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Organ Systems - Digestion PowerPoint Presentation

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Description : Check out this medical presentation on Bile Duct Cancer (Cholangiocarcinoma), which is titled "Organ Systems - Digestion", to know about the structure and function of the digestive system, know how absorption of nutrients occur and where in the digestive tract various nutrients are absorbed, identify how the digestive system protects the body from bacteria and toxins, and understand what causes ulcers and food poisoning and how they are prevented and treated.

Tags : Bile Duct Cancer, Cholangiocarcinoma, Organ Systems, Digestion, absorption of nutrients, digestive tract

Published on : May 10, 2021 | Views : 2092 | Downloads : 3

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Organ Systems Digestion
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Navigation Table
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Pre-Test Click a link below to take the pre-test for this unit! Google assessment Digestion
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Introduction Digestion
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Digestion Introduction Digestion Can you imagine having a 30-foot-long tube running from your mouth to your anus? That is exactly what you have in your digestive system. Food contains nutrients like proteins, carbohydrates, and lipids (fats) that the cells in our body use as energy. The process of digestion involves breaking down the food so that cells can use its components to fuel our body and keep it functioning. This unit explains how organisms digest, absorb, and utilize food to obtain the materials they need for their cells to sustain life, grow, and multiply. Usually in biological science, we learn most of what we know from studies of animals. But some of our first notions of what happens in digestion comes from the study of a live human patient who had an unhealed wound that led from the stomach to the outside. Read the interesting Story Time of Dr. Beaumont and his patient.
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After completing this lesson, each student should be able to: Objectives Digestion Understand the structure and function of the digestive system. Explain how absorption of nutrients occur and where in the digestive tract various nutrients are absorbed. Identify how the digestive system protects the body from bacteria and toxins. Understand what causes ulcers and food poisoning and how they are prevented and treated.
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Why It Matters Digestion
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Digestion Why It Matters Why do we need a digestive tract? If the body did not have a digestive tract, you could not enjoy your favorite pizza, hamburger, or other food. The human body must obtain its energy by eating food. Therefore, the main purpose of the digestive system is to provide the body with water, proteins, carbohydrates, lipids (fats), vitamins, and minerals to keep our cells functioning. These essential substances are called nutrients. The digestive system provides these essential nutrients to the 75 trillion cells that live in our bodies. Wow! Do you know how many 75 trillion is? The digestive tract takes both liquids and food and breaks them down into single molecules that can be absorbed by cells in the small intestine. These cells transport the molecules into the bloodstream so that other cells in the body can use them. The digestive tract also serves to eliminate what your body doesn't absorb during the digestive process.
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Digestion Why It Matters Why do I have a stomach? The stomach has two major functions in your body: digestion and defense. (See the illustration on the right.) Digestion breaks down proteins with acidic stomach juice, secreting enzymes that split up proteins into individual amino acids (see Cells Are Us unit on proteins). The defense component kills most foreign organisms that you ingest so that they can't get into your bloodstream or anywhere else in your body. These organisms are destroyed by the highly acidic stomach fluid that is secreted within the stomach.
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Digestion Why It Matters Why do we have two types of intestines? The intestines are where the body absorbs most of the nutrients from food that you eat. The intestines are long, giving your body a greater opportunity to absorb more of what you eat. The small intestine breaks down proteins, carbohydrates, and fats so that they can be absorbed into the body and the bloodstream. The large intestine is where moisture is absorbed from what is left of the food. Anything that is not absorbed by the intestines is then passed through as solid waste (or feces).
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Digestion Why It Matters Why are the liver and pancreas important in digestion? Your liver secretes bile into your small intestine. This bile contains worn out red blood cells that must be removed from the body. If the old red blood cells are not removed, they can become toxic. The bile secreted by your liver also separates the fats that you eat so that they can be broken down by enzymes. (See the picture on the right.) Fat clumps together and when bile is not secreted into the small intestine, your enzymes are less efficient at breaking down fats into their fatty acid components. The enzymes that break down these separated fats come from the pancreas, as do those enzymes that break down carbohydrates and proteins. The pancreas also secretes a basic solution that neutralizes the acidic solution left over from the stomach. The pancreas also secretes insulin, which helps move glucose (blood sugar) from blood into cells. Diabetes is a common and very serious disease that results from lack of insulin. For more information about diabetes, click here.
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What We Know Digestion
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Digestion What We Know Structure and Function of the Digestive System Over the years, scientists have learned a lot about the digestive tract that has given doctors and researchers in the health science field the necessary information to cure or treat most of the digestive disorders that face us today.
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Digestion What We Know Let’s eat some pizza! So, you are hungry and you want to order a pizza! Let’s take a look at the process of eating that pizza, from beginning to end. Pizza contains the three major types of food your body needs to function and some essential vitamins. That sounds good, right? However, pizza is very high in calories and fat. Image from: https://food.unl.edu/recipe/homemade-pizza-crust (To learn more about proteins, carbohydrates, and fats see our Cells are Us module)
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Digestion What We Know What organs are involved in digestion? Before we begin the journey of that pizza through the digestive system, we need an overview of the component of the digestive system. Many organs are involved in the digestive process (see the diagram on the left). First, food enters the body via the mouth, where saliva from the salivary gland begins to break down carbohydrates. Next, the food goes down the food tube, the esophagus, pushed by muscular contractions. The food ends up in the stomach, where stomach acids break down much of the protein into amino acids and kill most bacteria in the food. The liver processes and regulates the substances entering the bloodstream from the food that is ingested. The liver also produces bile, which contains worn-out red blood cells, that is stored in the gall bladder. The pancreas assists in digestion of carbohydrates, proteins, and fats, and it regulates blood sugar levels by directing cells to take up or to secrete sugar into the blood. Once leaving the stomach, the food travels into the small intestine where carbohydrates, amino acids and fats are absorbed. After entering the large intestine, moisture is absorbed from what is left of the food, and bacteria breaks down some of the material that has not been digested. This creates waste (feces). The rectum is the final storage space for wastes, which is what becomes of the food once all of the nutrients and moisture have been removed. The wastes remain in the rectum until excreted. Source: NIH NIDDK
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Digestion What We Know What organs are involved in digestion? Cont’d Source: NIH NIDDK The time food stays in the various parts of the digestive tract in a human under normal conditions is approximately as follows: Stomach: 4-6 hours Small intestine: 2-4 hours Large intestine: 24-48 hours Knowing this, you should be able to answer the following: Why do you get hungry at the times for breakfast, lunch, and dinner? Why should you have a bowel movement every day or two?
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Digestion What We Know Where does the digestive process begin? Let's follow the journey that pizza experiences once it is eaten! First, the mouth begins to chew the pizza. Enzymes in the saliva begin to break down the carbohydrates in the crust. For example, a starch molecule is broken down into glucose molecules by the enzyme, amylase. Modified from: NIH National Cancer Institute From the mouth, the saliva and the tongue work together to prepare the pizza to enter the pharynx. The pharynx directs air to the lungs and food to the stomach. Inside the pharynx is the epiglottis, which covers the opening to the trachea and prevents the food from entering the lungs.
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Digestion What We Know What happens in the stomach? Once through the pharynx, the pizza (or any food you eat) is moved by the actions of smooth muscle in the esophagus to the stomach. The stomach secretes highly acidic gastric juice (pH = 2.5). When you have an upset stomach, it is often because your stomach is not passing the food on into the small intestine, which causes an accumulation of acid in the stomach. The hydrochloric acid (HCl) and enzymes break down the protein components of cheese and pepperoni. Because the proteins are broken down, the peptide bonds between the amino acids are more accessible to the enzymes. The gastric juice also continues the digestion of the crust, started by the saliva. Modified from: NIH National Cancer Institute
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Digestion What We Know Where does the digestive process begin? The pH scale showing a comparison of stomach acid to other known substances. Source: NOAA Muscles in the stomach are working to churn the once solid pizza into a thick liquid. See the Story Time in this unit about how Dr. Beaumont actually observed a lot of this in a living human being! One cell type makes so much HCl that the pH of the stomach goes as low as 2, which means it is VERY acidic. The rest of the body has a pH of 7.2. In other words, the fluid in the stomach is 160,000 times more acidic than the fluid in the rest of your body! Why doesn't the stomach digest itself? The stomach secretes a mucus barrier to protect the stomach lining from the highly acidic contents and from the protein-destroying enzymes. But if this barrier is broken, you get ulcers. See the Hazards section in this unit on ulcers.
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Digestion What We Know What initiates vomiting? Vomiting can be caused by throat or stomach irritation, head trauma, dizziness, intense pain, toxic chemical agents, or emotional factors. The act of vomiting is not directly caused by the stomach but by the contraction of your diaphragm, the muscle below your ribs that is used predominately for breathing, and abdominal muscles. This increases the pressure in the abdominal cavity and pushes the digestive contents out of the stomach and even the duodenum (small intestine) if you vomit strongly. Ever see a green tint in your vomit? What do you suppose that is? You would only see this green when vomiting is especially uncontrollable (hint: what green substance empties into the small intestine?).
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Digestion What We Know What initiates vomiting? Ever have food poisoning? Why didn't the stomach acid destroy the germs that cause food poisoning? The reason is that these particular germs make spores or have acid-resistant shells around them. For more, see Common Hazards section of this unit on food poisoning. Modified from: NIH National Cancer Institute
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Digestion What We Know What happens to food after the stomach? As the pizza, or any other stomach contents, enter the small intestine, the pH is raised back to normal by the pancreatic secretion of sodium bicarbonate (NaHCO3). Due to the acidity of gastric juice, it can be harmful to tissues outside the stomach, since they do not have mucus layers to protect them. Bile, delivered from the liver, makes the fats in the liquid become separated so that enzymes can break them down. Other food materials are broken down by digestive enzymes secreted from the pancreas. The enzymes secreted by the pancreas work to reduce the pepperoni, the cheese, and the crust from your pizza to their simplest forms- amino acids, fatty acids, and sugars, respectively.
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Digestion What We Know What role does the liver play in digestion? Besides making bile, the liver has many other important functions. First, the liver processes the carbohydrates, fats, and proteins absorbed by the small intestine. The liver acts as the detoxification center of the body by breaking down hormones, drugs, and other foreign toxins and also makes the proteins in blood that are responsible for blood clotting. See the Unit on Detoxification in this module for more about the liver. The liver even serves as a storage compartment for the broken-down products of fats, carbohydrates, and many vitamins and minerals. Lastly, the liver removes worn out red blood cells and bacteria from the bloodstream. The worn-out red blood cells are the major component of the bile that is secreted into the digestive tract. More than 500 vital functions have been identified with the liver! As you can tell, the liver is a vital organ - not only for digestion, but for many other systems of the body! Source: NIH NIDDK
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Digestion What We Know What is the role of the pancreas in diabetes? After your body has finished digesting the pizza, your blood glucose (sugar) levels will be high since the small intestine has absorbed the sugars from the starches that were present in your meal. The pancreas recognizes the increase in blood glucose, and it begins to release insulin into the bloodstream. Insulin acts as a gatekeeper for your cells by regulating the flow of glucose into them. Glucagon, on the other hand, functions opposite of insulin. Your liver and muscles store the excess glucose in your blood as glycogen. Whenever your brain senses that blood glucose levels are too low, it triggers the pancreas to release glucagon. Glucagon also serves as a gatekeeper for your cells, triggering cells in your liver and muscles to change glycogen to glucose and to release it into the bloodstream until the blood sugar level has returned to normal. Source: NIH NIDDK
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Digestion What We Know What is the role of the pancreas in diabetes? People with type I diabetes do not make enough insulin in their pancreas. As a result, blood glucose rises. Cells are being starved for glucose because the glucose can't get into cells and stays in the blood. Excess blood glucose also dehydrates cells, because they lose water by osmosis.
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Digestion What We Know What does the large intestine do? Modified from: CDC The large intestine's main function is to remove fluid and salts from the solid waste material that reaches it. By the time that indigestible material from the pizza you ate reaches the large intestine, most nutrients and up to 90% of the water has been absorbed by the small intestine. The remaining water and other key nutrients are absorbed in the first portion of the large intestine and the remaining material forms the feces. The remainder of the large intestine stores the feces that will eventually be pushed by the muscles of the large intestine out of the anus.
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Digestion What We Know A Few Difficulties in Digestion If elimination of the feces is delayed, constipation may occur. Constipation is when there is difficulty with eliminating the feces. When the wastes are retained in the large intestine, large amounts of water will be absorbed by the body, leaving the wastes firm and dry. That can make it tough to go to the bathroom. In contrast, diarrhea is characterized by a highly fluid waste that is caused by an inadequate amount of water absorption by the intestine. Diarrhea can be caused by increased intestinal movement due to bacteria, virus, or stress, an increase in certain substances in the wastes that prevents water from escaping into the blood, or toxins released by cholera bacteria or other microorganisms that increase the secretion of excessive amounts of fluid by cells in the intestine. If there is increased intestinal movement, that can cause cramping.
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Digestion What We Know Good Bacteria Did you know that you have your own fermentation vat in your gut? The large intestine is the home of more than 500 types of bacteria. In the average human intestine, there are up to 100 trillion microorganisms, more than 10 times the number of human cells in the entire body! However, in the large intestine these bacteria are not harmful to your body. Instead, they are critical to the digestive process. The bacteria break down certain carbohydrates that your body can't break down with its enzymes. This bacterial action causes gas to be produced. Know what I mean? Bacteria in your large intestine also produce vitamin K which is used in blood clotting. Scientists are also learning that the bacteria in your gut play a big part in your immune system. For more about the bacteria in your intestines, click here. Animals that are herbivores have very different digestive systems that have parts to help them digest all of the fiber that they eat. In animals like cattle, deer, sheep, and giraffes, they have several stomach chambers and a longer digestive tract. Those chambers allow for much more bacterial fermentation and even the regurgitation of food to be re-chewed (chewing their cud) to be digested more thoroughly.
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Digestion What We Know The End The journey of your pizza slice has ended! From your mouth to the toilet, it has been on a long, 30-foot and up to 54-hour long trip through the digestive system. It has provided you with the nutrients you need to function, and a lesson on digestion. Image: http://clipart-library.com/pizza-cliparts.html
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How We Know Digestion
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Digestion How We Know Over the years, scientists have worked to unlock the once mysterious process of how humans digest food. Some of the approaches can even be used by you to discover what happens in the digestive tract!
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Digestion How We Know How do we learn about the different parts of the digestive system? When we dissect a dead animal, we can see the different parts along the tract that begins in the mouth and ends in the anus. The cells can be seen by making microscope slides. This is the stomach of a cow. The cow stomach is separated into four compartments, unlike a human stomach. This picture shows the stained cells found in the lining of the stomach, as seen under a microscope.
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Digestion How We Know How could we see where digestion begins? How would you find out if saliva has any digestion function? A quick way to find out is to compare a piece of steak (which has a lot of protein) and a cracker (which has a lot of starches). Place the meat in your mouth and do not chew it for about 2 minutes. What happens? You should discover that the steak keeps its shape. Next, place the cracker in your mouth without chewing it for about two minutes. You should notice that the cracker becomes soft in your mouth and you may even taste something sweet. This is because the cracker is composed of carbohydrates, which saliva is able to digest at least partly. The carbohydrates in the cracker begin to be broken down into individual glucose molecules by an enzyme in your saliva. This enzyme only breaks down carbohydrates, not proteins. Since the steak was mostly composed of proteins, it did not start breaking down like the cracker. This shows the locations of the glands that produce saliva.
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Digestion How We Know How do we know what goes on in our stomach? The stomach contains acids that turn most of your food into a liquid. Have you ever been sick and felt a burn in the back of your throat after vomiting? If you have, then you have experienced the power of the acids in your stomach. Stomach secretions also contain strong enzymes. The digestive functions of the stomach were discovered during an experiment performed by Doctor William Beaumont in 1822. In his experiment, Doctor Beaumont tested the digestive power of stomach fluids through a "fistula" or opening in the stomach (see the graphic on the right) that connected the stomach to the patient's skin. Doctor Beaumont tied food to a string, poked it through the fistula, and pulled it back out at varying times to see what had happened to the food. He observed that the food had changed, varying with the amount of time spent in the stomach and the nature of the food itself. One of the major things that was noticed by Doctor Beaumont is that proteins were especially degraded by the acids of the stomach. See more in the Storytime for this unit.
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Digestion How We Know How do we know what goes on in our stomach? Cont’d Today, similar experiments are done with cows. A fistula into the cow’s rumen, a compartment in the stomach, allows scientists to study the processes within. Also, healthy fluids from the rumen of the fistulated cows can be removed and inserted into the rumen of sick cows to help restore their rumen’s natural balance. A cow with a fistula. Photo from Berkeley Research: Jonas Løvaas Gjerstad
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Digestion How We Know How do we know the functions of the liver and gall bladder? The functions of the liver were identified by comparing the materials in the blood before and after the blood enters the liver. What scientists noticed was that the contents of the blood leaving the liver were much different from when the blood entered. Scientists also discovered that it did not matter if was right after a meal and the concentrations of carbohydrates, amino acids, and fats were high entering the liver or between meals, when the concentrations of carbohydrates, amino acids, and fats in the vessels entering the liver were low, their concentrations in the blood that left the liver were always the same. Thus, it seems that the liver is a nutrient storage organ that releases some of its stores as they are needed. We know that the liver is crucial for life. People die when the liver is destroyed, which often occurs in people who abuse alcohol (wine, beer, whiskey) for a long time. Click here or here for more information about alcohol and alcohol abuse. There is a virus that also destroys the liver ("infectious hepatitis") and that also can cause death. See also our Cells Are Us module in the Interacting with the Outside World unit for information on alcohol effects.
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Digestion How We Know How do we know the functions of the liver and gall bladder? Cont’d We have learned that the gall bladder's function of separating fat molecules from each other is not crucial. Often a person's gall bladder can become enlarged and inflamed, and the only treatment for this is to remove the gall bladder by surgery. People who have their gall bladders removed surgically seem to do just fine. Picture of the liver from a cow with the gallbladder circled in red.
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Digestion How We Know How do we know what the pancreas does? Similar to the process used to study the liver, the functions of the pancreas were discovered by comparing the contents of blood that enters the pancreas with that which leaves the pancreas. Diagram of the pancreas and its relationships with the bile duct and with blood vessels. The digestive juice duct empties into the small intestine. Scientists found that the pancreas secretes two hormones into blood: insulin - triggers cells to absorb sugar from the blood glucagon - triggers cells to secrete sugar into the blood Also, careful dissection reveals that two ducts connect the pancreas with the small intestine. One of the ducts comes from the gall bladder and contains a green fluid called bile. Collecting secretions from the other duct allowed scientists to discover that digestive enzymes were present to break down proteins, fats, and carbohydrates into smaller molecules. The pancreas produces those enzymes.
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Digestion How We Know How do we learn what happens in the small intestine? How did we discover that the main role of the small intestine is to absorb carbohydrates, amino acids, and fats? When the human body was first studied, scientists recognized that the weight of the food that entered the small intestine was much greater than the weight of wastes that came out. They concluded that the small intestine must be absorbing some of the contents of the food. Scientists showed that the contents in the large vein (the portal vein) that collects all the blood leaving the small intestine has a high amount of carbohydrates and amino acids. Why didn't they discover an increase in fats in the portal vein? Scientists knew that humans absorbed fats but they didn't know where. It was known that after eating a meal high in fat, like the fat in butter, there was a large increase in fatty acids in a large vein in the chest near the heart. So much fatty acid was present that when they drew blood from this vein from an animal that had eaten a high-fat meal, the blood had a white tinge! This discovery led scientists to figure out that fats were being absorbed through lymph vessels in the small intestine, since the lymphatic system empties into the bloodstream into this vein near the heart.
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Digestion How We Know How do we know about the functions of the large intestine? We know that the large intestine absorbs only water and salt, and the bacteria that live in the large intestine survive by digesting anything edible that was left undigested from the small intestine. How did scientists find this out? Before scientists had the luxury of sophisticated testing techniques, they knew that materials entering the large intestine were soft and fluid, but excreted wastes were drier and harder. From this, they concluded that the large intestine must be absorbing most of the fluid. This was confirmed when they examined the blood that leaves the large intestine. This blood had more water and salt than did the blood entering the large intestine. By culturing intestinal contents on growth medium in Petri dishes, scientists also discovered that the large intestine, but not the small intestine, has large numbers of bacteria. Researchers exactly determined the function of the bacteria by isolating them in specific cultures that contained different mixtures of carbohydrates, proteins, and fats. After incubating the bacteria, they tested each culture and found that not only can the bacteria break down certain foods that humans cannot (such as dietary fiber) but the bacteria also produce Vitamin K. Vitamin K is needed for normal blood clotting.
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William Beaumont (1785-1853) Storytime Digestion In 1822, an Army surgeon stationed at Fort Mackinac on the upper Michigan peninsula would change medical science. That surgeon, William Beaumont, was introduced to a 19-year-old gunshot victim, an employee of the American Fur Company. The patient, Alexis St. Martin, had multiple wounds, as you might expect from a shotgun. One of his wounds penetrated the stomach. Alexis agreed to let Beaumont experiment with him, allowing the surgeon to insert a six-inch tube into his stomach by way of an opening to the outside.
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William Beaumont (1785-1853) Digestion Storytime Medicine in the early nineteenth century was primitive. Doctors did not realize the importance of cleanliness. For the pain of rheumatism, Beaumont and fellow doctors prescribed opium, wood resin, and turpentine. Despite such uninformed and primitive medicine, Beaumont proudly claimed that none of his 200+ patients died. Beaumont was able to directly observe the release of stomach secretions in response to Alexis' eating different foods. He was also able to collect stomach contents, place them in glass tubes, and observe how much food was digested and the length of time it took for the food to break down. For centuries, many people believed that the stomach was hot and somehow "cooked" the food, acting as a fermenting vat or grinding mill. Beaumont, with the help of Alexis, proved that these superstitions were false.
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Becoming a Doctor Digestion Storytime William Beaumont had five sisters and three brothers, one of whom also became a physician. The children grew up on a farm in Connecticut. When William was 22, he tried to teach school. For a time, he was his town's schoolmaster as well as secretary for the local debating society. Beaumont decided that he wanted something different; he wanted to become a doctor. William's interest in medicine was likely stimulated by one of his school teachers, Silas Fuller, who later became a physician and served in the medical corps. In those days, there were not many medical schools and no standards for medical training. Some "doctors" practiced medicine with NO formal training. At age 26, William learned medicine by serving as an apprentice with two established physicians in Vermont. William received his license to practice surgery within a year.
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Life in the Army Digestion Storytime When the War of 1812 started, William joined the Army's medical corps and served in several battles, receiving a citation for bravery. When the war ended three years later, William re-entered civilian life and set up a practice in Plattsburgh, New York. Apparently unsatisfied with private practice, William re-joined the Army four years later and was stationed at Fort Mackinac, where he was to conduct his experiments on digestion. Even without war, life in the Army was pretty miserable in those days. The doctors sometimes had to sleep outdoors during the cold and wet Northern winters. "Hospitals" were commonly set up in barns or tents. William's pay was $30 per month. The hospital at Fort Mackinac had totally unacceptable conditions. In the winter, snow would actually blow into the building through cracks. In the summer, beds had to be moved around to keep patients from being rained on. Needless to say, medical supplies and equipment were limited. They often went for months without a thermometer!
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Life in the Army Cont’d Digestion Storytime Yet under these conditions, William conducted experiments on Alexis (his photo is on the right) that were the beginning of modern physiology, the science of bodily functions. Luckily, throughout the experiments, Alexis did not develop an infection under William's care. William could not get the stomach wound to heal, however. This was not all bad though, since it was the leakage of food that compelled William to put in a tube that could be closed off. And the tube, of course, gave William the chance to make direct observations on digestive processes. William was certainly not a scientist in the modern sense of the word. But he possessed one of the key characteristics of any good scientist: curiosity. He was tenacious, pursuing his experiments even when difficult and inconvenient.
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Life in the Army Cont’d Digestion Storytime While Alexis was recovering, William got him to stay around the hospital by hiring him as the family's live-in handyman. One of the more bizarre experiments that William conducted on Alexis included dangling a piece of food from a piece of string through the tube into the stomach. At hourly intervals, William pulled the string out and determined how much food had been digested. Different types of food (carbs, proteins, fats) were dangled through the tube in order to observe differences in the digestive rate. William performed similar experiments in glass containers, by removing stomach juices and putting different foods into the containers. Among Beaumont's observations, he discovered that gastric juice had to be warm in order to digest food. Cold gastric juice was ineffective. He also noticed how milk coagulated before digestion and how vegetables took longer to digest than other foods (due no doubt to their fiber content).
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Life in the Army Cont’d Digestion Storytime Beaumont did some of the first experiments involving the emotional/mental influence on digestion. Being angry, for example, was seen to impair digestion. All of these experiments were conducted over a span of several years with Alex St. Martin. During a tour of duty at Jefferson Barracks, near St. Louis, William and his wife became close personal friends with Lt. Robert E. Lee and his family. Lee later became a famous Confederate General during the Civil War.
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Final Days Digestion Storytime William finally left the Army in 1839, because they wanted him to go to Florida as part of the war against the Seminole Indians. William stayed on as a civilian doctor in St. Louis. He made about $10,000 per year, which was vastly more than he earned in the Army. In 1853, William slipped on an icy step in St. Louis, hit his head, and suffered a major hemorrhage. The trauma triggered an infection, and William died. Given the primitive Army hospitals that William had to work in, he would probably be surprised at the major medical complex of 70 buildings at Fort Bliss that has been named in his honor: William Beaumont Army Medical Center. The Center has a capacity of 600 beds and employs 1,500 military and 700 civilian personnel--a great change since the medical conditions of the 1800's! What became of Alex St. Martin? Actually, Alex lived some 58 years after he was shot. The hole in his stomach (called a "fistula") never healed. He complained from time to time of indigestion. Alex died of alcoholism and old age (he lived to be 86). To prevent anyone from examining his stomach wound or performing an autopsy, the family deliberately left Alex's body to decompose in the hot sun for four days. They buried the body in a deep, unmarked grave in a churchyard.
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References Digestion Storytime Beaumont, W. 1833. Experiments and Observations on the Gastric Juice and the Physiology of Digestion. F. P. Allen. Plattsburgh. Horsman, Reginald. 1996. Frontier Doctor: William Beaumont, America's First Great Medical Scientist. Univ. Missouri Press, Columbia, Missouri Nelson, R. B. III. 1990. Beaumont: America's First Physiologist. Grant House, Geneva, Illinois.
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Common Hazards Digestion
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Digestion Common Hazards Ulcers A peptic ulcer is a lesion in the mucus lining of the stomach or top part of the small intestine called the duodenum. The mucus protects the underlying cells in the wall of the stomach from the acidic digestive juices in the stomach. These juices contain a high concentration of hydrochloric acid (HCl), which is toxic to the cells due to its highly acidic nature. An ulcer can become serious if not treated because prolonged exposure to HCl will eventually cause bleeding at the exposed portion of the stomach or intestine wall. The most common symptom of an ulcer is a dull or burning pain in the belly that may come and go. It is felt most often when the stomach is empty. Source: healthdirect
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Digestion Common Hazards Ulcers: Causes The leading cause of ulcers is a bacterium. This bacterium, Helicobacter pylori (image below), was discovered in the early 1990's by a veterinarian who was studying ulcers in pigs. It resides in about 50% of people; these individuals have a much greater risk of developing ulcers because it damages the mucous coating that protects the lining of the stomach and duodenum. Together, the H. pylori and the stomach acid irritate the lining of the stomach or duodenum and cause the peptic ulcer. H. pylori can live in the body for years before symptoms start, but most people who have it will never get ulcers. It is unclear why only some people get ulcers after infection. Helicobacter pylori Source: University of Oregon
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Digestion Common Hazards Ulcers: Causes Cont’d Another cause of peptic ulcers is the long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, or stronger medications used in the treatment of arthritis or chronic inflammatory disease. These drugs block or reduce the amount of an enzyme that causes the production of a chemical that protects the stomach lining from acid and helps control bleeding. When NSAIDs block or reduce the amount of this enzyme in your body, they also increase your chance of developing a peptic ulcer. A rare disease, called Zollinger-Ellison syndrome, can also cause peptic ulcers. This disease causes tumors in the pancreas and duodenum. These tumors release a hormone that causes your stomach to produce large amounts of acid. The extra acid causes peptic ulcers to form in the duodenum.
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Digestion Common Hazards Ulcers: Treatment Treatment of ulcers includes the use of drugs to treat bacteria, reduce stomach acid, and protect the stomach lining. If the ulcer is caused by long-term use of NSAIDs, the patient should stop the use of those according to their doctor’s protocol. Antibiotics are used to treat bacteria. Medicines like PPIs (proton pump inhibitors) and histamine receptor blockers are used to reduce stomach acid. Protectants like bismuth subsalicylate, a component of Pepto-Bismol®, are used to coat and protect the mucus lining of the stomach. The most effective way to combat ulcers is a combination treatment of several types of medicines. To learn more about ulcers visit the following websites: https://www.niddk.nih.gov/health-information/digestive-diseases/peptic-ulcers-stomach-ulcers/symptoms-causes#NSAIDs https://medlineplus.gov/pepticulcer.html https://www.helico.com/whatishelicobacterpylori.html
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Digestion Common Hazards Food Poisoning Food poisoning, also called foodborne illness, is caused by eating contaminated food. Infectious organisms, including bacteria, viruses, and parasites or their toxins, are the most common causes of food poisoning. Many times, these organisms are transmitted by improper cooking and storage of foods, poor hygiene, or an unsafe food source. By cooking food well, using good hygiene, and watching what you eat, you can avoid consuming harmful organisms.
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Digestion Common Hazards Food Poisoning: Causes There are about twenty different species of bacteria and several species of protozoan parasites (protozoa: one-celled animals) that can cause food poisoning. Some common causes of food poisoning that you may have heard of include Salmonella and Campylobacter (commonly found on poultry and in contaminated eggs), E. coli and Listeria, (associated with contaminated raw fruits, vegetables, milk, and meat products), norovirus (commonly associated with “stomach flu,” the most common cause of foodborne illness, also transmitted from person to person), and certain protozoal parasites (found in undercooked fish, crabs, mollusks, meats, and vegetables). Symptoms of food poisoning are nausea, vomiting, abdominal cramps, fever, and diarrhea. Contrary to popular opinion, food poisoning does not always occur immediately after eating an infected food. Instead, it can be caused by food eaten several days prior to the onset of food poisoning. Sickness caused by food poisoning generally lasts from a few hours to several days.
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Digestion Common Hazards Food Poisoning: Treatment The best solution for food poisoning is to let the body treat the food poisoning on its own. Vomiting and diarrhea are the body's method of removing contaminated food. Through this process, the body may lose a great deal of water, making you dehydrated quickly. It is important that the body's fluid levels are replaced after vomiting and diarrhea by drinking liquids, including: Gatorade®, 7-UP®, apple juice, broth, bullion or Pedialyte®. These fluids can keep you from losing too much water as your body fights the food poisoning. All cases of restaurant food poisoning should be reported to your county public health department so that other people can be protected. However, it may not be easy to know when or where you ate the bad food. Different species of bacteria/protozoa can take longer before infecting an individual enough for symptoms to appear. It is essential to see a physician if diarrhea lasts longer than 24 hours, vomiting lasts longer than 12 hours, if there is blood in the stool, fever, excessive vomiting or diarrhea that cause severe muscle cramps, or an inability to keep down any fluids for 12 hours.
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Digestion Common Hazards Food Poisoning: Prevention Contamination of food can happen at any point of food production: growing, harvesting, processing, storing, shipping or preparing. Transferring harmful organisms from one surface to another is often the cause. This could include dirty cutting boards, dirty hands, and contaminated utensils. Raw, ready-to-eat foods, such as salads can be troublesome because they are not cooked. Proper cooking destroys the organisms that cause food poisoning. Ways to prevent food poisoning include washing your hands, cleaning tools used in preparing foods (including cutting boards, knives, sponges, and dishcloths), washing fruits and vegetables, cooking all food thoroughly, keeping foods very hot or very cold, refrigerating all leftovers within two hours of cooking, defrosting meat in the refrigerator or microwave, separating raw meats from other foods, and not buying canned goods that are in dented, bulging, or rusted cans. Wash hands before, during, and after preparing food. When you are washing your hands, use warm water and soap for twenty to thirty seconds. Always wash your hands after touching raw meat, fish, or poultry and after using the toilet. For more on food safety, click here.
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Digestion Common Hazards Food Poisoning: Prevention Cont’d To learn more about food poisoning, visit the following websites: http://kidshealth.org/kid/ill_injure/sick/food_poisoning.html http://www.nlm.nih.gov/medlineplus/ency/article/001652.htm http://www.webmd.com/food-recipes/food-poisoning/default.htm https://www.cdc.gov/foodsafety/prevention.html
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Activities Digestion
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Click to download an activity Digestion Activities Student Activity Sheet #1- The Story of Digestion Student Activity Sheet #2- Let’s Eat! Student Activity Sheet #3- Digestive System Diagram
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Self-Study Game Digestion
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Click to play a game Digestion Self-Study Game Quizizz
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Post-Test Digestion Click below to take the post-test for this unit! Google assessment
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Glossary Digestion A-Di amino acids - molecules that contain an amino group (NH2) and a carboxyl group (HCO2) with a subunit coming off of the alpha carbon (the carbon between the amino and carboxyl group). There are twenty natural amino acids and they serve as the building blocks of proteins. Return to Introduction | Return to Why It Matters | Return to What We Know bacteria – single-celled microorganisms that can be free living or live in/on other organisms. Return to How We Know carbohydrates - compounds composed of only carbon, oxygen, and hydrogen. Carbohydrates consist of starches and sugars, such as glucose. Glucose is necessary for production of energy, especially in the brain. Return to Introduction | Return to Why It Matters bile - a greenish-yellow fluid excreted from the liver into the small intestine, near the attachment to the stomach. This fluid helps emulsify or dissolve fats so the body can absorb them. Bile consists of cholesterol, bile salts, and worn out red blood cells. An imbalance in these chemicals leads to gallstones. Return to Why It Matters diabetes - a chronic condition of having abnormally high levels of sugar (glucose) in the blood. This disease is usually caused by a deficiency in insulin, an enzyme that lowers the blood's glucose level. The excess glucose in the blood is excreted through urine. The body needs this glucose to make energy. For example, the brain only uses glucose to make energy. Without enough glucose, the brain will stop functioning. Return to Why It Matters | Return to What We Know
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Glossary Digestion Du-Le duodenum - the first part of the small intestine. During digestion, bile is released from the gallbladder into the duodenum. Return to What We Know enzyme - a protein that speeds up chemical reactions in living organisms. Enzymes lower the energy necessary to turn a set of reactants into other products. Without enzymes, we could not exist. Return to Why It Matters fermentation - the breakdown of an energy-rich compound in anaerobic (without oxygen) conditions. Bacteria break down nutrients through fermentation, but the human body also uses fermentation. Vigorously contracting muscle cells and red blood cells both use fermentation to produce energy. Return to What We Know fiber - dietary fiber, or roughage, is a type of carbohydrate that cannot be digested by humans. Return to What We Know glucagon - a hormone released by alpha cells in the pancreas. Glucagon is released when blood-sugar levels begin to drop below normal (like between meals) and signals cells to release glucose into the bloodstream. Return to What We Know | Return to How We Know insulin - a hormone released by beta cells in the pancreas. Insulin is released when blood-sugar levels are higher than normal (like after eating) and signal cells to take up glucose from the bloodstream. Return to Why It Matters | Return to What We Know | Return to How We Know lesion - an abnormal change in any tissue or organ due to disease or injury. The lesion caused by ulcers involved a hole in the tissue. Return to Common Hazards
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Glossary Digestion lipids - Lipids are also known as fats, but they include compounds of many different kinds. Chemically, these compounds are built on a backbone of glycerol, which was a three-carbon chain. Each carbon, in turn, bonds via an oxygen molecule to so-called fatty acids. Fatty acids have an acid group (COOH) at one end that is attached to a chain of carbons. Lipids differ mainly in the nature of the fatty acid chains. Return to Introduction | Return to Why It Matters lymphatic system - a body system composed of a network of vessels and nodes that carry and filter a fluid called lymph. This system is part of both the immune and cardiovascular systems. Return to How We Know minerals - elements found in the earth and in foods that are necessary for normal bodily development and function. Essential minerals include calcium, chloride, chromium, copper, fluoride, iodine, iron, magnesium, manganese, molybdenum, phosphorus, potassium, selenium, sodium, and zinc. Return to Why It Matters nutrients - substances that provide nourishment and are necessary for growth and maintenance of life. There are seven classes of nutrients: carbohydrates, lipids (fats), proteins, minerals, vitamins, and water. Return to Introduction | Return to Why It Matters portal vein - a large vein that carries nutrients, such as carbohydrates and amino acids, from the stomach and small intestine to the liver for detoxification. Return to How We Know Li-Po
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Glossary Digestion proteins - molecules made of long strings of repeating units, called amino acids. Amino acids have carbon, hydrogen, oxygen, and nitrogen in them. When they attach to each other in long strings, they coil. The coiled folds back on itself to form an irregularly shaped clump. Return to Why It Matters secrete - to produce and release a substance from a cell/organ. Insulin is secreted by beta cells in the pancreas. Return to Why It Matters toxin - a poisonous agent produced by certain animals, plants, and bacteria. A toxin usually has a large molecular weight and is antigenic. Return to What We Know vitamins - organic molecules that are essential to our bodies but only in very small quantities. Vitamins do not, in themselves, provide energy, but they help our bodies carry out metabolic processes to make energy. Return to Why It Matters Pr-V