| 1 | It wasn't long before I had another erection. | |
| 2 | There have been reports of men having painful and sustained erections. | |
| 3 | These structures include erectile tissue, glands, muscles, blood vessels, and nerves. | |
| 4 | Hormone levels. Hormone imbalances, such as testosterone deficiency or too much of the hormone prolactin, can cause erectile dysfunction. | |
| 5 | Animal models have established that both sexual desire and erections arise from dopamine signals. |