An erection is a complex event that requires the interaction of the brain, nerves, hormones, and blood vessels. This process is separate from ejaculation and orgasm, both of which can occur without an erect penis.
The shaft of the normal penis consists of two erectile bodies, each called the corpus cavernosum,, which begin at the pelvic bone and extend to just below the head of the penis. They are spongy tissue made up of smooth muscle and blood vessels. The male hormone testosterone, which is secreted by the testicles, controls the function of the penis and a man's sex drive.
The brain starts the changes that will produce an erection.
- As a result of psychological or physical stimulation, the brain sends messages through the nervous system to the penis.
- These messages relax the smooth muscles in the blood vessel walls of the corpus cavernosum, causing them to open wider.
- When this happens, more blood flows through the vessels, filling the corpus cavernosum.
- At the same time, the veins that carry blood away from the penis shut down, causing an increase in blood pressure in the penis.
- The blood that is trapped within the corpus cavernosum causes the penis to become hard and erect.
What Makes Erection Fail?
Anything that interferes with this chain of events - either by reducing the blood flow to the penis or increasing the blood flow out of it - can cause erectile dysfunction. Fear, anxiety, anger, or any other strong emotion can interrupt the signal from the brain. An illness or physical condition can also impair erections if it interferes with this chain of events.
The Normal Changes As A Man Ages
Although sexual activity normally continues throughout a man's lifetime, his reactions take longer as he ages. He may need more stimulation to get an erection. He may take longer to climax, and he may need to wait longer before he can get another erection.
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