: ejaculation.
When things are working properly, ejaculation is a three-step process:
- The man becomes sexually aroused.
- The penis responds by becoming erect.
- Stimulation of the penis causes ejaculation.
That sounds simple enough, but in many cases, step two doesn’t happen, making step three difficult or impossible. Although the man is stimulated, the penis doesn’t become erect.
To understand why, you need to understand the technology of an erection.
When you want to move nearly any part of your body, you do it using muscles. Whether you’re moving your fingers, toes, arms or legs, muscles do the work. Even when you stick your tongue out, you do it using muscles:
- You think about moving some part of your body.
- The appropriate muscles contract.
- That part of the body moves.
Muscles let you move your body voluntarily with precise control.
Did you Know?
- The first real breakthrough in the treatment of erectile dysfunction came in 1983. Prior to that time, it was thought that erectile dysfunction – the inability to achieve an erection – was primarily mental.
- That concept came crashing down at the 1983 American Urological Association meeting in Las Vegas when Dr. Giles Brindley injected his penis with the drug phentolamine. Following the injection, Brindley appeared on stage and dropped his pants to display one of the first drug-induced erections to the incredulous audience of urologists.
- The average male has four to eight spontaneous erections every night while he sleeps. They usually occur during the REM stage, when dreaming is most common.
- When a doctor wants to know whether a patient’s difficulty achieving an erection is due to physical or mental reasons, one way to find out is to fit the patient’s penis with a sensor and see whether or not the patient’s dream erections are working properly. If not, the problem is probably physical.
