The human digestive tract is a very complex machinery whose purpose is to allow digestion and absorption of food we eat. It begins with the mouth with teeth that grind food to make them more digestible. Then the food passes into the stomach where they are subjected to acid digestion and enzymatic (as well as enzymes for detergents greedy destroy stains, our enzymes break up food into small pieces), then pass into the small intestine so called because it is not big but is 7 to 8 meters long. This part of the intestine is crucial because this is what happens the absorption of almost everything, water, minerals, proteins, sugars, fats. In this article we will only consider the absorption of water.
To indicate the quantities we will take as a reference adult body surface area = 1.73 m² and a baby 1 year (10 pounds) with a body surface of 0.5 m². flows are indeed proportional to the surface of the skin and not by weight.
Where does the water absorbed by our intestines?
The water we drink and food that contained in food represents only 2 to 3 liters for an adult and a bottle for an infant of 10 kg. Contrary to what one can imagine that our water intestine absorbs or 9 to 10 liters per day for adults and 2.5 to 3 liters for an infant comes primarily from our body . It runs in a loop especially at mealtimes. This is the enterohepatic systemic water!
Liquid (liters) Adults Children 1 year
dietary 2-3 1
Secrétions digestives
estomac 1,5 0,5
Foie 0,5 0.2
Pancreas ; 1 to 1.5 0.4 to 0.7
Small Intestine 3 , 0.5
proximal ;
Total 9 to 10 2.5 to 3
Thus we see that in the Child the flow of water is much more important , since a third of its weight in water is secreted and then reabsorbed immediately within 24 hours. It is understandable that any disturbance inputs (lack of water, vomiting) or losses (vomiting, diarrhea, heat stroke) can lead quickly to a critical situation. Therefore diarrhea in infants is rightly a high risk situation, although fortunately, things change very often.
Whither water?
The water we drink or is contained in foods (milk and its derivatives are mainly composed of water) is present in the stomach. It is modified to have a composition quite close to the plasma that makes up our blood. This is why "pure water" remains longer in the stomach. It mixes with secretions different and requires small amounts in the small intestine.
is the small intestine that is responsible for 90% absorption of the water it receives.
It is here that the absorption process instead. The structure of the small intestine is made crypts and villi, which increase the exchange surface between the bolus and the tissue. Specialized cells in the absorption of nutrients are present in enterocytes that their surface microvilli, which, as the villi tissue, their role is to increase the exchange surface. Thus, we consider that the human gut has a contact surface with the bolus equivalent to the area of two tennis courts (400 m2).
How is the reabsorption of water?
There is an extremely effective mechanism and practically always functional: The coupling between the absorption water, salt and glucose . It is the enterocyte , specializing in digestive cell absorption is responsible for this work.
Glucose ( G) is the grape sugar. It is abundant in table sugar ( G + F ructose) and in starch which is the component ( G + G + G) ... Starch is found in wheat (pasta), the rice, potatoes, etc ...
Na is sodium found in table salt (Na Cl).
Water is everywhere at the tap, milk, fruit, and all foods
The co-transport glucose-sodium-water:
Water arrives in the intestine of side of light (lumens). She is accompanied by glucose and sodium. At the microvilli of the brush border of carriers are "active" specific glucose and sodium (red) . These transporters use energy. Sodium is sent, with water in the capillaries and throughout our body through "sodium pump" located on the other side of the cell ( green) on the basolateral membrane. This reaction produces the necessary energy.
This mechanism is almost always in full force and effective . He should try to stimulate it in cases of acute diarrhea. That's why we use re-hydration solutions we give often and split to avoid exceeding the capacity the diseased intestine. These solutions were initially developed for the treatment of cholera which is a model of secretory diarrhea.
Vibrio cholera: a bacterium is flagellated which moves in contaminated waters
Photo University Bordeaux
bacillus cholera toxin stimulates the secretion mechanisms. It causes diarrhea profuse 5 to 8 liters a day and occurs in countries where the infra structure does not allow for infusions. In addition, the infusions were trying to compensate for the losses but the diarrhea remained the same. By simply drinking a mixture of water, sugar and salt, we were surprised to see that "those who drank had stool less abundant than those who did not drink" and healed faster . had been stimulated absorption mechanisms.
implications of such knowledge on the treatment of gastro-enteritis:
must therefore stimulate the mechanisms of absorption, which are mostly intact : two principles that we will develop in another chapter : rehydrate and nourish. Since we're on the water, see the side re-hydration: at will, split, often.
past, we used the form of soup, carrot containing up to 4.5% sugar. What was remarkably intelligent. The carrot soup is made with 500 g of carrots per liter of water, which resulted in a solution containing 1 gram of sugar per liter as our plasma and a little salt . In addition, the core bring fibers that chelate bile salts and reduce their power of irritation in the colon that does not like them at all. . Water lightly salted rice , share the same principle as the rice is mostly starch that is converted into glucose. Our grandmothers were very strong!
solutions Oral rehydration (ORS) swept the carrot. You could almost regret but "it is progress! What
the rest is water that is not absorbed by the small intestine?
Good question I almost forgot!
Colon is just after the small intestine in the digestive tract and measures approximately 1.5 meters long. Its role is mainly to store the waste, recover water, maintain water balance, and the absorption of some vitamins such as vitamin K. According to the composition of water varies from plus or minus 5%, the stool can be liquid or molded. But the diarrhea of colonic origin have not plenty of diarrhea small bowel.
NB
This article is just a glimpse of a small portion of bowel function vis-à-vis water. Do NOT attempt to treat your own children in case of acute diarrhea. The hydration status should be evaluated by a doctor. Even if you saw a doctor and you're calmer, get up 2 or 3 times during the night to watch the baby and offer him a drink, without forcing .
We see again the " acute diarrhea or gastroenteritis " . The simple rehydration not enough
Acknowledgements: I thank
Dr. Jehan-François Desjeux pediatrician who taught me everything about diarrhea when he worked with cholera toxin to developing solutions re-hydration. He became Director of Research at INSERM and Professor at the INAM.
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