How does an erection work?

Brain, nerves, blood vessels and hormones — explained simply.

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Arousal begins in the brain or through touch. Nerve signals tell blood vessels in the penis to relax, letting more blood flow in and stay there.

Hormones support the process, and mood, stress and attention matter a lot. Healthy erections depend partly on healthy blood flow.

Sources

• Erectile Dysfunction — NIDDK (U.S. National Institutes of Health)
• Erectile Dysfunction — MedlinePlus (U.S. National Library of Medicine)