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Vomiting, motion-sickness, constipation, laxatives, the three day rule, nerves and the gut

Pregnancy hormones relax the womb muscles, but also the sphincter of the oesophagus, causing heartburn. Some hormonal contraception also causes the same effect.

Gastritis is the inflammation of the lining of the stomach.

Reflux is especially dangerous when bile from the small intestine reaches the oesophagus through the stomach. This can confuse the oesophageal cells into thinking that they are intestinal cells, making them change into them. These cells often mutate, and no longer grow and replicate in a controlled way, causing oesophageal cancer.

A lot of saliva is produced before vomiting so it can protect our teeth from the corrosive effects of stomach acids. Animals that cannot vomit do not eat in the same way as us. They have to nibble at their food, testing its suitability. Furthermore, their livers have more toxin breaking substances.

The more solid and undigested the contents of the vomit are, the more likely they came from the stomach.

Sudden vomiting in a violent surge with almost no warming is probably a gastrointestinal virus. Sensors count how many pathogens they encounter: if they are beyond a certain threshold they cause emergency vomiting.

Food or alcohol poisoning can also cause vomiting in surges, but with more warming beforehand = nausea.

Motion Sickness

Occurs when the information the body is getting from its eyes is at odds with that from the ears: the body pulls its emergency breaks and vomits.

CFR (corticotropin releasing factor) is a hormone produced to tan our skin, prevents the immune system from overreacting but is also a stress hormone in upsetting situations. The gastrointestinal cells also secrete it in times of stress or danger. So when gastrointestinal cells register large amounts of CFR, irresponsive of its source, the brain gets intense feelings of emotion stress, strain, anxiety, our body reacts with diarrhoea, vomiting, nausea.

When the brain is stressed, the vomiting is done to save the energy digestion would need and use it for the problem at hand.

When the gut is stressed, the vomiting is done either because the food is toxic, or because the gut isn't in a position to complete the digestion.

Ginger contains substances that block the vomit centre in the brain.

Constipation is defined as having a bowel movement less than three times per week, having particularly hard stool form a quarter of the time.

It results from a disconnection between the nerves and the muscles of the gut. The nerves put the breaks on bowel movement when, for example, you're travelling. How to minimise constipation:

1. Dietary fibre, the best are plums. Or buying dietary fibre from the store, about 30g/day should be consumed.

2. Consuming sufficient fluids. Especially during flights, the dry air draws out even more water than usual from the body. So you should drink more water than normally.

3. Try to complete the bowel movements you usually would at the same times. The gut is a creature of habit. The longer you leave the faeces in the gut, the more water is extracted from them, making them even harder.

4. Probiotics and Prebiotics can breathe new life into a tired gut.

Types of laxatives

Osmotic laxatives: are sugars or salts or short molecular chains that use osmotic water regulation. They make their way to the large intestine, and there, when part of the bowel contents, they draw in water because of the added concentration, making bowel movements easier. If, however, you take too much, you end up having diarrhoea.

Lactulose is the most common laxative sugar. It acts by 1. raising the stool concentration and therefore drawing in water and 2. feeding the gut flora that can produce substances that can act as stool softeners. But too much can cause gases: cramps and fatulence. Lactulose is made by high-temperature milk.

Sorbitol: occurs naturally in some fruit: plums, pears and apples. It isn't absorbed into the bloodstream, so it is used as a sweetener which is why some cough drops have a laxative warning.

Short molecular chain laxatives are best tolerated by the body: unlike salts, they don't disrupt the body's electrolyte balance, and unlike sugars, they don't feed gut bacteria and produce gas. So they can be used over longer periods of time with little side effects.

Osmotic laxatives make faeces moister and increase their mass. The more there is, the more motivated the gut will be to move = the basic principle of the peristaltic reflex.

Faecal lubricants make defecation easier and less painful, but fat-based lubricants cause many fat-soluble vitamins to get dissolved in them and then they are simply defecated.

Hydragogues latch onto gut receptors and signal them to stop extracting fluid from the food passing through and to just let it out. Often use damages the normal activity of these nerves, so hydragogues shouldn't be used more often than once every 2-3 days.

The 3-day rule

Must be remembered when using laxatives. The gut has three parts, and usually we just empty the third and last part. But laxatives usually cause full emptying of the gut, so when no more defection happens again because the first two parts need to be filled, laxatives are used again and the problem repeats itself. You should wait three days after laxative use, its normal.


The only reason for having a brain is movement: pulling faces, talking, running, walking, influencing the world around us even by moving. But if you're a tree and you can't chose to move or not, you don't need a brain. Like the sea squirt that no longer needs its brain once it has found a place to permanently settle down.

The gut also has an unimaginable number of nerves, comparable only with the brain, and that command many signalling substances, nerve insulating materials and ways of connecting.

The regions of our brain that signals from the gut can get to: insult, limbic system, prefrontal cortex, amygdala, hippocampus, anterior cingulate; affecting self awareness, emotion, morality, fear, memory, motivation.

The vagus nerve: the most important route from gut to the brain. Runs through the diaphragm, between the lungs and the heart, up along the oesophagus, through the next to the brain.

The brain depends on sensory organs to get a picture of what is going on: it is very isolated itself by a thick skull and very well filtered blood. The gut is right in the thick of it, with such a large surface area and so many nerves, it is the largest sensory organ.


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