“Absorption” is a process that involves the transport of digested nutrients directly from the cavity of the gastrointestinal tract to the lymph, blood and intercellular space. In physiology, this determines the ability of tissues to absorb the molecules they need for life, which, as a result, mutate. In this article we will provide a definition of the term, a description of the whole process and its features.
Oral cavity
Absorption is a process that takes place throughout the digestive tract. Moreover, each department has its own individual characteristics. We will analyze them depending on in which department this process takes place.
For example, in the oral cavity, the absorption of substances occurs in small quantities for the reason that the food does not stay for a long time. Only some substances are able to be almost completely absorbed in the oral cavity, quickly entering the blood cavity, bypassing the liver and intestines. For example, these are some medications (validol, essential oils, nitroglycerin), as well as a deadly poison - potassium cyanide.
As a rule, the ability of these substances to be intensively absorbed is a way of their emergency introduction into the body.
Stomach
In the stomach, under the influence of enzymes and hydrochloric acid, the process of digestion is enhanced.
It should be noted that certain types of nutrients should be processed longer than others. So, protein and fats are digested much longer, especially compared to carbohydrates. This is due to the fact that they secrete enzymes much later.
The stomach is, in fact, the focus of digestive activity, but at the same time an extremely small amount of nutrients is absorbed in it. Only alcohol, large volumes of dissolved minerals and water, a certain amount of glucose and amino acids can be absorbed in the stomach.
Small intestine
During absorption in the small intestine, absorption of almost all available nutrients begins. This is mainly due to its structure, since it is this organ that is most adapted to the suction function. During the absorption of nutrients, the course of the process is directly dependent on the surface area on which it is carried out.
One square centimeter of the small intestine contains from two to three thousand villi. In addition, each villus has microvilli - a kind of finger-like outgrowths. They increase the suction surface. Between the villi themselves are enzymes that also participate in the parietal process of digestion.
In this organ, absorption is a type of nutrient breakdown that is considered extremely effective for the body. This is explained by the fact that in the intestine there are many microorganisms. Provided that cleavage would occur only in the lumen of the intestine, microorganisms would use most of the cleavage products. In this case, very little would directly enter the bloodstream. Due to their size, microorganisms are not able to be between the villi.
Colon
Then the food enters the colon. This is followed by further absorption in the intestines. At this stage, the body assimilates water, short chain fatty acids and minerals, for example, sodium, calcium, potassium, chloride. Also here is where the absorption of vitamins produced by symbiotic bacteria takes place. These are vitamin K and B vitamins.
Polyols and soluble dietary fiber are processed by bacteria, and what is formed as a result of their breakdown is sent to the colon.
The mechanisms
The absorption of nutrients and other substances important for our body occurs under the influence of certain processes. Different mechanisms are responsible for the absorption of various substances.
Filtration laws are responsible for smooth muscle contraction, which increases pressure. This is the trigger for the absorption of certain substances into the blood. Diffusion ensures that some of the organic molecules, salts, and a certain amount of water get into the bloodstream. It is worth noting that diffusion involves the arbitrary movement of substances in solution, which leads to equilibrium from concentration in volume.
Another important mechanism is osmosis. So-called movement of molecules of different substances through a semi-permeable membrane, passing them exclusively in one direction. With an increase in osmotic pressure, the process of water absorption is significantly accelerated.
Finally, when absorbed, a large amount of energy is consumed, especially when certain substances are absorbed. These include a number of amino acids, glucose, sodium ions, fatty acids. According to the results of experiments, it was found that using special poisons it is possible to completely stop or lead to impaired absorption in the mucosa. For example, you can completely stop the body from receiving sodium ions, which can lead to a significant deterioration in human well-being.
Features
This process requires a significant increase in the so-called cellular respiration in the mucosa located in the small intestine.
Assimilation also contributes to the reduction of villi. Each of them is covered on the outside by the epithelium, and inside are the lymphatic and blood vessels, as well as the nerves. The smooth muscles located inside, during contraction, push the contents of the lymph vessel and capillary into larger arteries. In the intervals between muscle relaxation, the small vessels of the villi consume the necessary substances from the small intestine. The result is that each villus is a semblance of a powerful pump.
Within one day, about ten liters of liquid are absorbed. Of these, 4/5 are digestive juices. In the human body, the intestinal epithelial cells are primarily responsible for the consumption of beneficial substances.
Suction regulation
An important function of the digestive system is the regulators located in it. It can be nervous or hormonal regulation.
With nervous regulation, the functions of the digestive system are controlled by two types of neurotransmitters. In this case, the spinal cord or brain has an external effect on the digestive tract. As a result, certain substances are synthesized - adrenaline and acetylcholine.
Adrenaline is responsible for muscle relaxation in individual organs, and also reduces blood flow to them. At the same time, acetylcholine stimulates the muscles in the digestive system to intensively promote food along the gastrointestinal tract. In addition, this substance induces the pancreas and stomach to produce more digestive juices.
Of great importance is also the work of the internal nerves, which form a dense network in the walls of the stomach, esophagus and intestines. When, under the influence of food, the walls of organs stretch, they become more active. Internal nerves produce a large amount of substances that accelerate or slow down the production of juices and the movement of food.
During hormonal regulation, hormones that directly control the functioning of the organs of the stomach are released by mucous cells located in the small intestine and the stomach itself. It turns out secretin, which stimulates the pancreas in the production of digestive juice. Gastrin induces the stomach to produce hydrochloric acid, which is involved in the digestion of certain foods. It is also required for normal growth of the intestines and gastric mucosa.
Finally, cholecystokinin appears, contributing to the growth of the pancreas and the development of pancreatic juice enzymes. This helps release the contents of the gallbladder.
External factors
It is worth noting that a certain number of external factors affect the process of assimilation of nutrients. For example, stress refers to them. In many patients, digestive problems occur just against this background. The reaction of the nervous system to stress does not contribute to digestion, it has a negative effect on absorption.
Some take antacids to reduce the severity of symptoms, but these drugs reduce the absorption of certain nutrients. So some experts consider their use to be counterproductive.
In such a situation, the most effective method is considered to be a change in attitude to environmental circumstances, which a person is not able to influence. Often this helps to significantly alleviate heartburn and dyspepsia, restore the normal functioning of all digestive organs.
Medicines when interacting with nutrients can act in both directions. So, corticosteroids reduce the absorption of vitamin D and calcium. Therefore, they are often prescribed after sports injuries in order to reduce the inflammatory process. Other drugs may produce the opposite effect. Therefore, it is so important to carefully study the instructions, be sure to consult a doctor, intending to drink this or that medicine.
Effect of alcohol
Due to alcohol in the human body there is a lack of nutrients even when their amount corresponds to the daily intake. The fact is that alcohol damages the mucous membrane when absorption occurs in the stomach and small intestine. As a result, the absorption of minerals and vitamins changes and decreases significantly.
In addition, alcoholic beverages interfere with the breakdown of nutrients by reducing the secretion of digestive enzymes. To avoid this, it is recommended to minimize the amount of alcohol consumed.
Methods for improving absorption
It is believed that the human body is able to absorb from 10 to 90 percent of the nutrients contained in food. To normalize and maximize this value, it is recommended to take care of the restoration of the digestive tract in case of any damage or disturbance.
Instead of raw vegetables and fruits, drink more juices that are already processed, which helps facilitate the digestion process. An important role is played by the correct combination of food, thorough chewing.
Nutrient concentration
It is worth knowing that some nutrients are ways to occupy a leading position in assimilation. For example, calcium stops the absorption of iron.
You also need to remember this, monitor in which combination you consume nutrients.