The Digestive Process
System Elements
People's problems are not because they lack knowledge, but rather that they know too much that is untrue.
Josh Billings's Encyclopedia of Wit and Wisdom
There's a cliché that goes, "You are what you eat," yet if all you eat is veggies, you surely won't turn into a vegetable. Digestion, an intricate process that occurs inside our bodies as a result of everything we eat, is essential to maintaining life. It's critical to have a fundamental understanding of how our digestive system functions in order to comprehend the problem of obesity and how various weight-loss procedures operate.
The food we eat contains all of the components and essential energy sources that our bodies need. The process of physically and chemically transforming food all the way down to the molecular level can be summed up as digestion. Before any of the hamburger you had for lunch can be absorbed into your bloodstream, it must first be broken down into its molecular components. Only then can the body actually use the proteins, lipids, and carbohydrates we consume.
Proteins are broken down into amino acids by the digestive system, carbs are converted to simple sugars, and lipids are converted to fatty acids and other compounds like cholesterol and triglycerides. These fundamental building blocks are subsequently utilized as energy sources or as structural components for the development of new tissues, the healing of wounds, or the restoration of sections that degrade over time. Anything that is not immediately required for survival is eventually turned to fat and stored in various locations throughout the body.
gastrointestinal system
The image below illustrates the primary two components of the human digestive system. The alimentary tract, a lengthy tube that extends from the mouth to the anus, is the primary part. The other organs in the system provide different substances to the alimentary tract that are necessary for digestion. These include the pancreas, liver, and salivary glands.
The system appears to be quite straightforward. After putting food in one end, waste finally comes out the other. However, one of the true mysteries of life is what occurs in between. Every body needs the same nutrients, regardless of whether the person is a world-class athlete or a newborn baby, a manual laborer or a grandmother rocking back and forth.
The alimentary tract, which is the tube from the mouth to the anus, and a multitude of organs that add various chemicals for digestion make up the two major components of the digestive system.
Automatic Digestion
Eating is a choice process that starts a complex chain of automatic processes. Although it may seem like this process doesn't start until you put food in your mouth, the body actually starts preparing far earlier. Your mouth produces more saliva at the mere sight, smell, or even concept of food, which also causes your stomach to churn more and produce more acid. That is where expressions like "stomach growling" and "mouth watering" originate. digestive system
Both chemically and physically, the system is prepared for what is to come.
In addition to the real nutritional content, the meals we eat come in a range of various shapes, sizes, textures, consistencies, and flavors. Despite having quite distinct physical properties, a T-bone steak and a glass of milk both contain a lot of the same proteins, lipids, and carbs. Milk is a liquid, therefore it doesn't actually need to be mechanically digested or moved around by our bodies to help with digestion. Mother's milk can be digested even by a baby. But it needs to be mechanically altered in order to digest a large piece of steak.
Usually, we break down large chunks of solid food into smaller, more manageable bits to begin the mechanical digestion process. Even while eating a lot of food without chewing is conceivable, it is very ineffective. The digestive process is vastly improved by chopping solid foods into smaller bits.
For many reasons, chewing is a crucial component in mechanical digestion. Our teeth are made to rip and ground food into ever-tinier pieces so that they can be more easily swallowed. Chewing also incorporates saliva, which is created by a number of glands in the mouth, into the food. Saliva contains some digestion enzymes called amylase and functions as a lubricant to make food easier to swallow. Even before you consume the carbohydrates, these enzymes start the chemical alterations.
We usually appear to be in a rush, and it takes time to chew many meals adequately. Your mother was right when she said, "Slow down and chew your food." In actuality, eating too quickly, taking big pieces, and inadequate chewing are all eating behaviors linked to obesity.
But chewing does not end mechanical digestion. When you swallow, food travels via a tube called the esophagus from the back of your throat down into the stomach. A liter or more of food and liquid can fit comfortably in the stomach, which is a big pouch. It generates a very concentrated
Even the most difficult meals we eat can be broken down by a solution of hydrochloric acid.
The effects of acid on mechanical digestion in the stomach are not the only ones. The stomach works like a large mixer, turning the food into a thick paste mechanically. The peristalsis, or repetitive contractions of the muscles of the stomach wall, physically grinds the meal. Food is moved along by a natural "milking" activity that takes place throughout the GI tract. The muscle valve known as the pylorus, located at the base of the stomach, keeps food from leaving the body until it has the consistency of oatmeal. When the food has been mixed with the acid and turned into mush, the pylorus remains closed and acts as a "mixer," releasing the food into the small intestine where the remaining chemical reactions of digestion take place.
Chemical Digestion, the Pancreas, and the Liver
It takes more than just chewing, swallowing, and letting the stomach grind for a time to break down complex substances—like a piece of chicken or an apple—into small, submicroscopic molecules that can be absorbed into the bloodstream. To explain all of the many chemical processes involved in fully digesting a meal would definitely go beyond the scope of this book. The important thing to remember is that huge, complicated compounds must be broken down into their smaller component components by digestive enzymes and bile.
The majority of the foods we eat can be thoroughly mixed in the stomach and easily dissolved in water, but as we all know, "oil and water don't mix." Fatty foods tend to collect as separate oily globs within the otherwise watery fluid as it passes out of the stomach. These fatty clumps need to be broken down into little pieces, or globules, in order for fatty foods to be digested. Bile is essential for the emulsification of fatty meals, a process known as emulsification. Bile, which is made by the liver, is mixed with food as it enters the duodenum, the first segment of the small intestine.
Similar to how soap seems to get rid of grease when you wash the dishes, bile aids in the breakdown of big fat globs. The natural barrier between oil and water is destroyed by it. The fatty substance is broken down into minute droplets, which are better incorporated with other food particles in the watery fluid surrounding them.
A network of tubes known as the bile ducts is responsible for transporting bile from the liver to the intestine. Bile is temporarily stored in the gallbladder, a little pouch that is situated under the liver. A hormone known as cholecystokinin is released into the bloodstream as the stomach grows full of food. When the gallbladder is stimulated to contract, bile is physically forced through the main bile duct and into the gut. In this manner, a significant amount of bile can be added to the food just when it is most necessary.
Gallstones are unfortunately a common cause of issues with the gallbladder. These are merely crystallized bile, and when they develop, the gallbladder must frequently be surgically removed. Since the gallbladder serves only as a storage space, removing it does not stop bile from being added to food, but the system is less effective than usual. Generally speaking, unless you consume a substantial, fatty lunch, it is not a problem. Some of the fat may pass through the colon partially digested if there is no gallbladder to contribute huge volumes of bile all at once. These undigested fats irritate the lower intestines, resulting in diarrhea or cramping in the abdomen. For this reason, it's common advice for those who had their gallbladder removed to stay away from really fatty foods.
Although the mechanical processes of chewing, the stomach's acidic mixture of food and drink, and the bile's action on fats are all significant, the actual digestive process takes place at the molecular level. Digestional enzymes are a class of highly specialized molecules required for the chemical reactions that break down our meals. These enzymes enable the food we eat to enter our mouths and eventually travel through our bloodstream for distribution throughout the body. Enzymes can be divided into three main categories for the sake of simplicity. Each group is
called after the type of material that it helps to digest. The enzyme known as amylase breaks down starches and other carbs into simple sugars. Lipids, or fatty compounds, are broken down by the enzyme lipase into fatty acids, cholesterol, and other absorbable fats. Protease degrades complex protein molecules into their building blocks, known as amino acids.
The salivary enzymes were mentioned before in the mechanical segment, but they are also part of the chemical digestion process. Saliva contains the enzyme amylase, which begins the process of chemically breaking down carbs. When compared to the amount produced by the pancreas, the amount of amylase in saliva is quite low. The majority of amylase and practically all of the lipase involved with digestion are produced by the pancreas and are added, along with bile from the liver, directly to the meal as it passes out of the stomach. We simply would not be able to digest even the most basic foods without the help of pancreatic enzymes.
Chemical digestion doesn't truly start until the meal enters the first section of the small intestine, known as the duodenum, because bile from the liver and pancreatic enzymes are not added to the food until this location in the alimentary canal. As it relates to obesity surgery, the particular spot where pancreatic enzymes and bile are added to the food we eat is crucial since a person's anatomy can be surgically altered, substantially impacting the entire digestive process. In other words, a surgeon can truly alter a person's capacity to absorb and digest particular meals by changing the digestive tract.
Unlike amylase and lipase, protease enzymes are for the most part produced by the cells that line the lining of the small intestine. The protein in a steak can be swiftly converted into amino acid molecules that are tiny enough to enter the bloodstream.
Absorption and Conversion
The last stage of digestion entails extracting those little molecules of simple sugars, fatty acids, amino acids, and vitamins out of the meal after it has been physically and chemically broken down into its constituent parts.
and nutrients from the intestine into the blood. The small intestine is where it all happens. Its diameter ranges from an inch to an inch and a half, and its length is roughly 18 feet. The real surface area of the intestine, where nutrition absorption takes place, is much bigger than it appears to be. The reason for this is that the interior of the intestine is covered in millions of small fingerlike projections known as villae.
Each villus has a minuscule network of capillaries that can take up molecular nutrients and deliver them right into the bloodstream. Larger fatty molecules are taken up through a tiny one-way channel called a lacteal, which finally links with the bloodstream via the lymphatic system, after being absorbed into the villus. Due in large part to the presence of millions of villae, which significantly increase the total available surface area in which nutrients can be absorbed, this mode of absorption is particularly effective at absorbing almost all nutrients that are available.
Before entering the major circulatory system, some chemicals that are absorbed into the bloodstream, including ammonia, need to undergo chemical transformation. If not, they will have harmful toxic effects, especially on the brain. All of the blood from the intestinal system first travels via the liver for detoxification to avoid this predicament. The liver also carries out a number of chemical processes that convert ingested nutrients into substances that may be utilized by other body tissues.
Immediately following a meal, there is more glucose, a simple sugar, in the circulation than is required by the cells. Most of this simple sugar is converted by the liver back into glycogen, a more complex molecule that is then stored in the liver. The liver can swiftly change these glycogen stores back into glucose for use as a cellular energy source once the available glucose in the bloodstream is depleted. This system aids in preventing significant changes in the glucose supply between meals. The glycogen stores inside the liver continue to accumulate, which can result in what is usually referred to as a "fatty liver," and over time this can even interfere with the regular activities of the liver, if sugar and fat intake continuously exceeds the needs of the body.
The body converts extra nutrients into fat for long-term storage when the total amount of nutrients consumed continuously outweighs the body's material and energy requirements. All surplus nutritional types, even pure protein, are included in this. Do not believe the myth that sweet, starchy, or fatty meals are the only sources of fat. Chemical processes that take place in the liver can convert extra amino acids into glucose, which is ultimately transformed into fat.
Adipose tissue, the medical word for fat that has been stored, may be found in almost every area of the body. Age, gender, heredity, and, of course, the amount of extra fat present all play a role in the precise location and distribution of the body's primary fat stores. The "apple" and "pear" shapes of the body, round faces, large abdomens, and all the other external characteristics we identify with obesity can be produced by significant deposits of adipose tissue. These fat reserves may be activated and the body's shape will change if the amount of nutrients consumed falls short of what the body requires.
It's crucial to understand that not all adipose tissue develops in the body's obvious spots. Around the body's primary organs are also where fatty deposits can be seen. These so-called visceral fat deposits, particularly those near the heart, might actually obstruct the organ's ability to operate normally.
The bottom line is that a healthy diet is one that consistently satisfies the body's nutritional requirements without going beyond. It goes without saying that excessive eating results in excessive fat storage, which is probably why you are reading this book.
Waste Control
Not all of the food we consume is healthy. That holds true even for those who insist they exclusively consume nutritious foods with a high nutritional value. Some substances simply cannot be digested and pass through the intestine without being absorbed. Roughage is the term we use to describe this type of stuff, and some of it is beneficial to us. Every meal we consume passes through the
Anything that is not absorbed enters the large intestine for eventual evacuation from the small intestine.
The purpose of the large intestine, often known as the colon, is to concentrate the waste by absorbing the majority of its water. This happens as the waste travels through the colon's five to six feet before being expelled from the body through the anus as feces.
The waste would be quite little and result in small, hard stools if it weren't for a certain quantity of roughage. The colon must produce pressures that are far higher than usual in order to drive that type of fecal material along. Over time, diverticulitis, a frequent illness, is mostly brought on by those high pressures. Therefore, including some roughage in your diet is undoubtedly a smart idea.
Summary
Even though eating is among the most straightforward and fundamental human behaviors, the digestive process is actually rather intricate. It is necessary to disassemble the foods we eat into their fundamental molecular parts. The liver then detoxifies and chemically transforms them into the body's usable building blocks and energy sources. Any nutrients that are taken by the colon but are not immediately utilized are stored as fat. Whatever is not absorbed is released as trash. It's a good thing the procedure is automated.
It's time to examine various weight-loss surgical procedures, how those adjustments function, and what the dangers and rewards are now that you have seen the fundamental parts and functions of the digestive system.