How does erection work and what are the physiological processes involved in achieving and maintaining it?

An erection is a complex physiological process that involves the nervous system, blood vessels, and hormones. When a man becomes sexually aroused, the brain sends signals to the nerves in the penis, causing the blood vessels to relax and dilate. This allows more blood to flow into the penis, filling the spongy tissue called the corpora cavernosa. As the penis fills with blood, it becomes erect and hard. To maintain the erection, the blood flow is regulated by the release of hormones and the contraction of muscles in the penis. Once sexual stimulation ends, the blood vessels constrict, allowing the blood to leave the penis and the erection to subside.