The anus, saliva, stomach, oesophagus, small intestine, appendix and large intestine

Humans have two anal sphincters: an inner and an outer one. The outer sphincter is under our conscious control. The internal one is under the control of our unconscious mind: it makes sure everything is OK inside us. Between them are many sensor cells: they analyse the "tasters" allowed through by the inner sphincter and decide if they are solid or gaseous, analysing its composition and sending the information to the brain.

Suppressing our needs too long and too often cows the inner sphincter muscles causing constipation.

Childbirth can also sometimes cause tearing of the delicate nerve fibres ruining the connection between the two sphincters.

A muscle encircles the end of the large intestine when we are in a sitting position, creating a kink in the tube and making it harder for the gut's contents to be emptied. A crouching position eliminates this problem.

Saliva, is basically, filtered blood. Salivary glands sieve the blood, keeping back the red blood cells and hormones, calcium, some parts of our immune system are let through. Salivary glands also add calcium-containing compounds and natural painkillers to saliva.

-Opiorphine (stronger than morphine) is produced in small amounts in our saliva. This is because we have so many nerve endings in our mouths that even small sores would be very painful to us. Which is why sore throats feel better after eating: more saliva is produced. Can this perhaps also explain comfort eating when stressed?

-Bactericidal substances kill off some of the bacteria entering our mouths, but not all of it. Good bacteria helps even just by being there, and taking up space that could otherwise be used by bad bacteria.

-At night we produce less saliva, which is why we also wake up with bad breath, bacteria can multiply during that time.

The root of the tongue and our tonsils are made of immune tissue, that investigate any foreign substance they encounter and train the immune system to defend us.

Tonsils we can have removed because unlike the root of our tongue that has outer projections, they have inner crypts. Inside these crypts, too much foreign material can accumulate and lead to infection, tonsil stones and bad breath.

Tonsils should not be removed before the age of 7: when our immune system has "seen it all". They are very important in training our immune cells.

Why is the stomach crescent shaped?

The right-hand-side of the stomach is much shorter than the left side, so it curls up. In this way, liquid can flow against the shorter side, straight into the small intestine. Food will plop against the larger side of the stomach. So, it has two sides with different specialisations: one for fluids (short) and one for solids (long).

The oesophagus is also connected terminolaterally: to the side of the stomach. In this way, when we walk, talk, laugh, all of which cause us to clench our abdomen and put pressure on our stomach, the oesophagus has to deal with only a fraction of that pressure. Thesis why we can walk after a heavy meal without having to burp with every step.

We also have a small pouch of air on the top of our stomach, which we can see in X-rays. If we want to burp, it is easier to just swallow some air, making that gas bubble larger, and therefore closer to the opening of the oesophagus. Also, lying on your left side allows the gas bubble to escape.

The oesophagus is made out of spiralling muscle, like a phone chord. When you've eaten too much and have heartburn (the oesophagus isn't closed properly), stretching the oesophagus closes it better at either end. So sitting or standing up straight with your head looking upwards helps relieve heartburn.

Small intestine - surface area: folds - villli - microvilli - glycozcalyxes: sugar-based structures on the surface of microvilli.

The duodenal papilla (duodenal, duodenum - the first part of the small intestine and papilla, like the salivary papillae in our mouth - spurts juices) liver and pancreatic juices are delivered to the chyme through the duodenal papillae. They contain digestive enzymes and fat solvents.

Every individual villus has a blood vessel which absorbs molecules. All the small intestines blood vessels come together and go to the liver, for toxic screening.

- If we eat too much, this is where the first energy stores are created, you cannot have the extra sugar in your blood.

- Then the blood all goes to your heart, and the nutrients are pumped all through the body.

If you apply pressure to an inflamed appendix it hurts. If you apply pressure to the opposite side, it relives the pain. This is because you are pushing the fluid in the gut toward the inflamed appendix, cushioning it, which causes relief.

The appendix is part of the tonsillar immune tissue. It monitors the foreign microbes in the gut, leaving only the good germs alive - so a healthy appendix is a storehouse of the best, helpful bacteria.

For example, after a heavy bout of diarrhoea, many of the typical gut bacteria have been flushed out, leaving space for new, potentially harming bacteria to settle. This is when the appendix spreads out its good bacterial reserves.

The large intestine takes its time with all the things that the small intestine couldn't digest for around 16hours. It's bacteria also provide us with nutrients from these leftovers.

- Calcium can only be properly absorbed here.

- Vitamin K, Vitamin B12, thiamine, Vitamin B2.

- In the final metre of the large intestine, water levels are finely tuned, and therefore salt levels too.

All the blood from the large intestine also first goes to the liver for detoxification, except for the last few centimetres, which is because usually nothing important is absorbed from there - this is how medical suppositories work so fast, they can go straight to the heart and the rest of the body.

Fat digestion and transportation, allergies, lactose intolerance, fructose intolerance

Fats are not transported in our blood, they are transported in our lymphatic system, which accompanies every single blood vessel and even every capillary. Lymphatic system vessels are transparent and have no muscles of their own, lymph transportation is usually done via gravity.

It is the muscles in our legs that squeeze lymph back up with every step, so no accumulation will occur.

Fat passes into its main duct from the small intestine, and goes straight to the heart. Fat detoxification happens as the fat droplets slowly happen to pass through the liver from the body - but as the liver contains a lot of blood at any given time, the fat droplets will end up there sooner or later. But, before that happens, all the undetoxified blood is in our body.

Cold-pressed virgin olive oil is good against:

- Arteriosclerosis, cellular stress, Alzheimer's disease, eye diseases, inflammatory diseases, cancer

- It also blocks an enzyme in fatty tissue, that creates fat out of spare carbohydrates

- Olive oil is damaged by heat, so it is not suggested to be used in cooking.

- It also tends to capture free radicals fro the air. The free radicals can latch onto anything, causing inflammation of blood vessels, skin ageing, nerve disease. So olive oil should be kept in a well-closed container in the fridge.

- It also contains oleocanthal, a fat that works in a similar way to aspirin but in smaller doses. So regular use of olive oil can help those who suffer from inflammatory disease, regular headaches or menstrual pain.

What is an allergy?

If we fail to break down a protein, then it will not make it into our bloodstream. But, it may find itself in our lymphatic system, embedded in fat droplets. The immune cells can detect it there, and attack the piece of peanut for example, as a foreign body. The next time they see the peanut, they re more ready and can attack it more aggressively.

- This is why most allergies come from foods that are both fatty, and rich in protein such as milk, eggs, peanuts.

- We aren't allergy to greasy bacon: we are made up of meat ourselves and have few problems digesting it.

If the gut is too porous, substances can get to where they shouldn't be, and cause an immune reaction. Stress or a heavy bout of alcohol drinking can cause the gut to become porous, after which it is good to avoid gluten for some days.

Lactose Intolerance

It is more of a deficiency. Lactose needs to be broken down into ints constituent sugars for it to be absorbed into the body. The enzyme for this doesn't come from the paella, it should be made by the cells of the villi themselves, which must in turn digest the lactose when they come into contact with it. Sometimes they can't produce this enzyme, so lactose doesn't get broken down or absorbed.

This lactose travels on, into the large intestine. There, it becomes food for the many bacteria, resulting in fatulence and many other symptoms, due to overfed large intestinal microbes.

Fructose Intolerance

Occurs in people that have fewer fructose-processing enzymes. Fructose may therefore accumulate int heir cells, interfering with other processes. It also can appear later in life when the gut has a reduced ability to absorb fruit sugars so the majority of their fructose ends up in the large intestine.

Fructose intolerance can affect your mood.

- Sugar helps the body absorb many other nutrients too. The amino acid tryptophan latches onto fructose during digestion. So if we have too much fructose, most of it will not be absorbed, so we will lose a lot of tryptophan with it too. But tryptophan is needed to produce serotonin. So too much fructose can lead to symptoms of depression.

- Furthermore, fructose is not absorbed by all our body cells like glucose, it is only processed in the liver, where it is converted into triglycerides. Also, unlike fructose, it doesn't stimulate the release of leptin, which signals station, so we end up eating more.

How much fructose is too much?

You should consume less than 50g of fructose a day, which translates to about 5 pears or 8 bananas or six apples. More than that can lead to an upset gut, fatulence and depressive disorders.

Cigarette smoking stimulates areas of the brain which are stimulated by eating. But it therefore causes gastric acid production for no reason, and causes the sphincter between the oesophagus and stomach to relax, causing heartburn. Stopping smoking relieves heartburn.

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