If you don't know what an erection is, why would you put it in the mens sexual health section?

Maybe the question was supposed to be read as, "Physically, what happens to cause an erection?" The question could be read to mean that, and I am trying to give the Beginner a little slack before ripping his head off (although I think that it was probably a joke question anyway) For the record, I'll answer the "possible" question... Erections are caused by the flow of blood into the three chambers of the penis. The corpora cavernosa are two columns of spongy tissue that make up 90 percent of the erectile tissue of the penis. The corpus spongiosum surround the urethra and holds only about 10 percent of the blood present in the penis during erection. During arousal, the smooth muscles lining the veins of the arteries begin to relax. This relaxation causes blood to flow in. The veins of the penis begin to constrict; thus, blood can get in much more easily then it can out. The penis can hold 10 times the amount of blood when it is erect as opposed to when it is not erect. After orgasm, the veins and arteries return to normal and the blood flow returns to normal. Prostate cancer treatments can affect the flow of blood into the penis. Prostatectomy has been known to divert the flow of blood into the penis while radiation treatment has been known to cause arteriosclerosis, which is the hardening of the arteries. An erection begins with arousal. The brain detects the body becoming sexually aroused and transmits a message along the NANC neuron to tell the body to begin creating an erection. NANC stands of nonadrenergic, noncholinergic and uses nitric oxide to transmit the message. Once the nitric oxide reaches the neurovascular nerve bundles that hug the prostate gland, an enzyme called guanosine cyclase is released. An enzyme is like a biological catalyst; it is a specially folded protein that fits only into one substrate, like a key fits into only one lock. A substrate is the compound that the enzyme will change. The substrate for guanylate cyclase is called GTP or guanosine triphosphate. The guanosine cyclase changes the GTP into cGMP. cGMP causes the smooth muscles lining the arterial walls of the penis to relax. cGMP, however, is broken down by a second enzyme called phosphodiesterase type 5 or PDE 5. PDE 5 turns cGMP back into guanosine triphosphate or GTP to cause the arterial walls to not relax and decreasing the blood flow into the penis. The chemical cycle is started by the introduction of nitric oxide. The cycle begins with enzyme guanosine cyclase changing GTP into cGMP. The enzyme finishes when enzyme PDE 5 turns cGMP back into GTP. How about that for making lemonade out of a lemon question??

A political contest in Japan!

I find it rather worrying that this kind of question is asked . It is so difficult to know how to reply when we have no idea of the age of the person asking the question. I have a feeling this is a very young person. In many cases we give answers that a parent may not feel their child is ready to receive

You should ask your parents. It's when you get sexually aroused by a girl and blood flows to the penis and it stands up and becomes longer, larger, and firmer