The Digestive System: Structures, Functions, and Disorders PDF

Overview of Stuctures Mouth (or/o, stomat/o)= Begins the preparation of food for digestion Teeth (odont/i)= Used for biting tearing, and chewing in mechanical digestion. Pharynx (pharyng/o)= Transports food from the mouth to the esophagus Esophagus (esophag/o) Transports food from the pharynx to the...

Overview of Stuctures Mouth (or/o, stomat/o)= Begins the preparation of food for digestion Teeth (odont/i)= Used for biting tearing, and chewing in mechanical digestion. Pharynx (pharyng/o)= Transports food from the mouth to the esophagus Esophagus (esophag/o) Transports food from the pharynx to the stomach Stomach (gastr/o)= Breaks down food and mixes it with gastric juices. Small Intestine (enter/o)= Mixes chyme coming from the stomach with digestive juices to complete the digestion and absorption of most nutrients. Large Intestine (col/o, colon/o)= Absorbs excess water and prepares solid waste for elimination. Rectum and Anus (an/o, proct/o, rect/o) control the excretion of solid waste. Liver (hepat/o)= secretes bile and enzymes to aid in the digestion of fats. Gallbladder (cholecyst/o)= stores bile and releases it into the small intestine as needed. Pancreas (pancreatic/o)= Secretes digestive juices and enzymes into the small intestine as needed. Vocabulary Related to the Digestive System an/o anus, ring chol/e bile, gall -emesis vomiting -lithiasis presence of stones -pepsia digest, digestion -phagia eating, swallowing sigmoid/o sigmoid colon Structures and Functions of the Digestive System The digestive system consists primarily of the gastrointestinal tract, which is also known as the GI tract. These organs work in cooperation with accessory organs. The upper GI tract consists of the mouth, pharynx, esophagus, and stomach. This transports food from entry into the body until digestion begins in the stomach. The lower GI tract, which is sometimes referred to as the bowels, is made up of the small and large intestines plus the rectum and anus. Here digestion is completed and waste material is prepared for expulsion from the body The accessory organs of the digestive system are the liver, gallbladder, and pancreas. The Oral Cavity The major structure of the oral cavity, aka the mouth, are the lips, hard and soft palates, salivary glands, tongue, teeth, and periodontium. The Lips The lips aka the labia, surround the opening to the oral cavity. During eating, the lips, tongue, and cheeks hold the food in the mouth. The lips also have important roles in breathing, speaking, and the expression of emotions. The Palate The palate, which forms the roof of the mouth, consists of three major parts. The hard palate is the anterior portion of the palate. This area is covered with specialized mucous membrane. The soft palate is the flexible posterior portion of the palate. During swallowing, it has the important tole of closing off the nasal passage to prevent food and liquid from moving upward into the nasal cavity.  The uvula is the third part, and it hangs from the free edge of the soft palate. During swallowing, it moves upward with the soft palate. It also plays an important role in snoring and in the formation of some speech sounds. The Tongue The tongue is very strong, flexible, and muscular. The posterior portion of the tongue is attached. The anterior end of the tongue moves freely and is flexible. It is the structure of the tongue that makes it so important for chewing, speaking, and swallowing. The upper surface of the tongue is the dorsum. This surface has a tough protective covering and in some areas, small bumps known as papillae. These papillae contain taste buds, which are the sensory receptors for the sense of taste. The sublingual surface of the tongue and the tissues that lie under the tongue are covered with delicate highly vascular tissues. The presence of this rich blood supply under the tongue makes it suitable for administering certain medications sublingually by placing them under the tongue, where they are quickly absorbed into the bloodstream. The lingual frenum is a band of tissue that attaches the tongue to the floor of the mouth. This frenum limits the motion of the tongue. Soft Tissues of the Oral Cavity The term periodontium describes the structures that surround, support, and are attached to the teeth. This consists of the bone of the dental arches and the soft tissues that surround and support the teeth. The gingiva aka masticatory mucosa or the gums, is the specialized mucous membrane that covers the bone of the dental arches and surrounds the neck of the teeth. The sulcus is an area of space between a tooth and the surrounding gingiva. A buildup of food debris and bacteria in the sulcus can lead to infection. The Dental Arches The dental arches are the bony structures of the oral cavity. These arches hold the teeth firmly in position to facilitate chewing and speaking. The maxillary arch is commonly known as the upper jaw and consists of bones of the lower surface of the skull. This arch does not move. The mandíbulas arch, commonly known as the lower jaw, is a separate bone and is the only movable component of the joint. The temporomandibular joint is formed at the back of the mouth where the maxillary and mandíbulas arches come together. The Teeth The term dentition refers to the natural teeth arranged in the upper and lowers jaws. Human dentition consists of four types of teeth Incisors and Canines (aka cuspids). These teeth are used for biting and tearing. Premolars, which are also known as bicuspids, and molars. These teeth are used for chewing and grinding. Primary and permanent Dentition The primary dentition is also known as the baby teeth. These 20 teeth erupt during early childhood, are normally lost in late childhood, and are replaced by the permanent teeth. The primary dentition consists of eigh incisors, four canines, and eight molars but no premolars. The permanent dentition consists of 32 teeth designed to last a lifetime. Of these teeth, 20  replace primary teeth and 12 erupt at the back of the mouth. The permanent dentition includes 8 incisors, 4 canines, 8 premolars, and 12 molars. The third molars, which are the last to erupt, are also known as wisdom teeth. The term occlusion, as use in dentistry, describes any contact between the chewing surfaces of the upper and lower teeth. Stuctures and Tissues of the Teeth The crown is the portion of a tooth that is visible in the mouth. It is covered with enamel, which is the hardest substance in the body. The roots of the tooth hold it securely in place within the dental arch. The roots are protected by cementum. Thi substance is hard, but it is not as strong as enamel. The cervix, aka the neck of the tooth, is where the crown and root meet. Dentin makes up the bulk of the tooth. The portion that is above the gum line is covered with enamel. The root area is covered with cementum. The pulp cavity is the area within the crown and root of the tooth that is surrounded by the dentin to protect the delicate pulp of the tooth. In the roots, the pulp continues in the space known as the root canals. The pulp itself consists of a rich supply of blood vessels and nerves that provide nutrients and innervation to the tooth. Saliva and Salivary Glands Saliva is a colorless liquid that maintains the moisture in the mouth. It helps maintain the health of the teeth, and it begins the digestive process by lubricating food during chewing and swallowing. Saliva also contains the digestive enzyme amylase and is the first step in chemical digestion. The three pairs of salivary glands secrete saliva that is carried bu ducts into the mouth. the parotid glands are located on the face, slightly in front of each ear. The ducts for these glands are on the inside of the cheek near the upper molars. The sublingual glands and their ducts are located on the floor of the mouth under the tongue. The submandibular glands and their ducts are located on the floor of the mouth near the mandible. The Pharynx The pharynx is the common passage way for both respiratory and digestion. The pharynx plays an important role in deglutition, which is commonly known as swallowing. The epiglottis is a lid-like structure that closes off the entrance to the trachea to prevent food and liquids from moving from the pharynx during swallowing. The Esophagus The esophagus is the muscular tube through which ingested food passes from the pharynx to the stomach. The lower esophageal sphincter, aka cardiac sphincter, is a muscular ring between the esophagus and stomach. During swallowing, it relaxes to allow food to enter the stomach. The sphincter normally opens to allow the flow of food into the stomach and closes to prevent the stomach contents from regurgitating into the esophagus. The Stomach The stomach is a sac-like organ composed of fundus (upper, rounded part), body, and antrum (lower part). Rugae are the folds in the mucosa lining the stomach. These folds allow the stomach to increase  and decrease in size. Glands located within these folds produce gastric juices. Gastric juices made up of enzymes and hydrochloric acid aid in the beginning of food digestion. Mucus produced by glands in the stomach creates a protective coating on the lining of the stomach. The pyloric sphincter is the ring-like muscle at the base of the stomach that controls the flow of partially digested food from the stomach to the duodenum of the small intestine. The Small Intestine The small intestine extends from the pyloric sphincter to the first part of the large intestine. This coiled organ is up to 20 feet in length and consists of three sections where food is digested and nutrients are absorbed into the bloodstream. 1. The duodenum is the first portion of the small intestine. The duodenum extends from the pylorus of the stomach to the jejunum. 2. The jejunum, which is the middle portion of the small intestine, extends from the duodenum to the ileum. 3. The ileum, which is the last and longest portion of the small intestine, extends from the jejunum to the cecum of the large intestine. The Large Intestine The large intestine extends from the end of the small intestine to the anus. It is about twice as wide as the small intestine; however, it is only one-fourth as long. It is here that the waste products of digestion are processed in preparation for excretion through the anus. The major parts of the large intestine are the cecum, colon, rectum, and anus. The Cecum The cecum is a pouch that lies on the right side of the abdomen. It extends from the end of the ileum to the beginning of the colon. The ileocecal sphincter is the ring-like muscle that controls the flow from the ileum of the small intestine into the cecum of the large intestine. The vermiform appendix, commonly called the appendix, hangs from the lower portion of the cecum. The term vermiform refers to a worm-like shape. The Colon The colon, which is the longest part of the large intestine, is subdivided into four parts. The ascending colon travels upward from the cecum to the undersurface of the liver. The transverse colon passes horizontally across the abdominal cavity from right to left toward the spleen. The descending colon travels down the left side of the abdominal cavity to the sigmoid colon. The sigmoid colon is an S-shaped structure that continues from the descending colon above and joins the rectum below. Sigmoid means curved like the letter S. The Rectum and Anus The rectum is the widest division of the large intestine. It makes up the last 4 inches of the large intestine and ends at the anus. The anus is the lower opening of the digestive tract. The flow of waste through the anus is controlled by the internal anal sphincter and the external anal sphincter. The term anorectal refers to the anus and rectum as a single unit.. Accessory Digesive Organs The accessory organs of the digestive system are so named because they plat a key role in the digestive process but are not part of the gastrointestinal tract. The accessory digestive organs are the liver, gallbladder, and pancreas. The Liver The liver is the largest organ in the body. It has several important functions relating to removing toxins from the blood and turning food into the fuel and nutrients the body needs. The liver removes excess glucose, which is commonly known as blood sugar, from the bloodstream and stores it as glycogen. Glycogen is a form of glucose that is stored in the liver and muscles. when the blood sugar level is low, the liver converts glycogen back into glucose and releases it for use by the body. Bile, which aids in the digestion of fats, is a digestive juice secreted by the liver that is necessary for the digestion of fat. Bile travels from the liver to the gallbladder, where it is concentrated and stored. Bilirubin is pigment formed in the liver by the breakdown of hemoglobin and excreted in bile, giving it a yellow to green color. Excessive amounts of bilirubin in the body can lead to jaundice and other diseases. The Biliary Tree The biliary provides the channels through which bile is transported from the liver to the small intestine. Biliary means pertaining to bile. Small ducts in the liver join together like branches to form the biliary tree. the trunk, which is just outside the liver, is known as the common hepatic duct. The bile travels from the liver through the common hepatic ducts to the gallbladder where it enters and exits through the narrow cystic duct. The cystic ducts leaving th gallbladder rejoins the common hepatic ducts to form the common bile duct. The common bile duct joins the pancreatic duct, and together they enter the duodenum of the small intestine. The Gallbladder The gallbladder is a pear-shaped organ about the size of an egg located under the liver. it stores and concentrates bile for later use. When bile is needed, the gallbladder contracts, forcing the bile out through the biliary tree. The term cholecystic means pertaining to the gallbladder. The Pancreas The pancreas is a soft, 6-inch-long, oblong gland that is located behind the stomach. This gland has important roles in both the digestive and endocrine systems. The pancreas produces and secretes pancreatic juices that aid in digestion and contain digestive enzymes and sodium bicarbonate to help neutralize the stomach acids. The pancreatic juices leave the pancreas through the pancreatic duct that joins the common bile duct just before the entrance into the duodenum. Digestion Digestion is the process by which complex foods are broken down into nutrients in a form the body can use. Digestive enzymes are responsible for the chemical changes that break foods down into simpler forms of nutrients for use by the body. A nutrient is a substance, usually from food, that is necessary for the body to function. the primary nutrients, called macronutrients, which provide the body with calories are  carbohydrates, fats, and proteins. A calorie is a unit of energy. Vitamins and minerals are essential micronutrients, which means they are required only in small amounts. Metabolism The term metabolism includes all of the processes involved in the body’s use of nutrients. It consists of two parts: Anabolism is the building up of body cells or substances from nutrients. Catabolism is the breaking down of body cells or substances, releasing energy and carbon dioxide. Absorption Absorption is the process by which completely digested nutrients are transported to the cells throughout the body. The mucosa that lines the small intestine is covered with finger-like projections called villi. Each villus contains blood vessels and lacteals. The blood vessels absorb nutrients directly from the digestive system into the bloodstream for delivery to the cells of the body. The lacteals, which are specialized structures of the lymphatic system, absorb fats and fat- soluble vitamins that cannot be transported directly by the bloodstream. Instead they absorb these nutrients and transport them via lymphatic vessels. As these nutrients are being transported, they are filtered by the lymph nodes in preparation for their delivery to the bloodstream. The Role of the Mouth, Salivary Glands, and Esophagus Mastication (chewing) breaks food down into smaller pieces, mixes it with saliva, and prepares it to be swallowed. A bolus is a mass of food that has been chewed and is ready to be swallowed. During swallowing, food travels from the mouth into the pharynx and on into the esophagus. In the esophagus, food moves downward through the action of gravity and peristalsis. Peristalsis is a series of wave-like contractions of the smooth muscles in a single direction that moves the food forward into the digestive system. The Role of the Stomach The gastric juices of the stomach contain hydrochloric acid and digestive enzymes to continue the breakdown of food. Few nutrients enter the bloodstream through the walls of the stomach. The churning action of the stomach works with the gastric juices by converting the food into chyme. Chyme (KYM) is the semi fluid mass of partly digested food that passes out of the stomach, through the pyloric sphincter, and into the small intestine. The Role of the Small Intestine The conversion of food into usable nutrients is completed as the chyme is moved through the small intestine by peristaltic action. In the duodenum, chyme is mixed with pancreatic juice and bile. The bile breaks apart large fat globules so that enzymes in the pancreatic juices can digest the fats. This action is called Emulsification and must be completed before the nutrients can be absorbed into the body. the jejunum secretes large amounts of digestive enzymes and continues the process of digestion. The primary function of the ileum is to absorb nutrients from the digested food. The Role of the Large Intestine The role of the entire large intestine is to receive the waste products of digestion and store them until they are eliminated from the body.  Food waste enters the large intestine where excess water is reabsorbed into the body through the walls of the large intestine, helping maintain the body’s fluid balance. The remaining waste forms into feces. Feces are expelled through the rectum and anus. Defecation (bowl movement) is the evacuation or emptying of the large intestine. The large intestine contains gut microbiota, which help break down organic waste material. This process produces gas. Gut microbiota refers to the billions of bacteria present in the large intestine to protect against infection and help maintain the immune system. Studies are ongoing that show a link between gut microbiota and various physical and mental health diseases. Borborygmus is he rumbling noise caused by the movement of gas in the intestine. Flatulence is the passage of gas also called flatus out of the body through the rectum. Medical Specialities Related to the Digestive System Bariatrics is the branch of medicine concerned with the prevention and management of obesity and associated diseases. A dentist holds a doctor of dental surgery (DDS) or doctor of medical dentistry (DMD) degree and specialized in diagnosing and treating diseases and disorders of teeth and tissues of the oral cavity. A prosthodontist is a dentist who specialized in the restoration and replacement of teeth. A gastroenterologist is a physician who specialized in diagnosing and treating diseases and disorders of the stomach and intestines. An oral or maxillofacial surgeon specializes in surgery of the face and jaws to correct deformities, treat diseases, and repair injuries. An orthodontist is a dental specialist who prevent or corrects malocclusion of the teeth and related facial structures. A periodontist is a dental specialist who prevents or treats disorders of the tissues surrounding the teeth. A proctologist is a physician who specializes in disorders of the colon, rectum, and anus. A registered dietitian or registered dietitian nutritionist is a specialist in food and nutrition who practices medical nutrition therapy and counsels patients on improving their dietary intake. Pathology of the Digestive System Tissues of the Oral Cavity Canker sores, also known as aphthous ulcers, are gray-white pits with a red boarder in the soft tissues lining the mouth. Although the exact cause is unknown, the appearance of these common sores is associated with stress, certain foods, or fever. An ulcer is an open lesion of the skin or mucous membrane resulting in tissue loss around the edges. Cheilitis (cheilosis), is inflammation of the lips characterized by crack-like sores at the corners of the mouth. Cold sores, also known as herpes labialis or fever blisters, are blister-like sores on the lips adjacent facial tissue that are caused by the oral herpes simplex virus type 1 (HSV-1). Most adults have been infected by this extremely common virus, and in some, it becomes reactivated periodically, causing cold sores. Leukoplakia is an abnormal white, usually benign lesion (sore) that develops on the tongue or the inside of the cheek. These lesions develop in response to chronic irritation in the mouth such as smoking, chewing tobacco, or constan rubbing against a broken tooth. Occasionally, leukoplakia patches occur on the genitals, in the digestive systems, or in the urinary tract. Stomatitis is an inflammation of the mucosa of the mouth. Oral thrush is a fungal infection in the mouth caused by Candida albicans. The symptoms are  crazy white lesions on the tongue or inner cheeks. This condition occurs most often in infants, older adults with weakened immune systems, or individuals who have been taking antibiotics. The term trismus (lockjaw), describes any restriction to the opening of the mouth caused by trauma, surgery, or radiation associated with the treatment of oral cancer. this condition causes difficulty in speaking and affects the patient’s nutrition due to impaired ability to chew and swallow. Xerostomia (dry mouth) is the lack of adequate saliva due to diminished secretions by the salivary glands (xer/o means dry). This condition can be due to medications or radiation of the salivary glands, and can cause discomfort, difficulty in swallowing, changes in the taste of food, and dental decay. Cleft Lip and Cleft Palate A cleft lip is a birth defect in which there is a deep groove of the lip running upward to the nose as a result of the failure of this portion of the lip to close during prenatal development. A cleft palate is the failure of the palate to close during the early development of the fetus. This opening can involve the upper lip, hard palate, and/or soft palate. If not corrected, this opening between the nose and mouth makes it difficult for the child to eat and speak. Cleft lip and cleft palate can occur singly or together and usually can be corrected surgically. Dental Disease and Conditions Bruxism is the involuntary grinding of the teeth that usually occurs during sleep and is associated with tension or stress. It can also occur habitually during the day. Bruxism wears away tooth structure, damages periodontal tissue, and injures the temporomandibular joint. Dental caries , also known as tooth decay or cavities, are an infectious disease caused by bacteria that destroy the enamel and dentin of the tooth. If the decay process is not arrested, the pulp can be exposed and become infected. Dental plaque, which is a major cause of dental caries and periodontal disease, forms as soft deposits in sheltered areas near the gums and between the teeth. Dental plaque consists of bacteria and bacterial by-products. I Edentulous means without teeth. This terms describes the situation after the natural permanent teeth have been lost. Halitosis (bad breath) is an unpleasant odor coming from the mouth that can be caused by dental diseases or reporatory or gastric disorders (halit means breath) Malocclusion is any deviation from the normal positioning of the upper teeth against the lower teeth. In an overbite there is an excessive overlap of the upper and lower teeth, and in an underbite the lower teeth are in front of the upper teeth. Periodontal Disease Periodontal disease (periodontitis) is an inflammation of the tissue that surround and support the teeth. This progressive disease is classified according to the degree of tissue involvement. In severe cases, the gums and bone surrounding the teeth are involved. Dental calculus (tartar) is dental plaque that had calcified on the teeth. These deposits irritate the surrounding tissues and cause increasingly serious periodontal diseases. The term calculus is also used to describe hard deposits, such as gallstones or kidney stones, that form in other parts of the body. Gum recession is the shrinking of gingival tissue often associated with aging. Gingivitis is the earliest stage of periodontal disease , and the inflammation affects only the gums. Acute necrotizing ulcerative gingivitis (ANUG) aka trench mouth, is caused by the abnormal growth of bacteria in the mouth. As this condition progresses, the inflammation, bleeding, deep  ulceration, and death of gum tissue become more severe. Necrotizing means causing ongoing tissue death. The Esophhagus Dysphagia is difficulty in swallowing. Eosinophilic esophagitis is a chronic immune system disease in which a type of white blood cell called eosinophil builds up in the esophagus, usually as the result of an allergy to certain foods. The resulting inflammation can make it difficult to swallow. this disease appears to be increasingly common in children and adults. Gastroesophageal reflux disease (GERD) is the upward flow of acid from the stomach into the esophagus. When this occurs, the stomach acid irritates and damages the delicate lining of the esophagus. Barrett’s esophagus is a condition that occurs when the cells in the epithelial tissue of the esophagus are damaged by chronic acid exposure. Some patients with chronic GERD develop this complication, which slightly increases the risk of esophageal cancer. A stricture of the esophagus resulting from scar tissue or other damage can cause swallowing difficulties. A stricture is an abnormal narrowing of a bodily passage. Pyrosis (heartburn) is a burning sensation in the chest caused by the return of acidic stomach contents into the esophagus. Esophageal varices are enlarged and swollen veins at the lower end of the esophagus. This condition, which is associated with serious liver disease, can cause severe bleeding if one of these veins ruptures. A hiatal hernia is an anatomical abnormality in which a portion of the stomach protrudes upward into the chest, through an opening in the diaphragm (hiat means opening). A hernia is the protrusion of a part or structure through the tissues that normally contain it. This condition can cause GERD or pyrosis. The Stomach Gastritis is a common inflammation of the stomach lining that can cause nausea and vomiting. In chronic cases it is often caused by the bacterium Helicobacter pylori. Gastroenteritis is an inflammation of the mucous membrane lining the stomach and intestines. Gastroparesis is a condition in which gastric motility slows down, causing delayed gastric emptying. Peptic Ulcers Peptic ulcers disease is characterized by sores that affect the mucous membranes of the digestive system. Peptic ulcers are caused by the bacterium Helicobacter pylori or by medications, such as aspiri, that irritate the mucous membranes. Gastric ulcers are peptic ulcers that occur in the stomach Duodenal ulcers are peptic ulcers that occur in the upper part of the small intestine. A perforated ulcer is a complication of a peptic ulcer in which the ulcer erodes through the entire thickness of the organ wall. Nutritional Disorders Anorexia is the loss of appetite for food, especially when caused by disease (-orexia means appetite). Cachexia is a condition of physical wasting away due to the loss of weight and muscle mass that occurs in patients with disease such as advanced cancer or AIDS. Although these patients might be eating enough food, their bodies are unable to absorb enough nutrients. Dehydration is a condition is which fluid loss exceeds fluid intake and disrupts the body’s normal  electrolyte balance. Failure to thrive (FTT) is when an infant or child does not grow as expected due to any number of reasons including malabsorption or malnutrition. Malabsorption is a condition in which the small intestine cannot absorb nutrients from food that passes through it. Malnutrition is a lack of proper food nutrients in the body due to a shortage of food, poor eating habits, or the inability of the body to digest, absorb, and distribute these nutrients. Overweight and Obesity Overweight and obesity are weight classifications based on BMI that are higher than a healthy weight for someone based on their height, gender, and age. The body mass index is a ration of weight in kilograms divided by height in meters squared. Severe obesity is the condition of having a body mass index value grater than 40. BMI can indicate a high level of body fa but is not a measure of body fat. Obesity is frequently present as a comorbidity with condition such as metabolic syndrome, hypertension, and diabetes. Comorbidity describes the presence of more than one disease or health condition in an individual at a given time. Indigestion and Vomiting Aerophagia is the excessive swallowing of air while eating or drinking and is a common cause of gas in the stomach. Dyspepsia (indigestion), is pain or discomfort during the digestion process. Functional dyspepsia is recurring indigestion with no known cause. Emesis (vomiting) is the reflex ejection of the stomach contents outward through the mouth. Eructation is the act of belching or raising gas orally from the stomach. Hematemesis is the vomiting of coagulated blood. The substance that is vomited often resembles coffee grounds. Hyperemesis is extreme, persistent vomiting that can cause dehydration. During the early stages of pregnancy, this is known as morning sickness. Nausea is the urge to vomit Regurgitation is the return of swallowed food into the mouth Intestinal Disorders Celiac disease is an autoimmune disorder characterized by a severe reaction to ingesting gluten. Gluten is a type of protein found in grains such as wheat, barley, and rye. This common disorder damages the villi of the small intestine and can cause malabsorption. Gluten intolerance, (non-celiac gluten sensitivity) is a response to gluten involving digestive distress but not causing the intestinal tissue damage of celiac disease. A food allergy is an immune system reaction that occurs after eating a certain food. Lactose intolerance is the inability to digest dairy products due to the absence of the enzyme lactase, which is needed to process the sugar lactose found in milk and some other dairy products. Lactose intolerance is particularly common among African Americans and East Asians. Small intestinal bacterial overgrowth (SIBO) can cause gastrointestinal upset such as gas, bloating, diarrhea, constipation, and nausea. Colorectal carcinoma (colon cancer) often first manifests itself in polyps in the colon A polyp is a mushroom-like growth from the surface of a mucous membrane. Not lol polyps are malignant. Diversticulosis is the chronic presence of an abnormal number of diverticula, or sacs, formed in weak spots of the colon wall. Diverticulosis, which often has no symptoms, is more common in  people over the age of 50. A diverticulum is a small pouch, or sac, found in the lining or wall of a tubular organ such as the colon. Diverticulitis is the inflammation or infection of one or more diverticulum in the colon. Symptoms of this condition can include sudden abdominal pain, cramping, and nausea. Enteritis is an inflammation of the small intestine caused by ingesting substances contaminated with viral or bacterial pathogens which causes diarrhea. Ischemic colitis occurs when part of the large intestine is partially or completely deprived of blood. If this lack of blood persists, it can lead to inflammation and permanent damage of the affected area. Ileus Ileus is the partial or complete blockage of the small or large intestine. This condition is also known as paralytic ileus, and it is caused by the stopping of the normal peristalsis of this area of the intestine. Symptoms of ileus can include severe pain, cramping, abdominal distensión, vomiting, and the inability to pass gas or stools Postoperative ileus is a temporary impairment (stoppage) or bowl action that is considered to be a normal response to abdominal surgery. It is often present for 24 to 72 hours, depending on which part of the digestive system was treated. Irritable bowl syndrome Irritable bowl syndrome (IBS) is a common condition of unknown cause with symptoms that can include intermittent cramping and abdominal pain, accompanied by constipation of diarrhea. This condition, which is usually aggravated by stress and by eating certain foods, is not believed to be caused by pathogens. Inflammatory Bowl Diseases Inflammatory bowl disease (IBD) is the general name for diseases that cause inflammation and swelling in the intestines. The two most common inflammatory bowel disease are ulcerative colitis and Crohn’s disease. These conditions are becoming more common and can increase risk of colorectal cancer. These conditions are grouped together because both are chronic and incurable and can affect the large and small intestines. They also have similar symptoms, which can include abdominal pain, weight loss, fatigue, fever, rectal bleeding, enteropathic arthritis, and diarrhea. These conditions tend to occur at internals of active disease known as flares alternating with periods of remission. Ulcerative Colitis Ulcerative colitis is a chronic condition of unknown cause in which repeated episodes of inflammation in the rectum and large intestine cause ulcers (lesions in the mucous membrane) and irritation. Ulcerative colitis usually starts in the rectum and progresses upward to the lower part of the colon; however, it can affect the entire large intestine. Ulcerative colitis affects only the innermost lining and not the deep tissues of the colon. Crohn’s Disease Crohn’s disease is a chronic autoimmune disorder that can occur anywhere in the digestive tract; however, it is most often found in the ileum and in the colon. In contrast to ulcerative colitis, Crohn’s disease generally penetrates every layer of tissue in the affected area. This can res tilt in scarring and thickening of the walls of the affected structures. The most common complication of Crohn’s disease is blockage of the intestine due to swelling and scarring Intestinal Obstructions An intestinal obstruction is the partial or complete blockage of the small or large intestine cause by a physical obstruction. This blockage can result from many causes such as scar tissue, a tumor, or the ingestion and buildup of indigestible materials, called a bezoar. Intestinal adhesions abnormally hold together parts of the intestine that should be separate. This condition, which is caused by inflammation or trauma, can lead to intestinal obstruction. In a strangulating obstruction, the blood flow to a segment of the intestine is blocked. This can lead to gangrene or perforation. Gangrene is tissue death that is associated with a loss of normal circulation. As used here, perforation describes a hole through the wall of a structure. Volvulus is the twisting of the intestine on itself, causing an obstruction. Volvulus is a Latin word meaning rolled up or twisted. This condition can cause necrosis of the affected segment of the bowel. An inguinal hernia is the protrusion of a small loop of bowel through a weak place in the lower abdominal wall or groin. This condition can be caused by obesity, pregnancy, heavy lifting, or straining to pass a stool. A strangulated hernia occurs when a portion of the intestine is constricted inside the hernia, causin ischemia (insufficient oxygen) in this tissue by cutting off its blood supply. Infectious Disease of the Intestines Infectious diseases of the intestines can be transmitted through contaminated food and water or through poor sanitation practiced. The more common of these infectious disease include the following: Clostridium difficile is a common bacterial infection, typically following the use of antibiotics that wipe out competing bacteria. This disease causes diarrhea and can lead to inflammation of the colon. Infection control measures such as handwashing and wearing gloves can help prevent its spread. Dysentery, which is a bacterial infection, occurs most frequently in tropical countries where it is spread through food or water contaminated by human feces. E. Coli which is caused by the bacterium Escherichia coli is transmitted through contaminated foods that have not been adequately cooked. Salmonellosis (salmonella) is transmitted by feces, either through direct contact with animals, or by eating contaminated raw or undercooked meat, poultry, seafood, and eggs or unpasteurized milk products. It is one of the most common food-borne infections in the United States. Anorectal and Bowel Movement Pathology An anal fissure is a small crack-like sore in the skin of the anus that can cause severe pain during a bowel movement. Fetal incontinence is the inability to control the excretion of feces. Constipation is defined as having a bowel movement fewer than three times per week. With constipation, stools are usually hard, dry, small in side, and difficult to pass. Constipation can be caused by a lack of fiber in the diet, disease, medication, and (especially in women) pelvic floor dysfunction. Pelvic floor dysfunction is the lack of coordination of the muscles needed for the rectum to straighten and the anal sphincter to relax. Diarrhea is an abnormally frequent flow of loose or water stools and can lead to dehydration. Hemorrhoids occur when a cluster of veins, muscles, and tissues slip near or through the anal  opening. These veins can become inflamed, resulting in pain, fecal leakage, itching, and bleeding. A rectocele is a bulging of the front wall of the rectum into the vagina, usually as the result of childbirth or pregnancy (-cele meand hernia). Abnormal Stools Hematochezia is the presence of bright red blood in the stool. This bright red color usually indicates that the blood is coming from the lower part of the gastrointestinal tract. Melena is the passage of black, tarry, foul-smelling stools. This appearance of the stool is caused by the presence of digested blood and often indicated bleeding in the upper part of the gastrointestinal tract. Steatorrhea is the presence of excess fat in the stool. This condition, which results in frothy, foul- smelling stools, is usually caused by pancreatic disease, the removal of the gallbladder, or malabsorption disorders. The Liver Liver disorders are a major concern because the functioning of the liver is essential to the digestive process. Ascites is an abnormal accumulation of serous fluid in the peritoneal cavity. This condition is usually the result of severe liver disease creating pressure on the liver’s blood vessels. Hepatomegaly is the abnormal enlargement of the liver. Jaundice is a yellow discoloration of the skin, mucous membranes, and eyes. This condition is caused by grater-than-normal amounts of bilirubin in the blood. Hepatitis is an inflammation of the liver usually caused by a viral infection. Viral hepatitis is the leading cause of liver cancer and the most common reason for liver transplants. ◦HAV= Hepatitis A virus is the most prevalent type of hepatitis. This highly contagious condition is transmitted mainly through contamination of food and water with infected fecal matter. A vaccine is available to provide immunity against HAV. ◦HBV= Hepatitis B virus is a bloodborne disease that is transmitted through contact with blood and other body fluids that are contaminated with this virus. A vaccine is available to provide immunity agains HBV. ◦HCV= Hepatitis C virus is a bloodborne disease that is spread through contact with blood and other body fluids that care contaminated with this virus. HCV is described as a silent epidemic because it can be present in the body for years and destroy the liver before any symptoms appear. There is no vaccine available to prevent this form of hepatitis. Cirrhosis Cirrhosis is a chronic degenerative disease of the liver characterized by scarring. Degenerative means progressive deterioration resulting in the loss of tissue or organ function. Cirrhosis is often caused by excessive alcohol abuse or by viral hepatitis B or C. the progress of cirrhosis is marked by the formation of areas of scarred liver tissue that are filled with fat. The liver damage causes abnormal conditions throughout the other body systems. Nonalcoholic Fatty Liver Disease The term nonalcoholic fatty liver disease (NAFLD) describes the accumulation of fat in the liver and is not associated with alcohol consumption. NAFLD is the leading liver disorder in the US. Patients with this disease usually have no signs or symptoms. Common comorbidities include obesity, type 2 diabetes, and high cholesterol. Nonalcoholic steatohepatitis is a more serious form of this condition because is consists of fatty accumulations plus liver-damaging inflammation (steat/o means fat). In some cases, this will progress to cirrhosis, irreversible liver scarring, or liver cancer. The Gallbladder Cholangitis is an acute inflammation of the bile duct characterized by pain in the right upper quadrant of the abdomen, fever, and jaundice (cholang means bile duct). The most common cause is a bacterial infection Cholecystitis is inflammation of the gallbladder, usually associated with gallstones blocking the flow of bile (cholecyst means gallbladder). A gallstone (cholelith) is a hard deposit formed in the gallbladder and bile ducts due to the concretion of bile components. Cholelithiasis is the presence of gallstones in the gallbladder or bile ducts. Pain caused by the passage of a gallstone through the bile duct is called biliary colic. Diagnostic Procedures of the Digestive System Abdominal computed tomography (CT) is a radiographic procedure that used x-rays to produce a detailed cross-section of the tissue structure within the abdomen, showing, for example, the presence of a tumor or obstruction. An abdominal ultrasound is a noninvasive test used to visualize internal organs by using very high-frequency sound waves. Cholangiography is a radiographic examination of the bile ducts with the use of a contrast medium. This test is used to identify obstructions in the liver or bile ducts that slow or block the flow of bile from the liver. The resulting record is a cholangiogram. An enema is the placement of a solution into the rectum and colon to empty the lower intestine through bowel activity. An enema is sometimes part of the preparation for an endoscopic examination; however, enemas are also used to treat severe constipation and as a means of administering medication Esophagogastroduodenoscopy (EGD) is an endoscopic procedure that allows direct visualization of the upper GI tract. This includes the esophagus, stomach, and upper duodenum. A barium swallow study is a video fluoroscopy test using barium-coated foods or barium- containing liquids of various thickness to observe whether there is a danger of food being aspirated into the lungs. The upper GI series and a lower GI series are radiographic studies to examine the digestive system. A contrast medium called barium is required to make these structures visible, allowing the flow of the barium to be traced using radiography or fluoroscopy. A barium swallow is used for the upper GI series, and a barium enema is used for the lower GI series. Stool tests use a specimen of feces to examine for content and characteristics. Abnormal findings such as blood, fat, nutrients, bacteria, or parasites in the stool can help diagnose disease or malabsorption. A blood test can determine blood nutrient levels, sometimes used to test for deficiencies. A breath test can be used to diagnose certain intestinal disorders and is named for the gas being tested. For example, thes test for lactose intolerance is called a hydrogen breath test because hydrogen is found in excess level when ingested lactose is not broken down. A breath test can also diagnose small intestine bacterial overgrowth, fructose intolerance, and Helicobacter pylori infection. Endoscopic Procedures An endoscope is an instrument used for a visual examination of internal structures. This examination is called an endoscopy. An anoscopy is the visual examination of the anal canal and lower rectum. A capsule endoscopy is the use of a tiny video camera in a capsule that the patient swallows. For approximately 8 hours, as it passes through the small intestine, this camera transmits images of the walls of the small intestine. The images are detected by sensor devices attached to the  patient’s abdomen and transmitted to a data recorder worn on the patient’s belt. Colon Screening The following diagnostic tests can be used for the early detection of polyps that may cause colorectal carcinoma. A colonoscopy is the direct visual examination of the inner surface of the entire colon from the rectum to the cecum using a colonoscope. In a virtual colonoscopy, a small, flexible tube is inserted into the rectum and an MRI or CT machine is used to produce two- and three-dimensional images of the colon. The preparation, which requires that bowels be completely emptied, is the same for both of these types of colonoscopy and the sigmoidoscopy. A sigmoidoscopy is the endoscopic examination of the interior of the rectum, the sigmoid colon, and possibly a portion of the descending colon. A Hemoccult test (fecal occult blood test), is a laboratory test for hidden blood in stool. The test kit is used to obtain the specimens at home, and the results are then evaluated in a laboratory. Cologuard is a recently developed, noninvasive, collect-at-home stool test that uses DNA testing along with screening for hidden blood to determine the potential presence of colorectal cancer. Treatment Procedures of the Digestive System The Oral Cavity and Esophagus A dental prophylaxis is the professional examining, cleaning, and polishing of the gums and teeth to remove plaque and tartar. Often this includes x-rays to look for cavities. The term prophylaxis refers to disease prevention. Examples include vaccination to provide immunity against a specific disease. A filling is the restoration of a decaying tooth by removing the damaged area and replacing it with material to fill it such as amalgam from metal or composite from resin to match the tooth Orthodontics is the treatment of alignment and malocclusion of the teeth and jaw. Braces and retainers are hardware used for this purpose. A dental implant is the anchoring or a crown, bridge, or denture to the bone of the jaw. Crowns bridges, and dentures can also be placed in the mouth without being anchored to the jaw. ◦A crown is a metal or porcelain alloy cap shaped like a tooth cemented over a damaged tooth structure. ◦A bridge is a fixed dental prosthesis used to join one or more artificial teeth to the adjacent teeth. ◦A denture is a plate holding one or more replacement teeth. Conventional dentures, also known as a full or partial set of false teeth, are removable. An occlusal splint is a specially designed mouth guard worn at night to prevent grinding the teeth. Scaling and root planing is the removal of plaque and tartar below the gum line for the treatment of gum disease. The term root canal refers both to the pulp cavity in the root of the tooth and to a procedure in which diseased or damaged pulp in the tooth canal in removed in order to save the tooth. After it is free of infection, the cavity is filled with a protective substance and sealed. A gingivectomy is the surgical removal of diseased gingival tissue. Maxillofacial surgery is specialized surgery of the face and jaws to correct deformities, treat diseases, and repair injuries. Palatoplasty is surgical repair of a cleft palate, also used to refer to the repair of a cleft lip. Antioxidants and Probiotics Antioxidants are chemicals such as vitamins A, C, and E; carotene; and lute in that may prevent  or delay cell damage by blocking the activity of potentially harmful chemical called free radicals. Antioxidants are naturally present in fruit, beans, berries, nuts, and dark chocolate. Probiotics are living microorganisms sometimes described as “good” bacteria because of their role in aiding digestion and protecting the body from harmful bacteria. Probiotics are found in fermented food and beverages such as yogurt, sauerkraut, and kombucha. Prebiotics are the non digestible carbohydrates that probiotics feed on and are found in fruits, vegetables, and whole grains. Some foods and supplements contain both probiotics and prebiotics. Medications Antacids which neutralize the acids in the stomach, are taken to relieve the discomfort of conditions such as pyrosis or to help peptic ulcers heal. Proton pump inhibitors block the action of the enzyme in the wall of the stomach that produces acid. These medications are used to treat symptoms of GERD An antiemetic is a medication that is administered to prevent or relieve nausea and vomiting. Laxatives are medications or foods given to stimulate bowel movements. Bulk-forming laxatives, such as bran, treat constipation by helping fecal matter retain water and remain soft as it moves through the intestines. Antimotility agents are over-the-counter medications that reduce diarrhea symptoms by slowing digestion, allowing for more water to be reabsorbed back into the body. Intravenous fluids (IV) are administered to combat the effects of dehydration. Oral rehydration therapy is a treatment in which a solution of electrolytes is administered in a liquid reparation to counteract the dehydration that can accompany diarrhea, especially in young children. Nutrition Support Nutrition support is helping a person get the nutrients they need through whatever means possible, such as by mouth (food), via tube (formula), or by vein (solution). This might be food- or nutrient- specific such as prescribing a gluten-free diet to some with celiac disease. or, it could be addressing inadequate caloric intake such as prescribing an increase in calories for someone with anorexia or failure to thrive. Enteral nutrition is feeding using the digestive system either through eating and drinking by mouth or via tube feeding. Tube feedings may be given bolus, a large amount in a short period of time, or continuous, providing calories throughout the day and/or night. Nasogastric intubation is the placement of a nasogastric feeding tube through the nose and into the stomach. This temporary tube provides nutrition for patients who cannot take sufficient nutrients by mouth. A gastrostomy tube is a surgically placed feeding tube from the exterior of the body on the abdomen, directly into the stomp. This is also known as a g-tube, and it is used long term to provide nutrition for patients who cannot swallow or take sufficient nutrients by mouth. A jejunostomy tube is silimar but placed from the abdomen into the small intestine rather than the stomach. Parenteral nutrition or total parenteral nutrition (TPN) is administered to patients who cannot or should not get their nutrition through the digestive system. Some or all of the patient’s nutritional requirements are met through a a specialized solution administered intravenously. Parenteral means not in or through the digestive system. Bariatric Surgery Bariatric surgery is performed to treat severe obesity by restricting the amount of food that can enter the stomach and be digested. This procedure limits food intake, decreases absorption, and forces a reduction in dietary intake in order to enable weight loss. Gastric bypass surgery makes the stomach smaller by stapling a section to create a small pouch and causes food to bypass the first part of the small intestine. This procedure, which is the most common form of Bariatric surgery, is not reversible and carries some risk of complications. The lap-band or adjustable gastric banding procedure involves placing an inflatable band around the exterior of the stomach to restrict the amount of food that can enter. This procedure has the advantage of being reversible through the removal of the band. Sleeve gastrectomy is one of several endoscopic options for Bariatric surgeries require ig general anesthesia. In this procedure, the stomach is sutured to make it into a small tube, reducing its capacity by 75%. The Intestines A colectomy is the surgical removal of all or part of the colon. A diverticulectomy is the surgical removal of a diverticulum. A gastroduodenostomy is the establishment of an anastomosis between the upper portion of the stomach and the duodenum. This procedure is performed to treat stomach cancer or to remove a malfunctioning pyloric valve. An anastomosis is a surgical connection between two hollow, or tubular, structures. An ileectomy is the surgical removal of the ileum. Fecal microbiota transplantation (fecal transplant therapy) is the transplant of still from a healthy donor, used to restore gut bacteria. This is used for patients whose frequent antibiotic use to treat C. Difficile infection has wiped out good bacteria and is being studied to treat other conditions such as IBD Ostomies An ostomy is a surgical procedure to create an artificial opening between an organ and the body surface. This artificial opening is also known as a stoma. Ostomy can be used alone as a noun to describe a procedure or as a sufficient with the word part that describes the organ involved. An ileostomy is the surgical creation of an artificial excretory opening between the ileum, at the end of the small intestine, and the outside of the abdominal wall. A colostomy is the surgical creation of an artificial excretory opening between the colon and the body surface. The segment of the intestine below the ostomy is usually removed, and the fecal matter flows through the stoma into a disposable bag. A colostomy can be permanent or temporary to divert feces from an area that needs to heal. The Rectum and Anus A hemorrhoidectomy is the surgical removal of hemorrhoids. Rubber band ligation can be done instead of surgery. Rubber bands cut off the circulation at the base of an internal hemorrhoid, causing it to eventually fall off. Ligation means the tying off of blood vessels or ducts. The Liver A hepatectomy is the surgical removal of all or part of the liver. A liver transplant is an option for a patient whose liver has failed for a reason other than liver cancer. Because liver tissue regenerates, a partial liver transplant, in which only part of the organ i donated, can ne adequate. A partial liver can be donated by living donor whose blood and tissue types match. The Gallbladder A cholecystectomy is the surgical removal of the gallbladder, which is not necessary for survival. An open cholecystectomy is performed through an incision in the right side of the upper  abdomen. A laparoscopic cholecystectomy, also known as a lap choley, is the surgical removal of the gallbladder using a laparoscope and other instruments inserted through three of four small incisions in the abdominal wall. This is performed for the treatment of gallstones,which can commonly reoccur without surgical intervention. Abbreviations Related to the Digestive system BMI= body mass index EGD= esophagogastroduodenoscopy FTT= failure to thrive FMT= fecal microbiota transplantation GERD= gastroesophageal reflux disease GI= gastrointestinal IH= inguinal hernia IBD= inflammatory bowl disease IBS= irritable bowl syndrome NG tube= nasogastric tube NAFLD= nonalcoholic fatty liver disease PUD=peptic ulcer disease PN= parenteral nutrition UC= ulcerative colitis