The Digestive system

Teeth

Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones.

The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. There are also two solid digestive organs, the liver and the pancreas, which produce juices that reach the intestine through small tubes. In

addition, parts of other organ systems (for instance, nerves and blood) play a major role in the digestive system.

The esophagus (oesophagus) is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach. The word esophagus is derived from the Latin œsophagus, which derives from the Greek word oisophagos, lit. "entrance for eating." In humans the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra. The esophagus passes through posterior mediastinum in thorax and enters abdomen through a hole in the diaphragm at the level of the tenth thoracic vertebrae (T10). It is usually about 10–50 cm long depending on individual height. It is divided into cervical, thoracic and abdominal parts. Due to the inferior pharyngeal constrictor muscle, the entry to the esophagus opens only when swallowing or vomiting.

The large intestine (or "large bowel") is the third-to-last part of the digestive system in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body.[1] This article is primarily about the human gut, though the information about its processes are directly applicable to most mammal

The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to describe the entire intestine. This article is primarily about the human gut, though the information about its processes is directly applicable to most placental mammals. The primary function of the small intestine is the absorption of nutrients and minerals found in food

Normal Function of the Esophagus

The esophagus seems to have only one important function in the body—to carry food, liquids, and saliva from the mouth to the stomach. The stomach then acts as a container to start digestion and pump food and liquids into the intestines in a controlled process. Food can then be properly digested over time, and nutrients can be absorbed by the intestines.

The esophagus transports food to the stomach by coordinated contractions of its muscular lining. This process is automatic and people are usually not aware of it. Many people have felt their esophagus when they swallow something too large, try to eat too quickly, or drink very hot or very cold liquids. They then feel the movement of the food or drink down the esophagus into the stomach, which may be an uncomfortable sensation.

The muscular layers of the esophagus are normally pinched together at both the upper and lower ends by muscles called sphincters. When a person swallows, the sphincters relax automatically to allow food or drink to pass from the mouth into the stomach. The muscles then close rapidly to prevent the swallowed food or drink from leaking out of the stomach back into the esophagus or into the mouth. These sphincters make it possible to swallow while lying down or even upside-down. When people belch to release swallowed air or gas from carbonated beverages, the sphincters relax and small amounts of food or drink may come back up briefly; this condition is called reflux. The esophagus quickly squeezes the material back into the stomach. This amount of reflux and the reaction to it by the esophagus are considered normal.

While these functions of the esophagus are obviously an important part of everyday life, people who must have their esophagus removed, for example because of cancer, can live a relatively healthy life without it.

Human Digestive System

Digestive System Label Me! Printout (Simple version)Digestive System Label Me! Printout

The human digestive system is a complex series of organs and glands that processes food. In order to use the food we eat, our body has to break the food down into smaller molecules that it can process; it also has to excrete waste.

Most of the digestive organs (like the stomach and intestines) are tube-like and contain the food as it makes its way through the body. The digestive system is essentially a long, twisting tube that runs from the mouth to the anus, plus a few other organs (like the liver and pancreas) that produce or store digestive chemicals.

The Digestive Process:The start of the process - the mouth: The digestive process begins in the mouth. Food is partly broken down by the process of chewing and by the chemical action of salivary enzymes (these enzymes are produced by the salivary glands and break down starches into smaller molecules).

On the way to the stomach: the esophagus - After being chewed and swallowed, the food enters the esophagus. The esophagus is a long tube that runs from the mouth to the stomach. It uses rhythmic, wave-like muscle movements (called peristalsis) to force food from the throat into

the stomach. This muscle movement gives us the ability to eat or drink even when we're upside-down.

In the stomach - The stomach is a large, sack-like organ that churns the food and bathes it in a very strong acid (gastric acid). Food in the stomach that is partly digested and mixed with stomach acids is called chyme.

In the small intestine - After being in the stomach, food enters the duodenum, the first part of the small intestine. It then enters the jejunum and then the ileum (the final part of the small intestine). In the small intestine, bile (produced in the liver and stored in the gall bladder), pancreatic enzymes, and other digestive enzymes produced by the inner wall of the small intestine help in the breakdown of food.

In the large intestine - After passing through the small intestine, food passes into the large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) are removed from the food. Many microbes (bacteria like Bacteroides, Lactobacillus acidophilus, Escherichia coli, and Klebsiella) in the large intestine help in the digestion process. The first part of the large intestine is called the cecum (the appendix is connected to the cecum). Food then travels upward in the ascending colon. The food travels across the abdomen in the transverse colon, goes back down the other side of the body in the descending colon, and then through the sigmoid colon.

The end of the process - Solid waste is then stored in the rectum until it is excreted via the anus.

Digestive System Glossary:abdomen - the part of the body that contains the digestive organs. In human beings, this is between the diaphragm and the pelvisalimentary canal - the passage through which food passes, including the mouth, esophagus, stomach, intestines, and anus.Anus - the opening at the end of the digestive system from which feces (waste) exits the body.Appendix - a small sac located on the cecum.ascending colon - the part of the large intestine that run upwards; it is located after the cecum.bile - a digestive chemical that is produced in the liver, stored in the gall bladder, and secreted into the small intestine.cecum - the first part of the large intestine; the appendix is connected to the cecum.chyme - food in the stomach that is partly digested and mixed with stomach acids. Chyme goes on to the small intestine for further digestion.descending colon - the part of the large intestine that run downwards after the transverse colon and before the sigmoid colon.digestive system - (also called the gastrointestinal tract or GI tract) the system of the body that processes food and gets rid of waste.duodenum - the first part of the small intestine; it is C-shaped and runs from the stomach to the jejunum.epiglottis - the flap at the back of the tongue that keeps chewed food from going down the windpipe to the lungs. When you swallow, the epiglottis automatically closes. When you breathe, the epiglottis opens so that air can go in and out of the windpipe.

Esophagus - the long tube between the mouth and the stomach. It uses rhythmic muscle movements (called peristalsis) to force food from the throat into the stomach.gall bladder - a small, sac-like organ located by the duodenum. It stores and releases bile (a digestive chemical which is produced in the liver) into the small intestine.gastrointestinal tract - (also called the GI tract or digestive system) the system of the body that processes food and gets rid of waste.Ileum - the last part of the small intestine before the large intestine begins.Intestines - the part of the alimentary canal located between the stomach and the anus.jejunum - the long, coiled mid-section of the small intestine; it is between the duodenum and the ileum.Liver - a large organ located above and in front of the stomach. It filters toxins from the blood, and makes bile (which breaks down fats) and some blood proteins.mouth - the first part of the digestive system, where food enters the body. Chewing and salivary enzymes in the mouth are the beginning of the digestive process (breaking down the food).pancreas - an enzyme-producing gland located below the stomach and above the intestines. Enzymes from the pancreas help in the digestion of carbohydrates, fats and proteins in the small intestine.peristalsis - rhythmic muscle movements that force food in the esophagus from the throat into the stomach. Peristalsis is involuntary - you cannot control it. It is also what allows you to eat and drink while upside-down.rectum - the lower part of the large intestine, where feces are stored before they are excreted.salivary glands - glands located in the mouth that produce saliva. Saliva contains enzymes that break down carbohydrates (starch) into smaller molecules.sigmoid colon - the part of the large intestine between the descending colon and the rectum.stomach - a sack-like, muscular organ that is attached to the esophagus. Both chemical and mechanical digestion takes place in the stomach. When food enters the stomach, it is churned in a bath of acids and enzymes.transverse colon - the part of the large intestine that runs horizontally across the abdomen.

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Digestive System (simple version)Label the digestive system.

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Digestive SystemLabel the digestive system.

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How digest.

We all need food to help us grow, but how do we turn an apple, a sandwich or a cupcake into something useful to our bodies?  We digest it.  We break it down into pieces our body can use – pieces like sugar and fats for energy, and protein for muscles.

Digestion begins right when we eat food.  Our teeth and our saliva (our spit!) break food down and allow us to swallow it.  The food is then carried down a long pipe – called the “esophagus” – to the stomach.

Our stomachs grind and mash up our food into a mushy goop called “chime.”  Once food is in this mushy form, our body is ready to pull out the nutrients (the healthy bits!).  To do this, the food leaves the stomach and goes into a long tube called the small intestine.

It’s a journey of about 20 feet! And it’s all coiled up inside you.  This is where most digestion takes place. Food continues to be broken down even more! The small intestine pulls out the nutrients, which are sent out to the rest of our bodies to help us grow!

Our bodies can’t use all of the food we eat. What’s left over is waste.  After the leftovers leave the small intestine, they enter the large intestine. There, the watery part of the waste is removed and only the solid, or hard parts, remain. Since our bodies can’t use them, we have to get rid of them. After the large intestine, there’s nowhere else to go but out!  This is when you head to the bathroom!

The whole process can take between one and three days.   Your apple, your sandwich, or your cupcake has become something you flush away in the toilet! (Only after your body has taken out all of the nutrients it will use as fuel to move and grow.)

The Process of Digestion

Two Stages Of Digestion

Food is digested in two stages. The first stage involves the bolus (where the concentration of enzymes is low) as it moves along the alimentary tract. At this stage, the food is subjected to primary treatment, the boluses are first broken down into smaller ones and these in turn become separate molecules.

The main process of digestion (the breakdown of molecules) occurs at the second stage when digestion takes place in the intestine near the intestinal wall. This type of digestion, called parietal digestion, is very good for the organism. The first advantage, which has already been mentioned, is that it is possible to attain a very high rate of digestion with only small amounts of enzymes. The other advantage is that the digestive enzymes can be used sparingly. The enzymes that are adsorbed on the intestinal wall are preserved and continue to serve the organism for a long time, while those from the bolus are eliminated together with the remains of the undigested food and are thus lost. The third and final advantage is that the completely digested food, which is ready to be absorbed by the blood, appears to be just where absorption takes place, i. e. close to the intestinal wall. This greatly accelerates and improves absorption.

This discovery allowed another mystery to be solved. Physicians have long been aware that sometimes in some humans the alimentary glands almost stop function as a result of illness. The

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sick person does not notice this since it almost does not aftect his digestion. How the food was digested remained a puzzle. Now it has been discovered that the negligible amounts of enzymes secreted by a faulty gland are adsorbed by the intestinal wall, accumulated and retained, thus ensuring the normal digestion of food.

July 9, 2010 at 9:35 am under Food and Digestion.Tags: alimentary tract, bolus, digestion, enzymes, food, intestinal wall, process of digestionComment on this post.

Diet Management and Digestion

On the spur of the moment many of us would want to go on a diet in order to stay healthy and fit.

However, it is necessary to emphasize that you should know the objective of your diet management which might include one or all of the following:

If you are diabetic, you need to control the levels of glucose in blood and prevent loss of glucose in urine.

Achievement of a satisfactory weight. Overweight is indeed a health hazard particularly for diabetics. If you are under-weight, you will need to increase your body weight.

Provision of a palatable diet which is acceptable to each individual. Getting sufficient calories for normal activities.

Once the objectives are clear, the next step is to:

Develop the diet plan relative to each person depending on his/her age, weight, height and activity. The planned diet should take into account the individual’s economic status, availability and cost of food items, national, religious and social customs, personal idiosyncrasies, occupation, facilities for preparing and obtaining meals and so on.

Define whether the person is diabetic or not. Determine the nutritional requirements of the person.

Unfortunately, we still see people eating the same food over and over again. They simply resist changing their nutritional habits for their benefit.

However, it is important to understand the following : “ Eating well, while eating right; Eating right is half the fight!”

What it means here is that you can have a free choice for possible substitutions in your diet instead of  sticking to the same program. Just make sure you meet your objectives.

April 1, 2010 at 10:05 pm under Diet.Tags: body weight, diabetic, diet management, diet plan, foodComment on this post.

Lower Your Cholesterol

Cholesterol has mistakenly been shown the main villain in heart disease whereas the fact is that one type is good for you!

In fact:

Studies show that foods high in cholesterol don’t raise the cholesterol level An increase of the good type of cholesterol – HDL – is good for your heart A diet high in vegetables and soy can lead to a reduction in cholesterol level Niacin (vitamin B3) supplements can also lower the bad cholesterol level

The hype about cholesterol started after a scientist found that rabbits developed heart disease after being fed cholesterol. He didn’t realize that because rabbits are vegetarians they have no means of dealing with animal fat.

Recent controlled tests have shown that an increase in the consumption of shrimps and eggs, which are high in cholesterol, do not lead to an increase in levels.

However, this doesn’t mean you can go out and binge on cholesterol. The problem is that foods high in cholesterol are mostly high in saturated fats, which most definitely are bad for hearts and arteries.

A complication with cholesterol is that there are two types: HDL cholesterol (high density lipoprotein) and LDL cholesterol (low density lipoprotein).

If you have a high cholesterol level, and much of it is LDL cholesterol, you’re at high risk for heart disease. A relatively high level of HDL usually means low risk. If your HDL makes up one-fifth of your amount of cholesterol you have average risk of heart disease – this is a ratio of cholesterol to HDL of 5:1. With only one-eighth of HDL you’re at high risk. If HDL accounts for one-third you’re low risk (3:1).

However, having a very small amount of cholesterol in your body is not good news either! People with low levels have been found to lead to strokes and to cause anti-social behavior.

How do you lower a high level of cholesterol? A recent report showed that a diet high in soy products, beans and vegetables, and without meat or fish could lower the level as much as some medications.

Nutritional supplements lower cholesterol levels. Also, recent studies show that taking fairly large amounts of niacin (B3) can have more effect than the cholesterol-lowering drugs gemfribrozil and lovastatin in reducingl levels. They do this by increasing the HDL level, while reducing total cholesterol levels.

However, if you take 500-1,500mg niacin, which you need to reduce cholesterol levels,  you may find that you get flushed uncomfortably. You can overcome this by taking the supplement in smaller doses three times a day, or by taking ‘no-flush niacin’.

So, if you are at risk with high cholesterol make sure that it is LDL cholesterol that is relatively high, and take a niacin supplement. Of course, never abandon medications without the advice of a doctor. Niacin and cholesterol-lowering drugs have been found to work well together.

March 8, 2010 at 12:55 pm under Diet.Tags: cholesterol, cholesterol level, food, HDL, heart disease, LDLComment on this post.

Benefits of Biotin for Digestive System

Biotin is an important vitamin for proper digestion. It affects processing of most food. Biotin works with some other B vitamins to carry out essential functions, and is part of the vitamin B family, all of which are important to health. It is soluble in water, so you need some every day.

Biotin affects the processing of protein, fats and carbohydrates – that’s almost all of your main foodstuffs. For example, these processes include building amino acids into protein, getting energy from glucose. It also helps convert folic acid (folacin) into its active form so that it can do its work!

Severe deficiency of biotin is fairly rare, but various factors can prevent proper absorption of biotin. Infants can develop deficiency in biotin, however. In adults, antibiotics can result in deficiency of biotin, and some other vitamins.

Another cause of deficiency is the consumption of raw egg white in foods such as chocolate mousse. Biotin is not affected by cooked eggs. One reason that severe deficiency of biotin is rare is that the some biotin is synthesised in the intestine.

Although severe deficiency is rare, many Americans don’t get enough biotin to maintain good health, and a supplement should contain at least 50 mcg, and 100-200 mcg biotin is better. In fact, the majority of people don’t get enough vitamins, particularly B vitamins to maintain good health.

To get the benefits of biotin and enjoy life more, you can take either a vitamin B complex supplement, or better a multi-vitamin-mineral supplement which contains all B vitamins.

February 11, 2010 at 9:43 pm under Vitamins.Tags: B vitamins, biotin, digestion, food, health, proteinComment on this post.

Enzymes And Chemical Reactions

An experiment was carried out. A piece of intestine was placed for some time in a test tube containing a starch solution. The idea was that if the intestine contained digestion-accelerating substances, they would be secreted into the test tube. The intestine was then removed and some amylase added to the starch. Digestion proceeded slowly, just as in the original experiments.

Perhaps the piece of intestine did not have enough time to secrete the substance it was supposed to have. Yet another experiment was carried out. An extract was obtained from the intestine of a slaughtered animal. The extract should, no doubt, have contained the required substance.

However, when the extract was added to the test tube containing the starch and amylase, it did not accelerate the rate of digestion. This meant that the intestinal wall did not contain substances accelerating the process of digestion. What then triggered off the process?

The puzzle was solved unexpectedly. It was the very structure of the intestinal wall that facilitated the process of digestion. The surface of the epithelial cells lining the intestine carries ultra-microscopic shoots. Each cell carries as many as three thousand shoots, and this makes the surface area of the intestine very extensive, enabling it to adsorb, i. e. precipitate and retain, a great many enzymes. These enzymes act as catalysts accelerating chemical reactions. The enzymes interact chemically with the reagents, but as soon as the reaction is complete, they regain their previous chemical composition. This explains why even small amounts of catalysts markedly accelerate the rate of chemical reactions.

It is only natural that digestion is more energetic on the surface of the intestinal wall where the concentration of enzymes is much greater than within the mass of food. The total amount of enzymes may not be large; they can be used again and again. What is important is their extremely high concentration and this is why even moderate amounts of enzymes ensure a high rate of digestion.

January 3, 2010 at 11:12 am under Food and Digestion.Tags: amylase, catalysts, digestion, enzymes, food, intestinal wall, intestine, process of digestion, starch, test tubeComment on this post.

Intestinal Wall Accelerate Digestion

It was not easy to study the process of digestion. It was as late as the turn of the last century that the Russian scientist Ivan Petrovich Pavlov completed a detailed study of the main alimentary glands. They turned out to be numerous and, what is more, it was discovered that for each type of food they produce a special composition of digestive juices. Academician Pavlov was awarded the Nobel prize, the highest international award, for these investigations. Thus, the basic mystery surrounding the process of digestion seemed to have been unveiled. However, the discovery was not yet complete. Nobody could reproduce the entire process of digestion in the laboratory by pouring into a test tube the necessary digestive juices in the correct sequence, and thus imitating the process observed in living organisms under natural conditions. The food was

also digested in the test tube, but the process was all too slow, much slower than in the alimentary tract.

Recently, scientists have succeeded in uncovering this mystery. An astonishing thing is that the food which comes into contact with the intestinal wall is digested much more quickly than that incorporated in the main mass of food. This is similar to what happens when food is fried in a pan: the food in immediate contact with the walls of the pan cooks much more quickly. This is quite understandable, for the pan is much hotter than the food. But the intestinal wall is not at all hot, so why then does it accelerate digestion?

The first thing was to find out whether the intestinal wall ready accelerated digestion. With this in view, the following experiment was carried out. A piece of intestine from a freshly killed animal was placed in one of two test tubes containing equal amounts of a mixture of starch and an amylase (a starch-splitting enzyme). Splitting of the starch proceeded much more rapidly around the piece of intestine which proved that the intestinal wall did accelerate digestion. But how does this happen?

January 2, 2010 at 6:16 pm under Food and Digestion.Tags: alimentary tract, digestion, digestive juices, food, intestinal wall, process of digestionComment on this post.

Food and Stomachs

Even primitive people knew that the food eaten by man and animals is digested in their stomachs. When skinning their game, they were sure to peep into the stomachs. Even nowadays almost no housewife can resist the temptation of learning what the pike had for dinner and whether the chicken’s stomachs contain anything of interest besides small stones and sand. When hunters cut up their prey, they found in the stomachs and intestine neither meat, nor grass or seeds, but a pasty mass, as though the food had been cooked there.

It took man a long time to find out what really occurs. The food is not changed under the influence of heat: the temperature in the stomachs of even the ‘hottest’ warmblooded animals is no higher than 38-43°C and this is not sufficient to cook food. Digestion takes place with the aid of digestive juices containing special enzymes.

The alimentary tract of man and animals is a complex chemical laboratory. The food consumed is ground, mixed with various digestive juices and moves gradually from one part to another. In each part the food is held long enough for it to be digested, being saturated with special substances. These substances are absorbed during the digestive process, that is, during the breakdown of complex chemical substances into simple ones (proteins into amino acids, fats into glycerol and fatty acids, carbohydrates into monosaccharides). What cannot be digested and used by the organism is disposed of.

December 31, 2009 at 2:42 pm under Food and Digestion.Tags: animals, chemical substances, digestion, digestive juices, digestive process, food, stomachs1 Comment.

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How teeth help to digest

The digestive system is made up of the digestive tract—a series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food.

Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, large intestine—also called the colon—rectum, and anus. Inside these hollow organs is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. The digestive tract also contains a layer of smooth muscle that helps break down food and move it along the tract.

Two “solid” digestive organs, the liver and the pancreas, produce digestive juices that reach the intestine through small tubes called ducts. The gallbladder stores the liver's digestive juices until they are needed in the intestine. Parts of the nervous and circulatory systems also play major roles in the digestive system.

Digestion is basically the break down of chemicals into smaller parts in the body so that they are absorbed by the blood. The process of digestion in human beings is a complex process that involves many organs.

The food enters the body through the mouth which is also known as the oral cavity. In the oral cavity the food is chewed. Saliva is produced in the oral cavity by salivary glands and is mixed with the chewed food by the tongue. After chewing food is swallowed whereby it enters the Esophagus which consists of oropharynx and hypopharynx.

Through the esophagus the food passes through the cardiac orifice and then enters the stomach. Food is then broken down and mixed with gastric acis and digestive enzymes. Food takes on semi liquid form and the essential elements are absorbed in the blood stream.

From the stomach, the food is passed on to the small intestine through the Pyloric Sphincter. Major portion of digestion and absorption occurs here as the chyme enters the duodenum. It is mixed with bile, Pancreatic juice and intestinal enzymes. Most of the nutrients are absorbed through small intestine.

From the small intestine, the food is passed on to the large intestine. Water is absorbed from the Bolus and feaces is stored for egestion in the rectum. This food is egested through the anus.