What Is Erection? How Does It Happen?
Physiologically, erection is triggered by the parasympathetic division of the autonomic nervous system (ANS), causing nitric oxide (a vasodilator) levels to rise in the trabecular arteries and smooth muscle of the penis. The arteries dilate causing the corpora cavernosa of the penis (and to a lesser extent the corpora spongiosum) to fill with blood; simultaneously the ischiocavernosus and bulbospongiosus muscles compress the veins of the corpora cavernosa restricting the egress and circulation of this blood. Erection subsides when parasympathetic activity reduces to baseline. Was that too complicated?
Whats Is Erection in A Simplified Version?
Three steps take place to produce and sustain an erection:
The first step is sexual arousal, which men obtain from the senses of sight, touch, hearing and smell, and from thoughts.
Nervous System Response
The brain communicates the sexual excitation to the body’s nervous system, which activates increased blood flow to the penis.
Blood Vessel Response
A relaxing action occurs in the blood vessels that supply the penis, allowing more blood to flow into the shafts that produce the erection.
If something affects any of these three factors — arousal, nervous system response or circulatory system response — or the delicate balance among them, erectile dysfunction can result.