Butterflies in the stomach, sweaty palms, shaking and a racing heart are all signs of being head-over heals in love. As much as hopeless romantics would chalk it up to good pick-up lines and mere charm, psychologists say that only 7 percent of what you say affects if a person falls for you. There seems to be a more scientific aspect at play in passionate relationships.

A study done by Rutgers University when researching the chemicals behind love had a subject hooked up to a MRI machine. The subject was shown pictures of their significant other.What the results showed was that when the subject saw their significant other, blood flow increased to parts of the brain that received dopamine and norepinephrine. These chemicals heighten activity, sleeplessness and addiction.
When falling in love, most people describe feelings of utter happiness and a more positive outlook.These feelings can be traced back to the releasing of dopamine, which is commonly known as the “happy chemical.”

Norepinephrine is a chemical similar to adrenaline. It produces the racing heart and a shaking effect on a lovestruck individual.

Listen to any cheesy love song and chances are the line "I can't get you out of my head" or something similar will replay. These boy bands are actually onto something; serotonin is a chemical in the brain that's released in addicts when their addiction is present, and according to Dr. Helen Fisher (anthropologist) when people start falling for one another.

Her study of love didn't overlook the sexual aspect of a passionate relationship either. Fisher showed that testosterone and estrogen are as much of a contributing factor in couples in love than any other neurochemicals.

Although testosterone and estrogen played an important role, what happens to the brain after sex is what scientists note as the “love chemical.”

Oxytocin is a chemical that has been proven to evoke feelings of contentment, reductions in anxiety and feelings of safety. The chemical is released when a mother gives birth and first sees her baby, as well as by couples after orgasm. Nicknamed the "cuddle chemical" oxytocin is what causes those feelings of attachment.

Eliezer Melamed, a well known anthropologist, wrote in his 1992 book that women find protectiveness as an attractive trait by evolutionary standards. The chemical that causes men to be protective is called vasopressin. When tested on the prairie voles, those who were injected with a chemical to stop the production of vasopressin (thus making them less protective) had their bond between their partner deteriorate and even lost their partner to new suitors.

Another study done by Pavia University proved that a protein called the nerve growth factor (used to grow, maintain, and sharpen neurons) was more than doubled in people who were in long term relationships compared to those who were single.

Whether it's creating feelings of attraction, contentment or safety, it seems that the emotions associated with love have a much more scientific explanation than being struck by Cupid's arrow.