During and after the teen years, the testes (testicles) make a steady supply of hormones, mostly testosterone. The testes also produce millions of sperm each day. Making finished sperm takes more than 3 months. Part of this happens as the newly made sperm travel through a 20-foot long tube to ripen. This tube (called the epididymus) forms a coil that sits on top of each testicle.
Just before orgasm, another tube takes the sperm into the body toward the prostate gland. The sperm are mixed with fluids that help nourish the sperm so they can live. During orgasm this mixture of fluid and sperm, called semen, comes out of the tip of the penis. The drawing below shows the male sex organs.
Hormones
Testosterone is the hormone that helps promote sex drive and erections. Men’s hormone levels vary, but most men have more testosterone than they need. A man with low testosterone may have trouble getting or keeping erections and may lose his desire for sex.
Male orgasm
A man’s orgasm has 2 stages.
The first stage is called emission. During that stage, semen is put near the top end of the tube that comes out through the penis (the urethra). A small valve above that point in the tube shuts to keep the semen from going up and back into the bladder. A man feels emission as “the point of no return,” when he knows he is about to have an orgasm.
The second stage of orgasm is ejaculation. It is controlled by the same nerves that carry pleasure signals when the penis is touched. These nerves cause the muscles around the base of the penis to squeeze in rhythm. This pushes the semen out of the penis. At the same time, messages of pleasure are sent to the man’s brain. This is sometimes called the climax.
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