Men’s sex organ is the penis, through which the male body discharges semen for reproduction. It is also the organ through which the body ejects urine as waste.
A penis becomes erect when a man becomes aroused sexually. Nerves compel blood to rush into the penis, particularly to a columnar tissue called the corpus cavernosum. Only then would the penis “harden” or undergo an erection.
Blood also fills up the corpus spongiosum, a spongy tissue in the penis which encompasses the urethra, the passageway for urine. Filled with blood, the corpus spongiosum keeps the urethra open even as the penis stays erect.
