Ryan is a 30-year-old man who recently made the decision to talk with his doctor about a somewhat sensitive issue. He just celebrated his third anniversary with his wife, and they have started talking seriously about having kids. Though he knows this is a big step, Ryan has always wanted kids, and he feels like he is in a great place in life to start a family. As Ryan tells his doctor, the problem is that he sometimes gets a little anxious, which prevents him from performing sexually. He says even a little stress about work can prevent him from getting aroused. While his wife is sympathetic to this issue, Ryan doesn't want it to get in the way of conceiving a child.

Based on a few Internet searches, Ryan says he thinks he has the solution to his problems. He suggests to his doctor that testosterone injections would be a great treatment for his issues with arousal. He says, since testosterone is the "male sex hormone," he thinks it would additionally help him conceive a child by raising his sperm count. Ryan's doctor tells him there are a number of potentially helpful pharmaceutical and nonpharmaceutical options they can discuss, but testosterone is probably not the best choice. He tells Ryan some doctors have actually experimented with testosterone as a contraceptive drug, since it greatly reduces sperm count for most men!

Questions

1. Provide a physiological explanation for Ryan's difficulty with sexual arousal when he is nervous.

2. Why would testosterone injections lower Ryan's sperm count, rather than raising it as he hopes?