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why do we get butterflies in our stomachs

If you have ever been nervous about something that is about to happen, then you may have felt the sensations of nausea and fluttering the recognisable and odd sensation deep in your gut known as having butterflies in the stomach. Perhaps you were about to give a speech to a large audience, were in the waiting room for a big interview, were about to step up and take a key penalty shot or about to meet a potential love interest. Rather than actual butterflies bouncing around your large intestine, of course, there is of course something more scientific going on and its all down to your nervous system. The human body is capable of looking after itself without too much voluntary thought. It quite happily regulates heart rate, blood flow and the distribution of nutrients around the body without you having to consciously intervene in any way a process run by the
(ANS). The ANS can be split into two roughly equal branches the sympathetic and the parasympathetic, or, as it is memorised by every first year medical student, the branches.

Both branches of the ANS are constantly active, and act in opposition to each other. The nervous system is what makes you feel tired after dinner. The sympathetic (fight-or-flight) system is responsible for increasing your heart rate, while the parasympathetic (rest-and-digest) system decreases it. So, the rate at which your heart is beating is the balance of the activity of the two branches of the ANS. The dominance of the parasympathetic branch is why you feel content and sleepy after a giant lunch. Quite of bit of blood flow from the heart is directed to the stomach, and your ANS encourages you to sit down for a bit to let digestion take place. So whats this got to do with butterflies? One of the major roles of the ANS is to prepare you for what it thinks is about to happen. This gives an evolutionary advantage, since if you see a sabre-toothed tiger about to pounce, you dont want your valuable oxygen-filled blood to be busy with your last meal.

Ideally you would want this blood to be temporarily redirected to muscles in your legs so that you can run away slightly faster. So, your fight-or-flight sympathetic system kicks in and becomes dominant over parasympathetic activity. This also causes a, which both increases your heart rate (to pump more blood and faster), releases huge amounts of glucose from the liver, and shunts blood away from the gut. The blood is redirected towards the muscles in the arms and legs which makes them ready to either defend you, or run away faster the fight-or-flight that youll probably be familiar with. However, this acute shortage of blood to the gut does have side effects slowed digestion. The muscles surrounding the stomach and intestine slow down their mixing of their partially digested contents. The blood vessels specifically in this region constrict, reducing blood flow through the gut. While adrenaline contracts most of the gut wall to slow digestion, it relaxes a specific gut muscle called the , which is why some people report a pressing need to visit a bathroom when theyre nervous.

This reduction in blood flow through the gut in turn produces the oddly characteristic butterflies feeling in the pit of your stomach. It senses this shortage of blood, and oxygen, so the stomachs own sensory nerves are letting us know its not happy with the situation. So why do we call it butterflies? It certainly does feel like and get described as fluttering by a lot of people, and I guess jaguars in your just doesnt sound as plausible. They advertised for volunteers who were in love. After sifting through the responses, three quarters of which came from women, they chose 11 women and six men in their mid twenties. All had fallen in love within the past six months to a year. During the scans, the students were shown pictures of loved ones or a friend of the same sex and age as the object of their affections.

Seeing a lover prompted activity in four distinct brain regions that were not active when looking at pictures of the friend, New Scientist reported last week. Two of the areas were deep in the cortex. One was a spot in the medial insula, the mysterious central lobe of the brain whose function is still a puzzle. One of its roles appears to be in perception of the gut, raising the possibility that it is responsible for butterflies in the stomach. It has also been linked to the perception of pain. "This could be something to do with butterflies", said Mr Bartels, who has just completed a Phd. Another distinct spot was in the anterior cingulate, part of the brain that is active when people are asked to reflect on their own feelings and emotions. Mr Bartels is confident that he was measuring brain activity associated with love - and not simply sexual attraction. "But of course, sexual attraction is part of it," he added.

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