What is an erection?

The penis can be compared to a "sponge". Where the sponge is the cavernous bodies of your penis that fill with blood during an erection. The penis fills with blood under the action of nitric oxide. This blood creates internal pressure, which leads to the fact that the penis rises. The chain of action is: 1) Excitation in the head (brain) 2) Nitric oxide release locally 3) Guanosine activation 4) Relaxation of the muscles at the root of the penis 5) Filling with blood, the outflow veins narrow.