We all enjoy an orgasm if we can achieve it, even if we might sometimes regret it later.
When you orgasm, there is a rush of pleasant sensations from arousal, to the "pow" of the actual orgasm and through to the "afterglow". This is caused by certain hormones which affect ones physiology, including the physiology of the brain. Here is some information on the hormones produced in the process of this crescendo of the orgasm and what there role is.
There is the obvious hormones such as adrenaline. That is the hormone that gets your heart pounding and racing, and gives you the stamina to complete the often energetic enterprise.
Then there are other obvious hormones such as serotonin and dopamine. These are the feel good hormones that you get in varying degrees when you feel good. Depressives or depressed people need a boost in these hormones.
Then there are less obvious hormones such as prolactin, which is produced in breast feeding mothers to stimulate milk production. It also has a pleasant sedating feeling that increases bonding behaviour. It is largely responsible for falling asleep in the "after-glow". And the want to snuggle and bond. It is produced by both men and women during orgasm. There must be some kind of inhibitor hormone produced or lower doses so orgasming people or the highly sexually active don't immediately start lactating!
Another interesting hormone produced is oxytonin, which produces the rhythmic pulsing during ejaculation or the squeezes during female orgasm. Oxytonin is used primarily to cause contractions during child birth.
And that's all folks! That is what is going on chemically when you have an orgasm.
The next interesting sex topic is the role of pheromones in choosing a mate.
When one becomes an adolescent, certain sweat glands in the armpits, groin region and behind the ears start producing an oilier fluid which is ones personal scent. It is a very subtle smell that often cannot be consciously detected so the information is picked up mostly by the subconscious. Its purpose is to communicate that the person is sexually mature and ready to mate. If a female is pregnant, breast feeding on hormone treatments or menstruating her scent will change. It also communicates the state of their health, in particular the immune systems strength and "knowledge". It is the pheromone scent that plays a large part in choosing a mate. As adults most of us produce the "I'm available" side of the pheromone, however not everyone is attracted to everyone (well, some of us aren't). What we find attractive in one another's pheromone information is actually the immune information. What the primal part of our brain which deciphers the smell (brain stem region at the back of your head) is looking for is a mate whose immune information is as different from ones own as possible. This is so the potential resulting offspring will have genetic access to a much broader amount of immune ability and therefore a better chance at fighting the ever changing diseases they might encounter in the world. Disease has been a big killer of the human animals during our evolution, particularly the pre-breeding young. The primal part of your mind which does this does not care if your personalities, lifestyles, or star signs are compatible (unless it becomes life threatening, and then its life preserving instinct takes over). It only cares that the offspring will have a stronger immune system then its parents. If one has a choice between two mates with different immune systems, the limbic system (mammal part of the brain) will often choose the most socially beneficial of the two for survival reasons for the child. If this works out to be genuine personal compatibility the resulting family (given the father nests or otherwise provides support) they will be content enough to become a long standing tribe. If not the instinct is to provide for the child until it is independant enough to walk, then one of the parents might leave. Leaving the offspring with better established relatives or abandonment at birth or conception is a "cuckoo bird" system. Another period of time an unhappy but provisional arrangement might part company is when the offspring begins to smell sexually mature themselves. This can be a time where not only a poorly bonded relationship may wish to part (except for security in age), but is exacabated by the offspring now smelling sexually mature and the resulting in the instinctive politics. Both child and adults(s) know it is nest leaving, mate finding time. This is also true when the adult offspring actually do leave the nest. The animal roles of the people have reached a time of change.
It might be good to mentioned here that another reason for being attracted to people whose immune system pheromone smell is very different from their own. One of the effects is it makes inbreeding far less likely to happen. A test was conducted where several family groups were asked to wear unmarked t-shirts for a couple of days. Then the test group was asked to smell the t-shirts without knowing who had worn them. People consistantly found the smell of sexually mature blood relatives the least attractive. What smells bad to your relatives might well smell good to a potential mate. Another thing to mention is if a person does genuinely have a unpleasant body odour (B.O.), it is caused by certain bacteria feeding on the oily pheromone secretions and is NOT the persons personal smell. Help for this curable condition can be found at the chemist or pharmacy.
Another human "cuckoo bird" pattern, by the why, is for a mate to choose a mate who is well established in resources, and may have offspring with them as a pay off, but females may stray with a better smelling mate especially, it has been found, near ovulation (subconsciously on all parts), and for males, younger fitter (breeding age) females.
Another interesting sex fact is that the frontal lobes of the brain (the bit that does higher thinking such as mathematics, problem solving, art) actually shuts down when people are in a sexually aroused state. The primal part of the brain ( the reptilian part at the brain stem) and the limbic part (with mammalian behaviours and more complex emotions) light up like a Christmas tree in an EEG test, while the lights refuse to shine for the frontal lobes. Peoples ability to think logically or with higher more abstract concepts greatly diminishes. There is an obvious evolutionary explanation for this. Humanity for millenia has been trying to outwit nature in the process of having the enjoyable thrills of sex without the production of young, the reason nature made such an odd activity enjoyable. Obviously people have outwitted nature in the past to the point that no offspring were produced. However, certain sections DID produce young, and they were the people whose frontal lobes were impaired when they were aroused, making mistakes and not sticking to the plan. Thus we are stupefied when in a state of lust. Natural evolution can be intellectually fascinating!
Does anyone know what prevents prolactin produced during orgasm causing lactation in men and woman?
Or what chemical changes occur to shut down the frontal lobe activity during sexual arousal?
A good reference book on the topics is "The Science of Orgasm". Not sure of the publisher or authors (2).