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How Gastroenterologists Were Selected Consumers' Research Council of America has compiled a list of Top Gastroenterologists throughout the United States by utilizing a point value system. This method uses a point value for criteria that we deemed valuable in determining Top Gastroenterologists. The criteria that was used and assessed a point value is as follows:
Similar studies have been done with other professions using a survey system. This type of study would ask fellow professionals whom they would recommend. We found this method to be more of a popularity contest, for instance: professionals who work in a large office have much more of a chance of being mentioned as opposed to a professional who has a small private practice. In addition, many professionals have a financial arrangement for back-and-forth referrals. For these reasons, we developed the point value system. Since this is a subjective call, there is no study that is 100% accurate. As with any profession, there will be some degree of variance in opinion. If you survey 100 patients from a particular physician on their satisfaction, you will undoubtedly hear that some are very satisfied, some moderately satisfied and some dissatisfied. This is really quite normal. We feel that a point value system takes out the personal and emotional factor and deals with factual criteria. We have made certain assumptions. For example, we feel that the more years in practice is better than less years in practice; more education is better than less education, etc. The Top Gastroenterologists list that we have compiled is current as of a certain date and other Gastroenterologists may have qualified since that date. Nonetheless, we feel that the list of Top Gastroenterologists is a good reference of qualified specialists. No fees, donations, sponsorships or advertising are accepted from any individuals, professionals, corporations or associations. This policy is strictly adhered to, insuring an unbiased selection.
Choosing a Gastroenterologist
First of all, when selecting a Gastroenterologist, you may want to begin your search several different ways:
What is
Gastroenterology? Gastroenterology is the branch of medicine where the digestive system and its disorders are studied. Etymologically it is the combination of Ancient Greek words gastros (stomach), enteron (intestine) and logos (reason). Diseases affecting gastrointestinal tract (i.e. organs from mouth to anus) are the focus of this speciality. Doctors specializing in the field are called Gastroenterologists. Important advances are made in the last 50 years, contributing to rapid expansion of its scope. Hepatology or hepatobiliary medicine encompasses the study of the liver, pancreas and biliary tree and is traditionally considered a subspecialty. History Citing from Egyptian papyri, Nunn identified significant knowledge of gastrointestinal diseases among practicing doctors in Pharaoh periods. Irynakhty, of the tenth dynasty c. 2125 BC was a court physician specializing in gastroenterology and proctology. Among ancient Greeks, Hippocrates attributed digestion to concoction. Galen's concept of the stomach having four faculties was widely accepted up to modernity. 18th century:
19th century:
20th century:
Anatomical Range of Gastroenterology The Salivary Gland
Function Saliva keeps the mouth and other parts of the digestive system moist. Saliva also helps break down carbohydrates (with salivary amylase, formerly known as ptyalin) and lubricates the passage of food down from the oropharynx to the stomach. Saliva also has elements that help to neutralize the acid responsible for tooth decay; this is called buffer action (antacid). The antibacterial properties within saliva help to sustain a neutral balance and prevent the development of germs. Histology The glands are enclosed in a capsule of connective tissue and internally divided into lobules. Blood vessels and nerves enter the glands at the hilum and gradually branch out into the lobules. Cells There are 3 main types of cells that are found in the major salivary glands:
Ducts In the duct system, the lumens formed by the secretory cells empty into intercalated ducts, which in turn join to form striated ducts. These drain into ducts situated between the lobes of the gland (called interlobar ducts or excretory ducts). The main duct of the salivary glands ultimately empties into the mouth. Innervation Salivary glands are innervated, either directly or indirectly, by the parasympathetic and sympathetic arms of the autonomic nervous system.
Role in disease Salivary duct calculus may cause blockage of the ducts, causing pain and swelling of the gland. Tumors of the salivary glands may occur. These are usually benign, but may be malignant. The most common type of benign tumor is pleomorphic adenoma, followed by Warthin's tumor. The most common malignant tumor is mucoepidermoid carcinoma.
The Esophagus
Function Food is passed through the esophagus by using the process of peristalsis. Specifically, in mammals, it connects the pharynx, which is the body cavity that is common to the digestive system and respiratory system behind the mouth, with the stomach, where the second stage of digestion is initiated (the first stage of digestion is in the mouth, with teeth and tongue masticating food and mixing it with saliva).
Histology The layers of the esophagus are as follows:
Gastroesophageal junction The junction between the esophagus and the stomach (the gastroesophageal junction or GE junction) is not actually considered a valve, although it is sometimes called the cardiac sphincter, cardia or cardias, but is actually more of a stricture.
Many people experience a burning sensation in their throat occasionally, caused by fluids moving quickly in the throat creating excessive friction, normally called heartburn. Extended exposure to heartburn may erode the lining of the esophagus, leading to a potentially cancerous condition called Barrett's esophagus. Some people also experience a sensation known as globus esophagus, where it feels as if a ball is lodged in the lower part of the esophagus.
The Stomach
Functions The stomach is usually a highly acidic environment due to gastric acid production and secretion which produces a luminal pH range usually between 1 and 4 depending on the species, food intake, time of the day, drug use, and other factors. Such an environment is able to break down large molecules (such as from food) to smaller ones so that they can eventually be absorbed from the small intestine. The human stomach can produce and secrete about 2 to 3 liters of gastric acid per day with basal secretion levels being typically highest in the evening. Pepsinogen is secreted by chief cells and turns into pepsin under low pH conditions and is a necessity in protein digestion. Absorption of vitamin B12 from the small intestine is dependent on conjugation to a glycoprotein called intrinsic factor which is produced by parietal cells of the stomach. Other functions include absorbing some ions, water, and some lipid soluble compounds such as alcohol, aspirin, and caffeine. Another function of the stomach is simply a food storage cavity. Anatomy of the human stomach
Two smooth muscle valves, or sphincters, keep the contents of the stomach contained. They are the esophageal sphincter (found in the cardiac region) dividing the tract above, and the Pyloric sphincter dividing the stomach from the small intestine. The stomach is surrounded by parasympathetic (stimulant) and orthosympathetic (inhibitor) plexuses (anterior gastric, posterior, superior and inferior, celiac and myenteric), which regulate both the secretory activity and the motor activity of the muscles. In humans, the stomach has a volume of about 50 mL when empty. After a meal, it generally expands to hold about 1 liter of food, but it can actually expand to hold as much as 4 liters. When drinking milk it can expand to just under 6 pints, or 3.4 liters. Sections The stomach is divided into four sections, each of which has different cells and functions. The sections are:
Blood supply The lesser curvature of the stomach is supplied by the right gastric artery inferiorly, and the left gastric artery superiorly, which also supplies the cardiac region. The greater curvature is supplied by the right gastroepiploic artery inferiorly and the left gastroepiploic artery superiorly. The fundus of the stomach, and also the upper portion of the greater curvature, are supplied by the short gastric artery Histology of the human stomach Layers Like the other parts of the gastrointestinal tract, the stomach walls are made of the following layers, from inside to outside:
Glands The epithelium of the stomach forms deep pits. The glands at these locations are named for the corresponding part of the stomach:
Control of secretion and motility The movement and the flow of chemicals into the stomach are controlled by both the autonomic nervous system and by the various digestive system hormones:
Other than gastrin, these hormones all act to turn off the stomach action. This is in response to food products in the liver and gall bladder, which have not yet been absorbed. The stomach needs only to push food into the small intestine when the intestine is not busy. While the intestine is full and still digesting food, the stomach acts as storage for food. Diseases of the stomach
Having too little or no gastric acid is known as hypochlorhydria or achlorhydria respectively and are conditions which can have negative health impacts. Having high levels of gastric acid is called hyperchlorhydria. Many people believe that hyperchlorhydria can cause stomach ulcers. However, recent research indicates that the gastric mucosa which secretes gastric acid is acid-resistant. Differences among animals In ruminants, such as bovines, the stomach is a large multichamber organ which hosts symbiotic bacteria that produce enzymes required for the digestion of cellulose from plant matter, primarily cellulase. The partially digested plant matter passes through each of the intestine chambers in sequence, being regurgitated and rechewed at least once in the process. In some animals (such as cats and dogs), the pH of the lumen is lower, usually between 1 and 2. In contrast, the human stomach pH is usually between 2 and 3.
The Pancreas
Anatomy In humans, the pancreas is a 15-25 cm (6-10 inch) elongated organ in the abdomen. One of the organs behind the abdominal cavity, it is located posterior to the stomach and in close association with the duodenum. It is often described as having four regions: a head, neck, body and tail.
The pancreatic duct (also called the duct of Wirsung) runs the length of the pancreas and empties into the second part of the duodenum at the ampulla of Vater. The common bile duct usually joins the pancreatic duct at or near this point. Many people also have a small accessory duct, the duct of Santorini, which extends from the main duct more upstream (towards the tail) to the duodenum, joining it more proximal than the ampulla of Vater. Blood supply The pancreas is supplied arterially by the Pancreaticoduodenal arteries and the splenic artery:
Nerves The pancreas is innervated by the pancreatic plexus; a subdivision of the celiac plexus that accompanies pancreatic arteries. Endocrine There are four main types of cells in the islets of Langerhans. They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion:
The islets are a compact collection of endocrine cells arranged in clusters and cords and are crisscrossed by a dense network of capillaries. The capillaries of the islets are lined by layers of endocrine cells in direct contact with vessels, and most endocrine cells are in direct contact with blood vessels, by either cytoplasmic processes or by direct apposition. According to the volume The Body, by Alan E. Nourse, in the Time-Life Science Library Series, the islets are "busily manufacturing their hormone and generally disregarding the pancreatic cells all around them, as though they were located in some completely different part of the body." Exocrine There are two main types of exocrine pancreatic cells, responsible for two main classes of secretions:
Diseases of the pancreas Due to the importance of its enzyme contents, injury to the pancreas is potentially very dangerous. A puncture of the pancreas generally requires prompt and experienced medical intervention. Diseases associated with the pancreas include: Diabetes mellitus Diabetes mellitus is a metabolic disorder characterized by hyperglycemia. All three forms of the disease are due to the inability of the beta cells of the pancreas to produce sufficient insulin. Researchers at the Toronto Hospital for Sick Children injected capsaicin into NOD mice (Non-obese diabetic mice, a strain that is genetically predisposed to develop the equivalent of diabetes mellitus type 1) to kill the pancreatic sensory nerves. This treatment reduced the development of diabetes mellitus in these mice by 80%, suggesting a link between neuropeptides and the development of diabetes. When the researchers injected the pancreas of the diabetic mice with sensory neuropeptide (sP), they were cured of the diabetes for as long as 4 months. Also, insulin resistance (characteristic of diabetes mellitus type 2) was reduced. Benign tumors Like any other organ, the pancreas is susceptible to the growth of benign tumors. Benign tumors do not invade neighboring tissues, do not cause metastases, and usually do not return after surgical removal. Pancreatic cancer Pancreatic cancer is a malignant tumour within the pancreatic gland. Its prognosis is generally regarded as poor. The different types of pancreatic cancers include:
Cystic fibrosis Cystic fibrosis, also known as mucoviscidosis, is a hereditary disease that affects the entire body, causing progressive disability and early death. There is no cure for cystic fibrosis, and most affected individuals die young from lung failure. Cystic fibrosis is caused by a mutation in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR). The product of this gene helps create sweat, digestive juices, and mucus. Although most people without CF have two working copies of the CFTR gene, only one is needed to prevent cystic fibrosis. Cystic fibrosis develops when neither gene works normally. Therefore, it is considered an autosomal recessive disease. The name cystic fibrosis refers to the characteristic 'fibrosis' (tissue scarring) and cyst formation within the pancreas. Cystic fibrosis causes irreversible damage to the pancreas, which often results in painful inflammation (pancreatitis). Exocrine pancreatic insufficiency Exocrine pancreatic insufficiency (EPI) is the inability to properly digest food due to a lack of digestive enzymes made by the pancreas. EPI is found in humans afflicted with cystic fibrosis. It is caused by a progressive loss of the pancreatic cells that make digestive enzymes. Chronic pancreatitis is the most common cause of EPI in humans. Loss of digestive enzymes leads to maldigestion and malabsorption of nutrients. Hemosuccus pancreaticus Hemosuccus pancreaticus, also known as pseudohematobilia or Wirsungorrhage, is a rare cause of hemorrhage in the gastrointestinal tract. It is caused by a bleeding source in the pancreas, pancreatic duct, or structures adjacent to the pancreas, such as the splenic artery, that bleed into the pancreatic duct. Patients with hemosuccus may develop symptoms of gastrointestinal hemorrhage, such as blood in the stools, maroon stools, or melena. They may also develop abdominal pain. Hemosuccus pancreaticus is associated with pancreatitis, pancreatic cancer and aneurysms of the splenic artery. Angiography may be used to treat hemosuccus pancreaticus, where the celiac axis is injected to determine the blood vessel that is bleeding, because embolization of the end vessel may terminate the hemorrhage. Alternatively, a distal pancreatectomy may be required to stop the hemorrhage. Pancreatitis Pancreatitis is inflammation of the pancreas. There are three forms of pancreatitis, which are different in causes and symptoms, and require different treatment:
History The pancreas was discovered by Herophilus (335-280 BC), a Greek anatomist and surgeon. Only a few hundred years later, Ruphos, another Greek anatomist, gave the pancreas its name. The term "pancreas" is derived from the Greek pan, "all", and kreas, "flesh", probably referring to the organ's homogeneous appearance. Pancreas as a food Pancreases (specifically calf and lamb pancreases) are used in some meals often going by the name stomach sweetbreads.
The Liver
Anatomy The adult human liver normally weighs between 1.4 - 1.6 kilograms (3.1 - 3.5 pounds), and it is a soft, pinkish-brown "boomerang shaped" organ. It is the second largest organ (the largest organ being the skin) and the largest gland within the human body. It is located on the right side of the upper abdomen below the diaphragm. The liver lies on the right of the stomach and makes a kind of bed for the gallbladder (which stores bile). Flow of blood The splenic vein, joins the inferior mesenteric vein, which then together join with the superior mesenteric vein to form the portal vein, bringing venous blood from the spleen, pancreas, small intestine, and large intestine, so that the liver can process the nutrients and byproducts of food digestion. The hepatic veins drain directly into the inferior vena cava. The hepatic artery is generally a branch from the celiac trunk, although occasionally some or all of the blood can be from other branches such as the superior mesenteric artery. Approximately 60% to 80% of the blood flow to the liver is from the portal venous system, and 1/4 is from the hepatic artery. Flow of bile The bile produced in the liver is collected in bile canaliculi, which merge to form bile ducts. These eventually drain into the right and left hepatic ducts, which in turn merge to form the common hepatic duct. The cystic duct (from the gallbladder) joins with the common hepatic duct to form the common bile duct. Bile can either drain directly into the duodenum via the common bile duct or be temporarily stored in the gallbladder via the cystic duct. The common bile duct and the pancreatic duct enter the duodenum together at the ampulla of Vater. The branchings of the bile ducts resemble those of a tree, and indeed the term "biliary tree" is commonly used in this setting. Regeneration The liver is among the few internal human organs capable of natural regeneration of lost tissue; as little as 25% of remaining liver can regenerate into a whole liver again. This is predominantly due to the hepatocytes acting as unipotential stem cells (i.e. a single hepatocyte can divide into two hepatocyte daughter cells). There is also some evidence of bipotential stem cells, called oval cells, which can differentiate into either hepatocytes or cholangiocytes (cells that line the bile ducts). Peritoneal ligaments Apart from a patch where it connects to the diaphragm, the liver is covered entirely by visceral peritoneum, a thin, double-layered membrane that reduces friction against other organs. The peritoneum folds back on itself to form the falciform ligament and the right and left triangular ligaments. These "ligaments" are in no way related to the true anatomic ligaments in joints, and have essentially no functional importance, but they are easily recognizable surface landmarks. Lobes Traditional gross anatomy divided the liver into four lobes based on surface features. The falciform ligament is visible on the front (anterior side) of the liver. This divides the liver into a left anatomical lobe, and a right anatomical lobe. If the liver flipped over, to look at it from behind (the visceral surface), there are two additional lobes between the right and left. These are the caudate lobe (the more superior), and below this the quadrate lobe. From behind, the lobes are divided up by the ligamentum venosum and ligamentum teres (anything left of these is the left lobe), the transverse fissure (or porta hepatis) divides the caudate from the quadrate lobe, and the right sagittal fossa, which the inferior vena cava runs over, separates these two lobes from the right lobe. Each of the lobes is made up of lobules, a vein goes from the centre of each lobule which then joins to the hepatic vein to carry blood out from the liver. On the surface of the lobules there are ducts, veins and arteries that carry fluids to and from them. Modern (Functional) anatomy The central area where the common bile duct, portal vein, and hepatic artery enter the liver is the hilum or "porta hepatis". The duct, vein, and artery divide into left and right branches, and the portions of the liver supplied by these branches constitute the functional left and right lobes. The functional lobes are separated by a plane joining the gallbladder fossa to the inferior vena cava. This separates the liver into the true right and left lobes. The middle hepatic vein also demarcates the true right and left lobes. The right lobe is further divided into an anterior and posterior segment by the right hepatic vein. The left lobe is divided into the medial and lateral segments by the left hepatic vein. The fissure for the ligamentum teres (the ligamentum teres becomes the falciform ligament) also separates the medial and lateral segments. The medial segment is what used to be called the quadrate lobe. In the widely used Couinaud or "French" system, the functional lobes are further divided into a total of eight subsegments based on a transverse plane through the bifurcation of the main portal vein. The caudate lobe is a separate structure which receives blood flow from both the right- and left-sided vascular branches. The various functions of the liver are carried out by the liver cells or hepatocytes.
Currently, there is no artificial organ or device capable of emulating all the functions of the liver. Some functions can be emulated by liver dialysis, an experimental treatment for liver failure. Diseases of the liver Many diseases of the liver are accompanied by jaundice caused by increased levels of bilirubin in the system. The bilirubin results from the breakup of the hemoglobin of dead red blood cells; normally, the liver removes bilirubin from the blood and excretes it through bile.
There are also many pediatric liver diseases, including biliary atresia, alpha-1 antitrypsin deficiency, alagille syndrome, and progressive familial intrahepatic cholestasis, to name but a few. A number of liver function tests are available to test the proper function of the liver. These test for the presence of enzymes in blood that are normally most abundant in liver tissue, metabolites or products. Liver transplantation
Liver allografts for transplant usually come from non-living donors who have died from fatal brain injury. Living donor liver transplantation is a technique in which a portion of a living person's liver is removed and used to replace the entire liver of the recipient. This was first performed in 1989 for pediatric liver transplantation. Only 20% of an adult's liver (Couinaud segments 2 and 3) is needed to serve as a liver allograft for an infant or small child. More recently, adult-to-adult liver transplantation has been done using the donor's right hepatic lobe which amounts to 60% of the liver. Due to the ability of the liver to regenerate, both the donor and recipient end up with normal liver function if all goes well. This procedure is more controversial as it entails performing a much larger operation on the donor, and indeed there have been at least 2 donor deaths out of the first several hundred cases. A recent publication has addressed the problem of donor mortality, and at least 14 cases have been found. The risk of postoperative complications (and death) is far greater in right sided hepatectomy than left sided operations. Development The liver develops as an endodermal outpocketing of the foregut called the hepatic diverticulum. Its initial blood supply is primarily from the vitelline veins that drain blood from the yolk sac. The superior part of the hepatic diverticulum gives rise to the hepatocytes and bile ducts, while the inferior part becomes the gallbladder and its associated cystic duct. Fetal blood supply In the growing fetus, a major source of blood to the liver is the umbilical vein which supplies nutrients to the growing fetus. The umbilical vein enters the abdomen at the umbilicus, and passes upward along the free margin of the falciform ligament of the liver to the inferior surface of the liver. There it joins with the left branch of the portal vein. The ductus venosus carries blood from the left portal vein to the left hepatic vein and then to the inferior vena cava, allowing placental blood to bypass the liver. In the fetus, the liver develops throughout normal gestation, and does not perform the normal filtration of the infant liver. The liver does not perform digestive processes because the fetus does not consume meals directly, but receives nourishment from the mother via the placenta. The fetal liver releases some blood stem cells that migrate to the fetal thymus, so initially the lymphocytes, called T-cells, are created from fetal liver stem cells. Once the fetus is delivered, the formation of blood stem cells in infants shifts to the red bone marrow. After birth, the umbilical vein and ductus venosus are completely obliterated two to five days postpartum; the former becomes the ligamentum teres and the latter becomes the ligamentum venosum. In the disease state of cirrhosis and portal hypertension, the umbilical vein can open up again. Liver as food Mammal and bird livers are commonly eaten as food: products include liver pâté, Leberwurst, Braunschweiger, foie gras, chopped liver, liver and onions, leverpostej and liver sashimi. Both animal and fish livers are rich in iron and Vitamin A and cod liver oil is commonly used as a supplement. Very high doses of Vitamin A can be toxic; Antarctic explorers Douglas Mawson and Xavier Mertz were both poisoned, the latter fatally, from eating husky liver. In the US, the USDA specifies 3000g per day as a tolerable upper limit, which amounts to about 50 g of raw pork liver or, as reported in a non scientific source, 3g of polar-bear liver. However, acute vitamin A poisoning is not likely to result from liver consumption, since it is present in a less toxic form than in many dietary supplements. Cultural allusions In Greek mythology, Prometheus was punished by the gods for revealing fire to humans by being chained to a rock where a vulture (or an eagle, Ethon) would peck out his liver, which would regenerate overnight. Curiously, the liver is the only human internal organ that actually can regenerate itself to a significant extent; this characteristic may have already been known to the Greeks due to survived injuries in battle. The Talmud (tractate Berakhot 61b) refers to the liver as the seat of anger, with the gallbladder counteracting this. In Arabic and Persian language, the liver is used in figurative speech to refer to courage and strong feelings, or "their best," e.g. "This Mecca has thrown to you the pieces of its liver!" The legend of Liver-Eating Johnson says that he would cut out and eat the liver of each man killed. In the motion picture The Message, Hind bint Utbah is implied or portrayed eating the liver of Hamza ibn ‘Abd al-Muttalib during the Battle of Uhud. Inuit will not eat the liver of polar bears (due to the fact a polar bears liver contains so much Vitamin A as to be virtually poisonous to humans) or seals In The Silence of the Lambs, Hannibal Lecter says famously, "I ate his liver with some fava beans and a nice Chianti."
Gallbladder
Anatomy The gallbladder is about 10-12 cm long in humans and appears dark green because of its contents (bile), rather than its tissue. It is connected to the liver and the duodenum by the biliary tract.
Microscopic anatomy The different layers of the gallbladder are as follows:
Function The gallbladder stores about 50ml of bile (1.7 US fluid ounces / 1.8 Imperial fluid ounces), which is released when food containing fat enters the digestive tract, stimulating the secretion of cholecystokinin (CCK). The bile, produced in the liver, emulsifies fats and neutralizes acids in partly digested food. After being stored in the gallbladder, the bile becomes more concentrated than when it left the liver, increasing its potency and intensifying its effect on fats. Most digestion occurs in the duodenum. Role in disease
The Intestine In anatomy, the intestine is the segment of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. In humans, the small intestine is further subdivided into the duodenum, jejunum and ileum while the large intestine is subdivided into the cecum and colon. Structure and Function
The next layer is the muscularis mucosa which is a layer of smooth muscle that aids in the action of continued peristalsis along the gut. The submucosa contains nerves, blood vessels and elastic fiber with collagen that stretches with increased capacity but maintains the shape of the intestine. Surrounding this is the muscularis externa which comprises longitudinal and smooth muscle that again helps with continued peristalsis and the movement of digested material out of and along the gut. Lastly there is the serosa which is made up of loose connective tissue and coated in mucus so as to prevent friction damage from the intestine rubbing against other tissue. Holding all this in place are the mesenteries which suspend the intestine in the abdominal cavity and stop it being disturbed when a person is physically active. The large intestine hosts several kinds of bacteria that deal with molecules the human body is not able to breakdown itself. This is an example of symbiosis. These bacteria also account for the production of gases inside our intestine (this gas is released as flatulence when removed through the anus). However the large intestine is mainly concerned with the absorption of water from digested material (which is regulated by the hypothalamus), the reabsorption of sodium, as well as any nutrients that may have escaped primary digestion in the ileum. Absorption of glucose in the ileum Initially, nutrients diffuse passively from the lumen of the ileum via the epithelial cells and into the blood stream. However, certain molecules like glucose passively diffuse in mass quantity some time after a meal, causing a change in concentration gradient. This results in a higher concentration of glucose in the blood (blood sugar level) than in the ileum, such that passive diffusion is no longer possible. Active uptake would be a waste of energy, so another process is used to transport the left-over glucose from the lumen into the blood stream. In this process, called secondary active transport, a glucose molecule associates with a sodium ion and approaches a transporter protein in the membrane of an epithelial cell. The protein allows the sodium ion through, which then "pulls" the glucose molecule into the cell. Once inside the cell, the sodium and glucose dissociate, and the glucose molecule is free to diffuse passively from the cell into the blood stream (this is because the blood flowing past the cell has a lower blood sugar level than the cell cytoplasm). Diseases
Disorders
The Rectum
Role in human defecation The rectum intestinum acts as a temporary storage facility for feces. As the rectal walls expand due to the materials filling it from within, stretch receptors from the nervous system located in the rectal walls stimulate the desire to defecate. If the urge is not acted upon, the material in the rectum is often returned to the colon where more water is absorbed. If defecation is delayed for a prolonged period, constipation and hardened feces results. When the rectum becomes full the increase in intrarectal pressure forces the walls of the anal canal apart allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic waves propel the feces out of the rectum. The internal and external sphincter allow the feces to be passed by muscles pulling the anus up over the exiting feces. Medical procedures For the diagnosis of certain ailments, a rectal exam may be done. Suppositories may be inserted into the rectum as a route of administration for medicine. The endoscopic procedures colonoscopy and sigmoidoscopy are performed to diagnose diseases such as cancer. Temperature taking Body temperature can also be taken in the rectum. Rectal temperature can be taken by inserting a mercury thermometer for 3 to 5 minutes, or a digital thermometer until it "beeps", not more than 25 mm (1 inch) into the rectum via the anus. Due to recent concerns related to mercury poisoning, the use of mercury thermometers is now discouraged. Normal rectal temperature generally ranges from 36 to 38 °C (97.6 to 100.4 °F) and is about 0.5 °C (1 °F) above oral (mouth) temperature and about 1 °C (2 °F) above axillary (armpit) temperature. Many pediatricians recommend that parents take infants and toddler's temperature in the rectum for two reasons:
In recent years, the introduction of ear (tympanic) thermometers and changing attitudes on privacy and modesty have led some parents and doctors to discontinue taking rectal temperatures.
The Anus
The anus plays a role in sexuality, though attitudes towards anal sex vary and it is even illegal in some countries. The anus is also the site of potential infections and other conditions including cancer. The subject is often considered a taboo part of the body, and is known by a large number of usually vulgar slang terms. Anatomy of the anus and rectum The human anus is situated between the buttocks, posterior to the perineum. It has two anal sphincters, one internal, the other external. These hold the anus closed until the need arises to defecate. One sphincter consists of smooth muscle and its action is involuntary; the other consists of striated muscle and its action is voluntary. In many animals, the anus is surrounded by anal sacs. Role in defecation
To prevent diseases of the anus and to promote general hygiene, humans often clean the exterior of the anus after emptying the bowels. A rinse with water from a bidet or a wipe with toilet paper are often used for this purpose. Puberty During puberty, as testosterone triggers androgenic hair growth on the body, pubic hair begins to appear around the anus. Although initially sparse, it fills out by the end of puberty, if not earlier. Hygiene is important for good anal health and anal sex. Washing with a mild soap and water will keep the anus clean. Harsh soaps or wiping vigorously with toilet paper can irritate the skin around the anus, making it itchy or sore. Pinworms are sometimes the source of anal itching. Care should be taken not to strip the anus of natural oils that keep the skin around the opening supple and elastic. Penetration with a penis or sex toy can irritate or tear the inside of the anus. Lubrication is often recommended to ease penetration. The risk of injury to the anal sphincter should be a concern, which can lead on to lack of control of defecation and fecal incontinence. Similarly if the anus is torn, this can occasionally cause a fistula formation which can not only cause fecal leaking, but also can be very difficult to treat. Kegel exercises can improve the tone of the outer sphincter muscle. Cosmetics Shaving, trimming, depilatory, or Brazilian waxing can clear the perineum of hair. Anal bleaching is a process where the perineum, which darkens over the years, is lightened for a more youthful appearance. Anal piercing is among the more extreme piercings and usually interferes with the function of the anus. Pathology Diseases of the anus include anal cancer, abscess, warts, fistula, anal fissure, itching and hemorrhoid. The anus is also a frequent site of sexually transmitted infections. These benefit from medical intervention. Birth defects of the anus include stenosis and imperforation. These benefit from surgical intervention. Damaged anal sphincter (patulous anus in more severe cases) — caused by careless or sometimes necessarily sacrificial surgery in the perineal region or by rough/abrupt penetration in anal sex — can lead to flatus and/or fecal incontinence, chronic constipation and, ultimately, megacolon. In psychology the Freudian term anal fixation is used. Hepatology Hepatology is the branch of medicine that incorporates study of liver, gallbladder, biliary tree and pancreas as well as management of their disorders. Etymologically the word Hepatology is formed of ancient Greek hepar or hepato- meaning ' liver' and suffix -logia meaning 'word' or 'speech'. Although traditionally considered a sub-specialty of gastroenterology, rapid expansion has led in some countries to doctors specializing solely on this area, who are called hepatologists. Diseases and complications related to viral hepatitis and alcohol are the main reason for seeking specialist advice. One third of world population has been infected with Hepatitis B virus at some point in their life. Although most of them would clear the virus from the body, approximately 350 million have become persistent carriers. Up to 80% of liver cancers can be attributed to either hepatitis B or Hepatitis C virus. In terms of number of mortality, the former is second only to smoking among known agents causing cancer. Hopefully, widespread implementation of vaccination and strict screening before blood transfusion are going to lower the infection rate in future. However in many countries overall alcohol intake is on the rise and as one can expect, number of people with cirrhosis and other related complications are increasing. Scope of the specialty As for many medical specialties, patients are most likely to be referred by family physicians( i.e. GP) or by doctors from different disciplines. The reasons might be:
History Evidence from autopsies on Egyptian mummies suggest that liver damage from parasitic infection Bilharziasis was widespread in the ancient society. It is possible that Greeks might be aware of liver's ability to exponentially duplicate as illustrated by Prometheus story. However knowledge about liver diseases in antiquity was some what sketchy. Most of the important advances in the field were made in last 50 years.
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Simply put,
Gastroenterologists that have
accumulated a certain amount of points qualified for the list. This does not
mean that Gastroenterologists that did not accumulate enough points are not good health
care professionals; they merely did not qualify for this list because of the points needed for
qualification.
Choosing
a Gastroenterologist is an important decision. Thus, our goal is to assist you in
making that decision.
In 1805 Philip Bozzini made first attempt to observe living human body through a tube he named Lichtleiter (light guiding instrument) to examine the urinary tract, the rectum and the pharynx. This is the earliest description of
endoscopy.
The pancreas is a gland organ in the digestive and endocrine systems of vertebrates.
It is both exocrine (secreting pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including insulin, glucagon, and somatostatin).
The liver is an organ present in vertebrates and some other animals. It plays a major role in metabolism and has a number of functions in the body, including glycogen storage, plasma protein synthesis, and detoxification. This organ also is the largest gland in the human body. It lies below the diaphragm in the thoracic region of the
abdomen. It produces bile, an alkaline compound which aids in digestion, via the emulsification of lipids. It also performs and regulates a wide variety of high-volume biochemical reactions requiring specialized tissues.
The gallbladder (or
cholecyst, sometimes gall bladder) is a pear-shaped organ that stores about 50 ml of bile (or "gall") until the body needs it for digestion.
The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long. At its commencement its caliber is similar to that of the sigmoid colon, but near its termination it is dilated, forming the rectal ampulla.
