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videos Ejaculating penis
So that one's erect. The brain and the spinal cord send messages back to the penis to cause ejaculation. The first step is called erection. Blood normally flows into these vascular chambers via both dorsal arteries and cavernosal arteries. Ejaculation semen.
Reproductive system introduction
Handsfree Over on the other side, on the erect side, there's another neuron, actually a different type of neuron, that actually sends a different signal to the arterials, and results in them opening up and allowing blood into the penis. Male ejaculation. Wikimedia category.