Most people find it hard to talking to others about the private parts of the human body, whether it is the female vagina or the male penis. Since these are considered private parts, discussing them publicly will make anyone uncomfortable, particularly with well-mannered people. It is likely that most people are comfortable talking about these things is with their friends. The thing is, if you are going to talk about them in an anatomical way and not in an erotic way, then it should be fine in many ways.
The Human Penis
The human penis actually has 2 main functions – the release of urine during urination and the release of sperm for reproduction during sexual intercourse. For the release of urine, the urinary bladder takes charge and pumps out the urine down the urethra and out of the penis. For the release of sperm, a man needs to be sexually stimulated to have an erect penis and must have continuous sexual stimulation to cause an ejaculation so sperm can be released.
One unique thing about the penis is that it uses the same tube for the passage of both urine and semen. Even if that is the case, a man can release only one fluid at a time and never both at the same time. This is because the urethra only allows urine to pass with the penis is limp and semen to pass when the penis is erect. This simple yet effective mechanism of the penis allows it perform dual purposes.
For the release of sperm, getting an erection is a prerequisite because sperm will not be released unless the penis is erect. When a man becomes sexually stimulated but cannot get his penis to become erect, he may be suffering from a condition called erectile dysfunction.
When we move any parts of our body, we always do it with muscles. Even with the simplest wink, nod, or tongue movement, all these movements are made using corresponding muscles. The thing about muscles is that they allow you to do things voluntarily and have much more control over it. The penis, however, is completely different. In order to make the penis erect, not a single muscle contraction is used. This is because the penis uses blood pressure to make the penis hard and erect.
The simplest explanation on how the penis becomes erect is to think of the bladders as a balloon. When a balloon is filled with air and inflated, it turns from a limp piece of rubber into something bigger, erect, and harder. This is the same with the penis. However, with the case of the penis, it is blood that fills the cavity making it harder and more erect. The cavity that is being filled with blood is called corpus cavernosum and they are two-tubes that arteries pump blood into during an erection. When the penis is limp, it means that these two cavities are devoid of pressurized blood.
When the penis is limp, the smooth muscles surrounding the corpus cavernosum constricts the cavity so blood is not pumped through. However, during sexual stimulation, this smooth muscle becomes relaxed freeing the corpus cavernosum of constriction and thus allowing blood to be pumped through so the penis can become erect.