system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how a penis can get erect, maintain proper circulation without increasing the blood pressure appreciably in the rest of the circulatory system?
gpt
The arteries leading into the penis dilate, resulting in an increased profusion of blood. The veins leading out of the penis are constricted by muscular action, restricting the ability of the blood to flow back out of the system into the body at large. This also explains in part how a priapism can be dangerous, as you can get oxygen-starved tissues.