Digestive system


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Digestive system

  1. 1. The Digestive system
  2. 2. TeethDigestion is the mechanical and chemical breakdown of food into smaller components that are moreeasily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown oflarge food molecules to smaller ones.The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to theanus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, themucosa contains tiny glands that produce juices to help digest food. There are also two solid digestiveorgans, the liver and the pancreas, which produce juices that reach the intestine through small tubes. In
  3. 3. addition, parts of other organ systems (for instance, nerves and blood) play a major role in the digestivesystem.The esophagus (oesophagus) is an organ in vertebrates which consists of a muscular tube through whichfood passes from the pharynx to the stomach. During swallowing, food passes from the mouth throughthe pharynx into the esophagus and travels via peristalsis to the stomach. The word esophagus isderived from the Latin œsophagus, which derives from the Greek word oisophagos, lit. "entrance foreating." In humans the esophagus is continuous with the laryngeal part of the pharynx at the level of theC6 vertebra. The esophagus passes through posterior mediastinum in thorax and enters abdomenthrough 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. Dueto the inferior pharyngeal constrictor muscle, the entry to the esophagus opens only when swallowingor vomiting.The large intestine (or "large bowel") is the third-to-last part of the digestive system in vertebrateanimals. Its function is to absorb water from the remaining indigestible food matter, and then to passuseless waste material from the body.[1] This article is primarily about the human gut, though theinformation about its processes are directly applicable to most mammalThe small intestine is the part of the gastrointestinal tract following the stomach and followed by thelarge intestine, and is where much of the digestion and absorption of food takes place. In invertebratessuch as worms, the terms "gastrointestinal tract" and "large intestine" are often used to describe theentire intestine. This article is primarily about the human gut, though the information about itsprocesses is directly applicable to most placental mammals. The primary function of the small intestineis the absorption of nutrients and minerals found in foodNormal Function of the EsophagusThe esophagus seems to have only one important function inthe body—to carry food, liquids, and saliva from the mouth tothe stomach. The stomach then acts as a container to startdigestion and pump food and liquids into the intestines in acontrolled process. Food can then be properly digested overtime, and nutrients can be absorbed by the intestines.The esophagus transports food to the stomach by coordinatedcontractions of its muscular lining. This process is automaticand people are usually not aware of it. Many people have felt their esophagus when they swallowsomething too large, try to eat too quickly, or drink very hot or very cold liquids. They then feelthe movement of the food or drink down the esophagus into the stomach, which may be anuncomfortable sensation.
  4. 4. The muscular layers of the esophagus are normally pinched together at both the upper and lowerends by muscles called sphincters. When a person swallows, the sphincters relax automatically toallow food or drink to pass from the mouth into the stomach. The muscles then close rapidly toprevent the swallowed food or drink from leaking out of the stomach back into the esophagus orinto 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, thesphincters relax and small amounts of food or drink may come back up briefly; this condition iscalled reflux. The esophagus quickly squeezes the material back into the stomach. This amountof 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, peoplewho must have their esophagus removed, for example because of cancer, can live a relativelyhealthy life without it. Human Digestive Digestive System Label Me! Printout (Simple version) System 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 partlybroken down by the process of chewing and by the chemical action of salivary enzymes (theseenzymes 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 foodenters the esophagus. The esophagus is a long tube that runs from the mouth to the stomach. Ituses rhythmic, wave-like muscle movements (called peristalsis) to force food from the throat intothe stomach. This muscle movement gives us the ability to eat or drink even when were upside-down.
  5. 5. In the stomach - The stomach is a large, sack-like organ that churns the food and bathes it in avery strong acid (gastric acid). Food in the stomach that is partly digested and mixed withstomach acids is called chyme.In the small intestine - After being in the stomach, food enters the duodenum, the first part ofthe small intestine. It then enters the jejunum and then the ileum (the final part of the smallintestine). 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 smallintestine help in the breakdown of food.In the large intestine - After passing through the small intestine, food passes into the largeintestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) areremoved 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 partof the large intestine is called the cecum (the appendix is connected to the cecum). Food thentravels upward in the ascending colon. The food travels across the abdomen in the transversecolon, goes back down the other side of the body in the descending colon, and then through thesigmoid 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 isbetween 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 secretedinto 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 goeson to the small intestine for further digestion.descending colon - the part of the large intestine that run downwards after the transverse colonand before the sigmoid colon.digestive system - (also called the gastrointestinal tract or GI tract) the system of the body thatprocesses food and gets rid of waste.duodenum - the first part of the small intestine; it is C-shaped and runs from the stomach to thejejunum.epiglottis - the flap at the back of the tongue that keeps chewed food from going down thewindpipe to the lungs. When you swallow, the epiglottis automatically closes. When youbreathe, 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 musclemovements (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
  6. 6. 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 thatprocesses 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 theileum.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 salivaryenzymes 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 smallintestine.peristalsis - rhythmic muscle movements that force food in the esophagus from the throat intothe stomach. Peristalsis is involuntary - you cannot control it. It is also what allows you to eatand 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 thatbreak 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 andmechanical digestion takes place in the stomach. When food enters the stomach, it is churned ina bath of acids and enzymes.transverse colon - the part of the large intestine that runs horizontally across the abdomen.Related Pages: Digestive System (simple version) Digestive System Label the digestive system. Label the digestive system. Answers AnswersHow digest.We all need food to help us grow, but how do we turn an apple, a sandwich or a cupcake intosomething 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 fooddown and allow us to swallow it. The food is then carried down a long pipe – called the―esophagus‖ – to the stomach.
  7. 7. Our stomachs grind and mash up our food into a mushy goop called “chime.” Once food isin 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 digestiontakes place. Food continues to be broken down even more! The small intestine pulls out thenutrients, 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 leavethe small intestine, they enter the large intestine. There, the watery part of the waste is removedand only the solid, or hard parts, remain. Since our bodies can‘t use them, we have to get rid ofthem. After the large intestine, there‘s nowhere else to go but out! This is when you head to thebathroom!The whole process can take between one and three days. Your apple, your sandwich, or yourcupcake has become something you flush away in the toilet! (Only after your body has taken outall of the nutrients it will use as fuel to move and grow.)The Process of Digestion s earc h...Two Stages Of DigestionFood is digested in two stages. The first stage involves the bolus (where the concentration ofenzymes is low) as it moves along the alimentary tract. At this stage, the food is subjected toprimary treatment, the boluses are first broken down into smaller ones and these in turn becomeseparate molecules.The main process of digestion (the breakdown of molecules) occurs at the second stage whendigestion takes place in the intestine near the intestinal wall. This type of digestion, calledparietal digestion, is very good for the organism. The first advantage, which has already beenmentioned, is that it is possible to attain a very high rate of digestion with only small amounts ofenzymes. The other advantage is that the digestive enzymes can be used sparingly. The enzymesthat are adsorbed on the intestinal wall are preserved and continue to serve the organism for along time, while those from the bolus are eliminated together with the remains of the undigestedfood and are thus lost. The third and final advantage is that the completely digested food, whichis ready to be absorbed by the blood, appears to be just where absorption takes place, i. e. closeto the intestinal wall. This greatly accelerates and improves absorption.This discovery allowed another mystery to be solved. Physicians have long been aware thatsometimes in some humans the alimentary glands almost stop function as a result of illness. Thesick person does not notice this since it almost does not aftect his digestion. How the food wasdigested remained a puzzle. Now it has been discovered that the negligible amounts of enzymessecreted by a faulty gland are adsorbed by the intestinal wall, accumulated and retained, thusensuring the normal digestion of food.
  8. 8. 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 DigestionOn 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 dietmanagement 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 resistchanging their nutritional habits for their benefit.However, it is important to understand the following : ― Eating well, while eating right; Eatingright is half the fight!‖What it means here is that you can have a free choice for possible substitutions in your dietinstead 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 CholesterolCholesterol has mistakenly been shown the main villain in heart disease whereas the fact is thatone type is good for you!In fact:
  9. 9. 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 levelThe hype about cholesterol started after a scientist found that rabbits developed heart diseaseafter being fed cholesterol. He didn‘t realize that because rabbits are vegetarians they have nomeans 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 foodshigh in cholesterol are mostly high in saturated fats, which most definitely are bad for hearts andarteries.A complication with cholesterol is that there are two types: HDL cholesterol (high densitylipoprotein) 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 forheart disease. A relatively high level of HDL usually means low risk. If your HDL makes upone-fifth of your amount of cholesterol you have average risk of heart disease – this is a ratio ofcholesterol to HDL of 5:1. With only one-eighth of HDL you‘re at high risk. If HDL accountsfor 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 soyproducts, beans and vegetables, and without meat or fish could lower the level as much as somemedications.Nutritional supplements lower cholesterol levels. Also, recent studies show that taking fairlylarge amounts of niacin (B3) can have more effect than the cholesterol-lowering drugsgemfribrozil and lovastatin in reducingl levels. They do this by increasing the HDL level, whilereducing total cholesterol levels.However, if you take 500-1,500mg niacin, which you need to reduce cholesterol levels, you mayfind that you get flushed uncomfortably. You can overcome this by taking the supplement insmaller 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 relativelyhigh, and take a niacin supplement. Of course, never abandon medications without the advice ofa doctor. Niacin and cholesterol-lowering drugs have been found to work well together.
  10. 10. 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 SystemBiotin is an important vitamin for proper digestion. It affects processing of most food. Biotinworks with some other B vitamins to carry out essential functions, and is part of the vitamin Bfamily, 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 mainfoodstuffs. For example, these processes include building amino acids into protein, gettingenergy from glucose. It also helps convert folic acid (folacin) into its active form so that it can doits work!Severe deficiency of biotin is fairly rare, but various factors can prevent proper absorption ofbiotin. Infants can develop deficiency in biotin, however. In adults, antibiotics can result indeficiency of biotin, and some other vitamins.Another cause of deficiency is the consumption of raw egg white in foods such as chocolatemousse. Biotin is not affected by cooked eggs. One reason that severe deficiency of biotin is rareis that the some biotin is synthesised in the intestine.Although severe deficiency is rare, many Americans don‘t get enough biotin to maintain goodhealth, and a supplement should contain at least 50 mcg, and 100-200 mcg biotin is better. Infact, the majority of people don‘t get enough vitamins, particularly B vitamins to maintain goodhealth.To get the benefits of biotin and enjoy life more, you can take either a vitamin B complexsupplement, 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 ReactionsAn experiment was carried out. A piece of intestine was placed for some time in a test tubecontaining a starch solution. The idea was that if the intestine contained digestion-acceleratingsubstances, they would be secreted into the test tube. The intestine was then removed and someamylase 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 supposedto have. Yet another experiment was carried out. An extract was obtained from the intestine of aslaughtered animal. The extract should, no doubt, have contained the required substance.
  11. 11. However, when the extract was added to the test tube containing the starch and amylase, it didnot accelerate the rate of digestion. This meant that the intestinal wall did not contain substancesaccelerating the process of digestion. What then triggered off the process?The puzzle was solved unexpectedly. It was the very structure of the intestinal wall thatfacilitated the process of digestion. The surface of the epithelial cells lining the intestine carriesultra-microscopic shoots. Each cell carries as many as three thousand shoots, and this makes thesurface area of the intestine very extensive, enabling it to adsorb, i. e. precipitate and retain, agreat many enzymes. These enzymes act as catalysts accelerating chemical reactions. Theenzymes interact chemically with the reagents, but as soon as the reaction is complete, theyregain their previous chemical composition. This explains why even small amounts of catalystsmarkedly accelerate the rate of chemical reactions.It is only natural that digestion is more energetic on the surface of the intestinal wall where theconcentration of enzymes is much greater than within the mass of food. The total amount ofenzymes may not be large; they can be used again and again. What is important is theirextremely high concentration and this is why even moderate amounts of enzymes ensure a highrate 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 DigestionIt was not easy to study the process of digestion. It was as late as the turn of the last century thatthe Russian scientist Ivan Petrovich Pavlov completed a detailed study of the main alimentaryglands. They turned out to be numerous and, what is more, it was discovered that for each typeof food they produce a special composition of digestive juices. Academician Pavlov wasawarded the Nobel prize, the highest international award, for these investigations. Thus, the basicmystery surrounding the process of digestion seemed to have been unveiled. However, thediscovery was not yet complete. Nobody could reproduce the entire process of digestion in thelaboratory by pouring into a test tube the necessary digestive juices in the correct sequence, andthus imitating the process observed in living organisms under natural conditions. The food wasalso digested in the test tube, but the process was all too slow, much slower than in thealimentary tract.Recently, scientists have succeeded in uncovering this mystery. An astonishing thing is that thefood which comes into contact with the intestinal wall is digested much more quickly than thatincorporated in the main mass of food. This is similar to what happens when food is fried in apan: the food in immediate contact with the walls of the pan cooks much more quickly. This isquite understandable, for the pan is much hotter than the food. But the intestinal wall is not at allhot, so why then does it accelerate digestion?
  12. 12. The first thing was to find out whether the intestinal wall ready accelerated digestion. With thisin view, the following experiment was carried out. A piece of intestine from a freshly killedanimal was placed in one of two test tubes containing equal amounts of a mixture of starch andan amylase (a starch-splitting enzyme). Splitting of the starch proceeded much more rapidlyaround the piece of intestine which proved that the intestinal wall did accelerate digestion. Buthow 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 StomachsEven primitive people knew that the food eaten by man and animals is digested in theirstomachs. When skinning their game, they were sure to peep into the stomachs. Even nowadaysalmost no housewife can resist the temptation of learning what the pike had for dinner andwhether the chicken‘s stomachs contain anything of interest besides small stones and sand. Whenhunters cut up their prey, they found in the stomachs and intestine neither meat, nor grass orseeds, 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 theinfluence of heat: the temperature in the stomachs of even the ‗hottest‘ warmblooded animals isno higher than 38-43°C and this is not sufficient to cook food. Digestion takes place with the aidof digestive juices containing special enzymes.The alimentary tract of man and animals is a complex chemical laboratory. The food consumedis ground, mixed with various digestive juices and moves gradually from one part to another. Ineach part the food is held long enough for it to be digested, being saturated with specialsubstances. These substances are absorbed during the digestive process, that is, during thebreakdown of complex chemical substances into simple ones (proteins into amino acids, fats intoglycerol and fatty acids, carbohydrates into monosaccharides). What cannot be digested and usedby 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.Recent Posts o Two Stages Of Digestion o Diet Management and Digestion o Lower Your Cholesterol
  13. 13. o Benefits of Biotin for Digestive System o Enzymes And Chemical Reactions Blogroll o Cheap Cigarettes Online o Free Articles Online o Propecia Archives o July 2010 o April 2010 o March 2010 o February 2010 o January 2010 o December 2009 Categories o Diet o Food and Digestion o Vitamins Tags alimentary tract amylase animals biotin body weight bolus B vitamins catalysts chemical substances cholesterol cholesterol level diabetic diet management diet plan digestion digestive juices digestive process enzymes food HDL health heart disease intestinal wall intestine LDL process of digestion protein starch stomachs test tube buy dell notebook battery here LCDScreen notebook displaysEntries (RSS) and Comments (RSS).How teeth help to digestThe digestive system is made up of the digestive tract—a series of hollow organs joined in along, twisting tube from the mouth to the anus—and other organs that help the body break downand absorb food.Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, largeintestine—also called the colon—rectum, and anus. Inside these hollow organs is a lining calledthe mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands thatproduce juices to help digest food. The digestive tract also contains a layer of smooth muscle thathelps break down food and move it along the tract.Two ―solid‖ digestive organs, the liver and the pancreas, produce digestive juices that reach theintestine through small tubes called ducts. The gallbladder stores the livers digestive juices untilthey are needed in the intestine. Parts of the nervous and circulatory systems also play majorroles in the digestive system.
  14. 14. Digestion is basically the break down of chemicals into smaller parts in the body so that they areabsorbed by the blood. The process of digestion in human beings is a complex process thatinvolves many organs.The food enters the body through the mouth which is also known as the oral cavity. In the oralcavity the food is chewed. Saliva is produced in the oral cavity by salivary glands and is mixedwith the chewed food by the tongue. After chewing food is swallowed whereby it enters theEsophagus 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 onsemi 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 ismixed with bile, Pancreatic juice and intestinal enzymes. Most of the nutrients are absorbedthrough small intestine.From the small intestine, the food is passed on to the large intestine. Water is absorbed from theBolus and feaces is stored for egestion in the rectum. This food is egested through the anus.