There are four stages in an orgasm: excitement, plateau, orgasm and resolution.
Following arousal, the brain sends messages which increases blood flow to your genitals, and your heart rate increases.
Men and women experience orgasms differently...
For men, the orgasm tends to last between three and 10 seconds, followed by a "refractory period" anything from a minutes to hours - which is why men can't achieve another orgasm immediately after they've experienced one.
Women on the other hand, tend to experience longer bouts of pleasure - around 20 seconds - and they have no refractory period, which gives the opportunity for multiple orgasms.
Men and women also feel pleasure in different areas: for men, the anal sphincter, the prostate gland and the penis muscles all contract.
Women on the other hand, have "rhythmic contractions" of the uterus, vagina, anus and pelvic muscles.
The brain becomes less active, and certain areas shut down altogether.
Thirty regions of the brain remain active, and are, at first, flooded with dopamine which makes you crave the feeling of orgasm again, followed by Oxytocin which increases feelings of love and bonding between you and your sexual partner.
The lateral orbital frontal cortex however shuts down, which controls self-evaluation, control and reason.
Women also tend to feel calmer and as though in a "trance", and men are less aggressive.
What’s interesting is that an area called the periaqueductal gray (PAG), which controls the 'fight or flight' response in humans is activated during orgasm. The cortex, which is associated with pain also has activity, implying a relationship with pleasure and pain.
There you have it: in case you wanted to overthink sex even more.
You can watch the entire video, made by ASAPscience, below: