The brain governs the entire sexual experience. Think of it this way: Your brain holds the key for turning on the sexual engine. The sexual arousal process can't even begin unless you have the right key. There are many specific qualifications in order for this key to work. One, the key must have the right design - the situation must be sexual for you, and what this means varies greatly by individual. Two, it must be able to fit the keyhole - you must be receptive to allowing sexual stimuli and thoughts to enter into your head and not be distracted by insecurities, stress, fears, and so on. Three, the engine must turn over and start when you turn the key - your neurotransmitters, hormones, and cardiovascular system must all work properly to get the sexual processes going. Four, you must have a rewarding driving experience in order to use the key again - the sexual experience must be pleasurable and desirable.
When these prerequisites are met, the brain starts sending messages via neurotransmitters to the rest of your body, telling it to go into "excitatory" rather than "inhibitory" mode. Neurotransmitters in the brain, such as dopamine, stimulate the sexual response, whereas others, such as serotonin, inhibit it. This helps explain why certain emotions (e.g., depression, which is frequently associated with low dopamine levels) and medications that affect neurotransmitter levels can influence sexual functioning. A message is sent down the spinal cord, through the nerves, to the various organs involved, including the heart and the genitals. The natural sexual reflexes then unfold.
Similarly neurotransmitters go to work in the genital region. Those released by the parasympathetic nervous system (PNS), such as nitric oxide, promote swelling of the erectile tissue in the vagina and penis. Neurotransmitters from the sympathetic nervous system (SNS) are involved in ejaculation. Sexual medicines make use of these peripheral neurotransmitters. For example, Viagra works indirectly by increasing the level of nitric oxide in the penis to enhance erections. Performing certain activities, such as exercising and eating specific foods, can boost levels of neurotransmitters involved in sex, whereas other activities, such as smoking, can negatively impact neurotransmitter levels.
In addition to neurotransmitters, hormones also play a crucial role in determining sexual functioning. Testosterone, which is known as the male sex hormone because men have about ten times more of it than do women, drives sexual interest and the biological response to arousal in both men and women. Increased levels of testosterone lead to more fantasizing, sexual desire, and sexual activity. Estrogen, the female sex hormone, helps make sex comfortable for women - it is important to vaginal lubrication. Abnormally low levels of these two hormones can lead to loss of libido and reduced sexual pleasure. Low levels can also lead to suboptimal ovulation in women and low sperm production in men, resulting in fertility problems. Many of the activities that you do every day, including exercising, sleeping, and reacting to stressful events, impact your body's production of these key hormones.
Your sexual capacity also depends on your cardiovascular health. In order to achieve optimum erections in men and arousal in women, adequate blood flow must be able to reach the arteries of the genital region. Your genitals act like a pump, with blood flowing in through a fine, flexible hose, which are your arteries. When the hose is clogged, blood flow is slowed and therefore arousal is reduced. On the other hand, when your blood vessels are free of cholesterol and your heart is pumping healthily, you are more likely to experience optimum sexual performance. Cardiovascular health depends on consuming a balanced diet, maintaining a healthy weight, exercising, and reducing stress.
Finally, general health impacts your sexual wellness. Often, we don't think about the fact that the body is a connected, unified entity. If one part of your body isn't working - you have a cold, for instance, and your immune system is busy fighting off the virus - then other parts of your body will be affected as well. You won't be able to run as fast or get as much done during the day. At the same time, you won't have the energy or stamina for sex that you do when you're in good physical condition.