erects

Erections, or penile erections, are physiological events in which the penis becomes rigid due to blood engorgement. They are typically triggered by sexual arousal and can also occur spontaneously during sleep. Successful erections depend on an integrated function of the nervous system, blood vessels, hormones, and psychological factors.

Anatomy and mechanism: The two corpora cavernosa and the corpus spongiosum fill with blood during an erection. The tunica albuginea constrains the engorgement and helps impede venous outflow. Parasympathetic signaling releases nitric oxide, relaxing smooth muscle in penile arteries and increasing arterial inflow. This arterial influx, combined with reduced venous drainage, produces tumescence and rigidity. When arousal ends, sympathetic activity causes smooth muscle contraction and venous outflow to resume, returning the penis to a flaccid state.

Development and variety: Erections begin at puberty and reflect hormonal status, cardiovascular health, and neural integrity. They can be affected by age-related changes, medical conditions, medications, and lifestyle.

Clinical notes: Erectile dysfunction is the persistent inability to achieve or maintain an erection sufficient for intercourse. Priapism is a prolonged, often painful erection that requires urgent medical evaluation.

Diagnosis and management: Evaluation includes history, physical examination, and sometimes testing. Treatments vary by cause and may include lifestyle changes, oral medications (PDE5 inhibitors), vacuum devices, intracavernosal injections, or penile implants. Managing underlying conditions such as diabetes, hypertension, and obesity, along with psychological support when indicated, can improve outcomes.