Hi Karl! This might not be ALL of the chemicals involved in sex (including orgasm) and love/romance, as well chemicals released in semen during ejaculation (some of which absorb into the woman's body and enter the bloodstream) but it's some of them at least. Dopamine, oxytocin, vasopressin, phenylethylamine, adrenaline, endorphins (including enkephalins), serotonin, norepinephrine, prolactin, testosterone, estrogen (comes in 3 forms), progesterone, corticosterone (not sure about this one), nitric oxide (NO), pheremones, neutrophins, luteinizing hormone, androstenedione (precursor to male and female sex hormones), Tyrosine (precursor to dopamine and norepinephrine), pheromones (some mentioned such as testosterone), follicle stimulating hormone, cortisol, prostaglandins, thyrotropin-releasing hormones, melatonin, relaxin, cytokines, placental proteins, including human chorionic gonadotrophin (hcg) and human placental lactogen are all involved. I left out some sex hormones. You can search wikipedia for a list of those (some are above, some aren't), Sex hormone binding globulin (SHBG) binds to some sex hormones, rendering them unusable. :( Not much of a fun thing is it (SHBG)?
Anyway, I wrote a big thing in response to this, but I can't post it all. It's too long. If you want more info. on these things ask and I'll post it. I tell you what, I'll post a bit, anyway, just because, otherwise, it's boring.
Some of the major ones are dopamine, serotonin, oxytocin, vasopressin, phenylethylamine, adrenaline, endorphins (including enkephalins), norepinephrine, testosterone and estrogen. I won't be as detailed as I was when I first tried to write a reply because it was SO long, but here are some little tidbits.
Dopamine is a neurotransmiter that deals with pleasurable feelings and leaves you feeling blissful. It's also associated with the reward centers of the brain. It is also associated with craving, desire, motivation, goal oriented behavior, attentive focus, and addiction. It's also involved with sexual desire, as well. So it makes you feel blissful around a person, attracted to them, and a bit addicted to them. Just seeing a photo of your new love could cause a surge in dopamine related brain activity.
Serotonin goes down during new, passionate love. People in the attraction stage of love have serotonin levels similar to people with obsessive compulsive disorder which might explain why some new lovers obsess over one another. Serotonin is released during orgasm, however, which could have an anti-depressant affect on people, leaving them happier, more optimistic, and more satisfied after sex.
Oxytocin is a bonding hormone, and so is vasopressin. Oxytocin causes people to form bonds and long term attachments. It also causes affectionate feelings for another person, increases trust, makes you see people in a more positive light, etc. On a more sexual note, it helps with contractions which are involved in orgasm, helps stimulate the prostate, and helps increase never sensitivity, so it might be responsible for more, easier, or/and better orgasms. Oxytocin is also released during orgasm, possibly causing lovers to bond more. Women have higher baseline levels of oxytocin, have more oxytocin receptors in their brains, I believe they release more during sex, and to they have higher estrogen levels- that is relevant because oxytocin needs estrogen to work, so it might work better with more estrogen. Eye gazing, cuddling, touching in general, sex and orgasm all make oxytocin go up. In men, kissing also elevates it. Vasopressin and oxytocin are in both genders, but it is believed that oxytocin might have greater affects in women and vasopressin in men. Men also release vasopressin during orgasm. Vasopressin is related to monogamy, pair bonding, and attachment in non-human animals and is believed to have a similar function in humans.
Phenylethylamine has an anti-depressant affect and helps in the release of norepinephrine and dopamine, other love related hormones. It can increase heart rate and blood flow, and as a result of the latter, possibly sexual arousal and pleasure. Eye contact can increase it, causing pupil dilation, when you see something that appeals to you. It is sometimes a sign of attraction.
Adrenaline makes you feel excited/exhilerated, and even nervous. It's the flight or fight response. In the early stages of fallin in love, your body's stress response kicks it up a bit, increasing blood levels of adrenaline and the stress hormone, cortisol. This might be somewhat responsible for the racing heart, and the butterflies in your stomach feeling of falling in love. Adrenaline also causes pupil dilation, increased heart and breath rate, and a decrease in hunger. Thanks to the increased heart rate and dilated arteries that come with adrenaline boosts, you get increased blood flow to your muscles, which is a plus during sex. Along with love, anger, fear, exercise (including sex) and other mental/physical stress can increase adrenaline. During sex, extra adrenaline is released from the adrenal glands. Adrenaline is one chemical responsible for the recovery period men need after sex before most of them can have another orgasm, according to an article I read on askmen.com. Another such chemical is prolactin.
Endorphins are feel good chemicals produced by the pituitary gland and the hypothalamus. They are natural pain killers and lower stress. They induce a general sense of well being, cause feelings of euphoria, and relaxation, etc. Some also increase confidence. Not only is it love related, it is released during orgasm. Laugher, physical contact, pain, exercise, excitement, eating spicy foods, and consuming chocolate can increase endorphin levels. They can be addictive and have a structure similar to morphine, but they're safe. Enkephalins are a type of endorphin. They bind to the body's opiod receptors. They might help out with orgasms, decrease anxiety, and also be a partial contributor to after sex feelings of sleepiness. Some believe they might help immune function. They are released in male semen and might absorb through vaginal walls.
Norepinephrine- Like adrenaline, this produces excitement and racing heart. It can make you feel infatuated and I think, focused on someone. High levels of dopamine are also associated with norepinephrine.
Testosterone- Male sex hormone, found in both genders, but to a much larger degree in males, though I believe women are more sensitive to lower levels of it. It has multiple purposes, but to name a couple, it is a big factor in both male and female sexual desire, and helps with clitoral engorgement and penile erections.
Estrogen- A female sex hormone found in both genders, but to a much larger degree in women of reproductive age. It helps the fertility cycle, helps with female lubrication (important for general and sexual comfort, as well as increases the pleasure of sex among other things), thickening of vaginal walls (also good for sexual pleasure), etc. And as I said earlier, it's needed for oxytocin to work as a bonding agent. :)
Various. Several came from the following article, though, since many of the chemicals in the semen, I would have been unaware of otherwise. As far as general sex, orgasm, and love hormones, I had too many sources to name, and it seemed general data/knowledge/domain as far as what is posted above.
And here's the askmen article I mentioned above:http://www.askmen.com/dating/love_tip_25...