Back to Top | Back One Page

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:

Experience: 

        Each year the Gastroenterologist has been in practice

Training:

        Education and Continuing Education

Professional Associations:

        Member of Professional Medical Associations

Board Certification:

        Completing an approved residency program and passing a
        rigid examination on that specialty

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.

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


Choosing a Gastroenterologist is an important decision. Thus, our goal is to assist you in making that decision.

First of all, when selecting a Gastroenterologist, you may want to begin your search several different ways:

 

Ask family, friends, neighbors and/or co-workers.
Contact your local Chamber of Commerce or Better Business Bureau for reputable physicians that specialize in the areas of medicine that you have a need for.
Contact your city, county or state medical agencies for names of qualified Gastroenterologists. Contact and ask for referrals from medical associations. Many are listed in this publication.
Ask your family doctor. They are in constant contact with all kinds of health care professionals and will be able to provide you with recommendations.

We recommend that you interview the Gastroenterologist and ask the following:

How long have you been in practice?

Is your staff friendly and accommodating?

What are the procedures if we need a doctor in the middle of the night or on a weekend?

Do you have an associate that covers for you when you are not available?

Do you have more than one office and if so, how is your time divided between offices?

What kind of continuing education do you utilize?

Do you accept phone calls during office hours?

How do you stay current on the latest drug prescriptions available and medical testaments?

What types of insurance coverage do you accept?

How do you handle billing? Do you require payment at the time of visit?

Discuss your family medical history and particular problems you are concerned about.

After you have consulted a few Gastroenterologists you should have a good idea which one you felt most comfortable with and best answered your questions.

 


What is Gastroenterology?
from Wikipedia


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:

       Italian Lazzaro Spallanzani (1729–99) was among early physicians to disregard Galen's theories, and in 1780 he gave experimental proof on the action of gastric juice on foodstuffs.
In 1767, German Johann Zimmermann wrote an important work on dysentery.
In 1777 Maximilian de Stoll of Vienna described cancer of the gallbladder.

19th century:

       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.
Charles Emile Troisier described enlargement of lymph node in abdominal cancer.
In 1868 Adolf Kussmaul, a well known German physician, developed the gastroscope. He perfected the technique on sword swallower.
In 1871, at the society of physicians in Vienna, Carl Stoerk demonstrated an esophagoscope made of two telescopic metal tubes, initially devised by Waldenburg in 1870.
In 1876 Karl Wilhelm von Kupffer described the properties of some liver cells now called Kupffer cell.
In 1884 Kronecker and Meltzern studied oesophageal manometry in man.

20th century:

       Rudolph Schindler described many important diseases involving digestive system during World War I in his illustrated textbook and is portrayed by some as the "father of gastroscopy". He and Wolf developed a semiflexible gastroscope in 1932.
In 1932 Burrill Bernard Crohn described Crohn's disease.
In 1957 Basil Hirschowitz introduced the first prototype fibreoptic gastroscope.
In 2005 Barry Marshall and Robin Warren of Australia were awarded the Nobel Prize in Physiology or Medicine for their discovery of Helicobacter pylori (1982/1983) and its role in peptic ulcer disease.

 


Anatomical Range of Gastroenterology

The Salivary Gland


The salivary glands in mammals are exocrine glands that produce saliva. In other taxa such as insects, salivary glands are often used to produce biologically important proteins such as silk or glues. Salivary glands have proven to be very useful to students of genetics due to the occurrence of polytene chromosomes that are common in the salivary gland cells of many Diptera.

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:

       1. Serous cells, which are pyramidal in shape and are joined to usually form a spherical mass of cells called acinus, with a small lumen in the centre. Serous demilunes are found in the submandibular gland.
2. Mucous cells are usually cuboid in shape and organised as tubules, consisting of cylindrical arrays of secretory cells surrounding a lumen. These cells produce glycoproteins that are used for the moistening and lubricating functions of saliva.
3. Myoepithelial cells surround each secretory portion and are able to contract to accelerate secretion of the saliva.

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.

       Parasympathetic innervation to the salivary glands is carried via cranial nerves. The parotid gland receives its parasympathetic input from the glossopharyngeal nerve (CN IX) via the otic ganglion, while the submandibular and sublingual glands receive their parasympathetic input from the facial nerve via the submandibular ganglion.
Direct sympathetic innervation of the salivary glands takes place via preganglionic nerves in the thoracic segments T1-T3 which synapse in the superior cervical ganglion with postganglionic neurons that release norepinephrine, which is then received by ß-adrenergic receptors on the acinar and ductal cells of the salivary glands, leading to an increase in cyclic adenosine monophosphate (cAMP) levels and the corresponding increase of saliva secretion. Note that in this regard both parasympathetic and sympathetic stimuli result in an increase in salivary gland secretions. The sympathetic nervous system also affects salivary gland secretions indirectly by innervating the blood vessels that supply the glands.

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


The esophagus (also spelled oesophagus/śsophagus), or gullet is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. The esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra.

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).

The esophagus is lined with mucous membrane, and is more deeply lined with muscle that acts with peristaltic action to move swallowed food down to the stomach.

Histology

The layers of the esophagus are as follows:

Mucosa
nonkeratinized stratified squamous epithelium: is rapidly turned over, and serves a protective effect due to the high volume transit of food, saliva and mucous.
lamina propria: sparse.
muscularis mucosae: smooth muscle
Submucosa: Contains the mucous secreting glands (esophageal glands), and connective structures  termed papillae.
Muscularis Externa (or "muscularis propria"): composition varies in different parts of the esophagus, to correspond with the conscious control over swallowing in the upper portions and the autonomic control in the lower portions:
Upper Third, or superior part: striated muscle
Middle Third, smooth muscle and striated muscle,
Inferior Third: predominantly smooth muscle.
       Adventitia

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.

Esophageal diseases and conditions

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


In anatomy, the stomach is a bean-shaped hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. The word stomach is derived from the Latin stomachus. The words gastro- and gastric (meaning related to the stomach) are both derived from the Greek word gaster.

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

The stomach lies between the esophagus and the duodenum (the first part of the small intestine). It is on the left side of the abdominal cavity. The top of the stomach lies against the diaphragm. Lying beneath the stomach is the pancreas, and the greater omentum which hangs from the greater curvature.

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:

       Cardia: Where the contents of the esophagus empty into the stomach.
Fundus: Formed by the upper curvature of the organ.
Body or corpus: The main, central region.
Pylorus or antrum: The lower section of the organ that facilitates emptying the contents into the small intestine.

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:

       mucosa: The first main layer. This consists of an epithelium, the lamina propria underneath, and a thin layer of smooth muscle called the muscularis mucosae.
submucosa: This layer lies under the mucosa and consists of fibrous connective tissue, separating the mucosa from the next layer. The Meissner's plexus is in this layer.
muscularis externa: Under the submucosa, the muscularis externa in the stomach differs from that of other GI organs in that it has three layers of smooth muscle instead of two.
inner oblique layer: This layer is responsible for creating the motion that churns and physically breaks down the food. It is the only layer of the three which is not seen in other parts of the digestive system. The antrum has thicker skin cells in its walls and performs more forceful contractions than the fundus.
middle circular layer: At this layer, the pylorus is surrounded by a thick circular muscular wall which is normally tonically constricted forming a functional (if not anatomically discrete) pyloric sphincter, which controls the movement of chyme into the duodenum. This layer is concentric to the longitudinal axis of the stomach.
outer longituditinal layer: Auerbach's plexus is found between this layer and the middle circular layer.
serosa: This layer is under the muscularis externa, consisting of layers of connective tissue continuous with the peritoneum.

 Glands

The epithelium of the stomach forms deep pits. The glands at these locations are named for the corresponding part of the stomach:

Cardiac glands
(at cardia)

Pyloric glands
(at pylorus)

Fundic glands
(at fundus)

(click for larger images)

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:

       Gastrin The hormone gastrin causes an increase in the secretion of HCl, pepsinogen and intrinsic factor from parietal cells in the stomach. It also causes increased motility in the stomach. Gastrin is released by G-cells in the stomach to distention of the antrum, and digestive products. It is inhibited by a pH normally less than 4 (high acid), as well as the hormone somatostatin.
Cholecystokinin Cholecystokinin (CCK) has most effect on the gall bladder, but it also decreases gastric emptying.
Secretin In a different and rare manner, secretin, produced in the small intestine, has most effects on the pancreas, but will also diminish acid secretion in the stomach.
Gastric inhibitory peptide Gastric inhibitory peptide (GIP) decreases both gastric acid and motility.
Enteroglucagon enteroglucagon decreases both gastric acid and motility.

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

               Dyspepsia
Stomach ache
Peptic ulcer
Achlorhydria
Hypochlorhydria
Linitis plastica
Zollinger-Ellison syndrome
Gastroparesis
GERD
Borborygmus

Historically, it was widely believed that the highly acidic environment of the stomach would keep the stomach immune from infection. However, a large number of studies have indicated that most cases of stomach ulcers, gastritis, and stomach cancer are caused by Helicobacter pylori infection. One of the ways it is able to survive in the stomach involves its urease enzymes which metabolize urea (which is normally secreted into the stomach) to ammonia and carbon dioxide which neutralizes gastric acid and thus prevents its digestion. In recent years, it has been discovered that other Helicobacter bacteria are also capable of colonizing the stomach and have been associated with gastritis.

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


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).

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 head abuts the second part of the duodenum.
The pancreatic neck springs from the right upper portion of the front of the head.
The body of the pancreas lies at the level of L2 on the spine.
The tail of the pancreas extends towards the spleen.

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:

       the splenic artery supplies the neck, body, and tail of the pancreas.
the superior mesenteric artery provides the inferior pancreaticoduodenal artery
the gastroduodenal artery provides the superior pancreaticoduodenal artery

Venous drainage is via the pancreaticoduodenal veins which end up in the portal vein. The splenic vein passes posterior to the pancreas but is said to not drain the pancreas itself. The portal vein is formed by the union of the superior mesenteric vein and splenic vein posterior to the neck of the pancreas. In some people (some books say 40% of people), the inferior mesenteric vein also joins with the splenic vein behind the pancreas (in others it simply joins with the superior mesenteric vein instead).

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:

 Name of cells   Endocrine product   % of islet cells   Representative function 
beta cells Insulin and Amylin 50-80% lower blood sugar
alpha cells Glucagon 15-20% raise blood sugar
delta cells Somatostatin 3-10% inhibit endocrine pancreas
PP cells Pancreatic polypeptide 1% inhibit exocrine pancreas

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:

 Name of cells   Exocrine secretion   Exocrine secretion 
Centroacinar cells bicarbonate ions Secretin
Basophilic cells  digestive enzymes

(pancreatic amylase, Pancreatic lipase,

trypsinogen, chymotrypsinogen, etc.)

CCK

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:

       Tumors of the centroacinar cells.
Pancreatic Exocrine Tumors. Examples include:
Pancreatic adenocarcinoma. It represents about 95% of all pancreatic tumors. 75% to 96% of all pancreatic adenocarcinomas are ductal cell adenocarcinomas.
Other tumors of the exocrine pancreas, such as serous cystadenomas.
Pancreatic Endocrine Tumors (PET's), also known as Endocrine Pancreatic Tumors (EPT's), or Islet Cell Tumors. They are a type of Neuroendocrine tumors. PET's represent between 1 and 2% of all pancreatic tumors. Between 15 and 30% of all PET's are non-functioning, while 70 to 85% of them are functioning. Examples of functioning PET's include:
Gastrinoma, producing excessive gastrin and causing Zollinger-Ellison Syndrome (ZES)
Insulinoma, producing excessive insulin
Glucagonoma, producing excessive glucagon
Vasoactive intestinal peptideoma (VIPoma), producing excessive vasoactive intestinal peptide (VIP)
PPoma, producing excessive pancreatic polypeptide (often classed with non-functioning PETs)
Somatostatinoma, producing excessive somatostatin
Watery diarrhea, hypokalemia-achlorhydria (WDHA)
CRHoma, producing excessive corticotropin-releasing hormonse (CRH)
Calcitoninoma, producing excessive calcitonin
GHRHoma, producing excessive growth-hormone-releasing hormone (GHRH)
Neurotensinoma, producing excessive neurotensin
ACTHoma, producing excessive adrenocorticotropic hormone (ACTH)
GRFoma, producing excessive growth-hormone release factor (GRF)
Parathyroid hormone–related peptide tumor

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:

       Acute pancreatitis: A rapidly-onset inflammation of the pancreas.
Chronic pancreatitis: A long-standing inflammation of the pancreas.
Hereditary pancreatitis: A genetic abnormality that renders trypsinogen active within the pancreas, which in turn leads to digestion of the pancreas from the inside.

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


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.

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.

Physiology

The various functions of the liver are carried out by the liver cells or hepatocytes.

       The liver produces and excretes bile (a greenish liquid) required for emulsifying fats. Some of the bile drains directly into the duodenum, and some is stored in the gallbladder.
The liver performs several roles in carbohydrate metabolism:
Gluconeogenesis (the synthesis of glucose from certain amino acids, lactate or glycerol)
Glycogenolysis (the breakdown of glycogen into glucose) (muscle tissues can also do this)
Glycogenesis (the formation of glycogen from glucose)
The breakdown of insulin and other hormones
The liver is responsible for the mainstay of protein metabolism.
The liver also performs several roles in lipid metabolism:
Cholesterol synthesis
The production of triglycerides (fats).
The liver produces coagulation factors I (fibrinogen), II (prothrombin), V, VII, IX, X and XI, as well as protein C, protein S and antithrombin.
The liver breaks down hemoglobin, creating metabolites that are added to bile as pigment (bilirubin and biliverdin).
The liver breaks down toxic substances and most medicinal products in a process called drug metabolism. This sometimes results in toxication, when the metabolite is more toxic than its precursor.
The liver converts ammonia to urea.
The liver stores a multitude of substances, including glucose in the form of glycogen, vitamin B12, iron, and copper.
In the first trimester fetus, the liver is the main site of red blood cell production. By the 32nd week of gestation, the bone marrow has almost completely taken over that task.
The liver is responsible for immunological effects- the reticuloendothelial system of the liver contains many immunologically active cells, acting as a 'sieve' for antigens carried to it via the portal system.

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.

       Hepatitis, inflammation of the liver, caused mainly by various viruses but also by some poisons, autoimmunity or hereditary conditions.
Cirrhosis is the formation of fibrous tissue in the liver, replacing dead liver cells. The death of the liver cells can for example be caused by viral hepatitis, alcoholism or contact with other liver-toxic chemicals.
Haemochromatosis, a hereditary disease causing the accumulation of iron in the body, eventually leading to liver damage.
Cancer of the liver (primary hepatocellular carcinoma or cholangiocarcinoma and metastatic cancers, usually from other parts of the gastrointestinal tract).
Wilson's disease, a hereditary disease which causes the body to retain copper.
Primary sclerosing cholangitis, an inflammatory disease of the bile duct, autoimmune in nature.
Primary biliary cirrhosis, autoimmune disease of small bile ducts.
Budd-Chiari syndrome, obstruction of the hepatic vein.
Gilbert's syndrome, a genetic disorder of bilirubin metabolism, found in about 5% of the population.
Glycogen storage disease type II, The build-up of glycogen causes progressive muscle weakness (myopathy) throughout the body and affects various body tissues, particularly in the heart, skeletal muscles, liver and nervous system.

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 transplantation is the only option for those with irreversible liver failure. Most transplants are done for chronic liver diseases leading to cirrhosis, such as chronic hepatitis C, alcoholism, autoimmune hepatitis, and many others. Less commonly, liver transplantation is done for fulminant hepatic failure, in which liver failure occurs over days to weeks.

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


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.

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.

      The cystic duct connects the gallbladder to the common hepatic duct to form the common bile duct.
The common bile duct then joins the pancreatic duct, and enters through the hepatopancreatic ampulla at the major duodenal papilla.

Microscopic anatomy

The different layers of the gallbladder are as follows:

     The gallbladder has a simple columnar epithelial lining characterized by recesses called Aschoff's recesses, which are pouches inside the lining.
Under the epithelium there is a layer of connective tissue (lamina propria).
Beneath the connective tissue is a wall of smooth muscle (muscularis mucosa) that contracts in response to cholecystokinin, a peptide hormone secreted by the duodenum.
There is essentially no submucosa separating the connective tissue from serosa and adventitia.

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

       Cholestasis is the blockage in the supply of bile into the digestive tract. It can be "intrahepatic" (the obstruction is in the liver) or "extrahepatic" (outside the liver). It can lead to jaundice, and is identified by the presence of elevated bilirubin level that is mainly conjugated.
Biliary colic is when a gallstone blocks either the common bile duct or the duct leading into it from the gallbladder.
Up to 25% of all people have gallstones (cholelithiasis), composed of lecithin and bile acids. These can cause abdominal pain, usually in relation with a meal, as the gallbladder contracts and gallstones pass through the bile duct.
Acute or chronic inflammation of the gallbladder (cholecystitis) causes abdominal pain. 90% of cases of acute cholecystitis are caused by the presence of gallstones. The actual inflammation is due to secondary infection with bacteria of an obstructed gallbladder, with the obstruction caused by the gallstone.
When gallstones obstruct the common bile duct (choledocholithiasis), the patient develops jaundice and liver cell damage. It is a medical emergency, requiring endoscopic or surgical treatment such as a cholecystectomy.
A rare clinical entity is ileus (bowel) obstruction by a large gallstone, or gallstone ileus. This condition develops in patients with longstanding gallstone disease, in which the gallbladder forms a fistula with the digestive tract. Large stones pass into the bowel, and generally block the gut at the level of Treitz' ligament or the ileocecal valve, two narrow points in the digestive tract. The treatment is surgical.
Cancer of the gallbladder is a rare but highly fatal disease. It has been associated with gallstone disease, estrogens, cigarette smoking, alcohol consumption and obesity. Despite aggressive modern surgical approaches, advanced imaging techniques, and endoscopy, nearly 90% of patients die from advanced stages of the disease and experience pain, jaundice, weight loss, and ascites.
Polyps (growths) are sometimes detected during diagnostic tests for gallbladder disease. Small gallbladder polyps (up to 10 mm) pose little or no risk, but large ones (greater than 15 mm) pose some risk for cancer, so the gallbladder should be removed. Patients with polyps 10 mm to 15 mm have a lower risk but they should still discuss removal of their gallbladder with their physician. Of special note is a condition called primary sclerosing cholangitis, which causes inflammation and scarring in the bile duct. It is associated with a lifetime risk of 7% to 12% for gallbladder cancer. The cause is unknown, although primary sclerosing cholangitis tends to strike younger men who have ulcerative colitis. Polyps are often detected in this condition and have a very high likelihood of malignancy.

 


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 intestinal tract can be broadly divided into two different parts, the small and large intestine. Grayish-purple in color and about 35 mm (1.5 inches) in diameter, the small intestine is the first and longest, measuring 6-8 meters (22-25 feet) on average in an adult man. Shorter and relatively stockier, the large intestine is a dark reddish color, measuring roughly 1.5 meters (5 feet) on average. Both intestines share a general structure with the whole gut, and is composed of several layers. The lumen is the cavity where digested material passes through and from where nutrients are absorbed. Along the whole length of the gut in the glandular epithelium are goblet cells. These secrete mucus which lubricates the passage of food along and protects it from digestive enzymes. Villi are vaginations of the mucosa and increase the overall surface area of the intestine while also containing a lacteal, which is connected to the lymph system and aids in the removal of lipids and tissue fluid from the blood supply. Micro villi are present on the epithelium of a villus and further increase the surface area over which absorption can take place. Small intestine s as much as 20ft. long.

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

       Gastroenteritis is inflammation of the intestines and is the most common disease of the intestines. It can arise as the result of food poisoning.
Ileus is a blockage of the intestines.
Ileitis is an inflammation of the ileum.
Colitis is an inflammation of the large intestine.
Appendicitis is inflammation of the vermiform appendix located at the cecum. This is a potentially fatal disease if left untreated; most cases of appendicitis require surgical intervention.
Coeliac disease is a common form of malabsorption, affecting up to 1% of people of northern European descent. Allergy to gluten proteins, found in wheat, barley and rye, causes villous atrophy in the small intestine. Life-long dietary avoidance of these foodstuffs in a gluten-free diet is the only treatment.
Crohn's disease and ulcerative colitis are examples of inflammatory bowel disease. While Crohn's can affect the entire gastrointestinal tract, ulcerative colitis is limited to the large intestine. Crohn's disease is widely regarded as an autoimmune disease. Although ulcerative colitis is often treated as though it were an autoimmune disease, there is no consensus that it actually is such. (See List of autoimmune diseases).
Enteroviruses are named by their transmission-route through the intestine (enteric = related to intestine), but their symptoms aren't mainly associated with the intestine.

Disorders

       Irritable bowel syndrome (IBS) is the most common functional disorder of the intestine. Functional constipation and chronic functional abdominal pain are other disorders of the intestine that have physiological causes, but do not have identifiable structural, chemical, or infectious pathologies. They are aberrations of normal bowel function but not diseases.
Diverticular disease is a condition that is very common in older people in industrialized countries. It usually affects the large intestine but has been known to affect the small intestine as well. Diverticular disease occurs when pouches form on the intestinal wall. Once the pouches become inflamed it is known as Diverticulitis, or Diverticular disease.
Endometriosis can affect the intestines, with similar symptoms to IBS.
Bowel twist (or similarly, bowel strangulation) is a comparatively rare event (usually developing sometime after major bowel surgery). It is, however, hard to diagnose correctly, and if left uncorrected can lead to bowel infarction and death. (The singer Maurice Gibb is understood to have died from this.)

The Rectum


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.

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:

       (1) Rectal temperature is the closest to core body temperature and in children that young, accuracy is critical.
(2) Younger children are unable to cooperate when having their temperature taken by mouth (oral) which is recommended for children, ages 6 and above and for adults.

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


In anatomy, the anus (from Latin a-nus "ring, anus") is the external opening of the rectum. Closure is controlled by sphincter muscles. Feces are expelled from the body through the anus during the act of defecation, which is the primary function of the anus. Most animals — from simple worms to elephants and humans — have a tubular gut, with a mouth at one end and an anus at the other.

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

Intra-rectal pressure builds as the rectum fills with feces, pushing the feces against the walls of the anal canal. Contractions of abdominal and pelvic floor muscles can create intra-abdominal pressure which further increases intra-rectal pressure. The internal anal sphincter (an involuntary muscle) responds to the pressure by relaxing, thus allowing the feces to enter the canal. The rectum shortens as feces are pushed into the anal canal and peristaltic waves push the feces out of the rectum. Relaxation of the internal and external anal sphincters allows the feces to exit from the anus, finally, as the levator ani muscles pull the anus up over the exiting feces.

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:

       Jaundice
Gastrointestinal bleeding from portal hypertension related to liver damage
Abnormal blood test suggesting liver disease
Enzyme defects leading to bigger liver in children commonly named storage disease of liver
Hepatitis virus positivity in blood, perhaps discovered on screening blood tests
Ascites or swelling of abdomen from fluid accumulation, commonly due to liver disease but can be from other diseases like heart failure
All patients with advanced liver disease e.g. cirrhosis should be under specialist care
To undergo ERCP for diagnosing diseases of biliary tree or their management
Fever with other features suggestive of infection involving mentioned organs. Some exotic tropical diseases like hydatid cyst, kala-azar or schistosomiasis may be suspected. Microbiologists would be involved as well
Damage to liver from other toxins like drugs. Paracetamol overdose is common
Systemic diseases affecting liver and biliary tree e.g. Haemochromatosis
Follow up of liver transplant
Pancreatitis - commonly due to alcohol or gall stone
Cancer of above organs. Usually multi-disciplinary approach is under taken with involvement of oncologist and other experts.

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.

       In 400 BC Hippocrates mentioned liver abscess in apporium.
Roman anatomist Galen thought liver is the principle organ of the body. He also identified its relationship with gallbladder and spleen.
Around 100CE Areteus of Cappadoca wrote on jaundice
In medieval period Avicenna noted the importance of urine in diagnosing liver conditions.
1770 French anatomist Antoine Portal, noted bleeding due to esophageal varices
1844 Gabriel Valentin showed pancreatic juices break down food in digestion.
1846 Justus Von Leibig discovered pancreatic juice tyrosine
1862 Austin Flint described the production of "stercorin".
1875 Victor Charles Hanot described cirrhotic jaundice and other diseases of liver
In 1958, Moore developed a standard technique for canine orthotopic liver transplantation.
The first human liver transplant was performed on a 3-year-old male afflicted with biliary atresia in 1963 by Dr. Thomas E. Starzl after perfecting the technique on canine livers.
Baruch S. Blumberg discovered Hepatitis B virus in 1966 and developed the first vaccine against it 1969. He was awarded the Nobel Prize in Physiology or Medicine 1976.


Contact Us     ||     CRC Home Page     ||     Top Gastroenterologists Search Engine

Copyright © Consumers' Research Council of America. All rights reserved.