pediagenosis: Digestive
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Showing posts with label Digestive. Show all posts
Showing posts with label Digestive. Show all posts

Tuesday, September 21, 2021

Motility of Small Intestine

Motility of Small Intestine

Motility of Small Intestine

MOTILITY AND DYSMOTILITY OF SMALL INTESTINE
MOTILITY AND DYSMOTILITY OF SMALL INTESTINE


The digestive status (fed versus fasting) is a key component of small bowel motility. Fasting small intestinal motility follows four cyclic phases, referred to as the migratory motor complex. The migratory motor complex consists of waves of electrical activity that sweep through the intestine every 90 to 120 minutes. In addition to facilitating the transport of indigestible substances from the stomach to the colon, the migratory motor complex also transports bacteria from the small intestine to the large intestine and inhibits the reflux of colonic bacteria to the terminal ileum. It has thereby been termed the “intestinal housekeeper.”

Lymph Drainage of Small Intestine

Lymph Drainage of Small Intestine

Lymph Drainage of Small Intestine

Lymph Drainage of Small Intestine


The lymph vessels of the small intestine begin with the central lacteals of the villi. At the base of the villi, each central lacteal joins with lymph capillaries, draining the nearby intestinal crypts. These lymph capillaries form a fine network within the lamina propria, in which the first lymphatic valves are already encountered. Many minute branches emerge from this network, penetrating through the muscularis mucosae into the submucosa, which hosts a sizable network of lymphatic vessels. The vessels of this network have conspicuous valves that prevent retrograde motion of the lymphatic fluid once it is inside the vessels. Progressively larger lymph vessels, receiving additional lymph from the layers of the muscularis mucosae and from the serosa and subserosa, pass toward the attachment of the mesentery to the small intestine. Within the mesentery, the lymph vessels travel alongside arteries and veins. These larger lymph vessels have been referred to as chyliferous vessels or lacteals because they transport emulsified fat absorbed from the intestines and appear as milky-white threads after the ingestion of fat-containing food. Lymph fluid traveling through these vessels encounters several juxtaintestinal (within the mesentery, alongside the intestines) superior mesenteric lymph nodes, which number some 100 to 200 and constitute the largest aggregate of lymph nodes in the body. They increase in number and size toward the root of the mesentery. In the root of the mesentery, larger lymphatic branches are situated, which lead into the central group of superior mesenteric nodes in the area where the superior mesenteric artery arises from the aorta.

Blood Supply of Small Intestine

Blood Supply of Small Intestine

Blood Supply of Small Intestine

Blood Supply of Small Intestine


For the typical pattern of arterial branching of the small intestines, please refer to Plates 1-1 and 1-2. In this section, we will describe the variations concerning the origin, course, anastomoses, and distribution of the vessels supplying the small intestine. These variations are so frequent that conventional textbook descriptions are inadequate for anyone attempting procedures in the area. Typically, the superior mesenteric artery supplies almost all of the small intestine aside from the proximal duodenum, which receives blood from the supraduodenal and superior pancreaticoduodenal arteries. These arteries are branches of the gastroduodenal artery, a branch of the common hepatic artery, which is itself a branch of the celiac trunk.

Structure of Small Intestine

Structure of Small Intestine

Structure of Small Intestine

MUCOSA AND MUSCULATURE OF DUODENUM
MUCOSA AND MUSCULATURE OF DUODENUM


The freely mobile portion of the small intestine, which is attached to the mesentery, extends from the duodenojejunal flexure to the ileocolic orifice, where the small intestine joins the large intestine. This portion of the small intestine consists of the jejunum and the ileum. They run imperceptibly into each other, the transition being marked by a gradual change in the diameter of the lumen and by several structural alterations.

Topography and Relations of Small Bowel

Topography and Relations of Small Bowel

Topography and Relations of Small Bowel

Topography and Relations of Small Bowel


The small intestine consists of a retroperitoneal portion, the duodenum, and a mesenteric portion made up of the coils of the jejunum and ileum. The total length of the mesenteric portion of the small intestine varies considerably. The average for adults is roughly 5 m. The proximal jejunum forms approximately two fifths of the mesenteric portion, and the ileum forms the remaining three fifths. The jejunum commences at the duodenojejunal flexure on the left side of the second lumbar vertebra or, occasionally, somewhat more cranially. The ileum terminates when it joins the large intestine in the right iliac fossa. Although the division between the jejunum and ileum is not grossly visible (the appearance of the arteries and histologic structure can be used to distinguish the two regions), the coils of the jejunum tend to be on the superior left side of the abdomen and those of the ileum on the inferior right side.

Development of Small Intestine

Development of Small Intestine

Development of Small Intestine

Development of Small Intestine


The small intestine includes the duodenum, jejunum, and ileum. During development of the gastrointestinal system, the duodenum comes from the distal portion of the foregut, whereas the jejunum and ileum come entirely from the midgut. The duodenum moves to the right of the midline as the stomach rotates and shifts to the left side of the abdomen during weeks 4 to 6 of fetal life. As development proceeds, the common bile duct moves to the posterior side of the gut tube as the stomach rotates and the liver enlarges. One aspect of duodenal development that is clinically important is that during weeks 5 and 6, the epithelial lining of the duodenum, derived from the endoderm, proliferates to the point that it completely blocks the lumen of the duodenum. However, the lumen of the duodenum typically recanalizes so that the fetus can begin swallowing amniotic fluid. If the lumen of the duodenum does not recanalize or opens incompletely, duodenal atresia or stenosis will occur. As a region of gut that links the foregut and midgut, the duodenum is supplied by branches of both the celiac and superior mesenteric arteries. The descending and horizontal portions of the duodenum are the regions where this anastomosis occurs, and these are also the regions in which atresia or stenosis is most likely to be manifested.

Physiology of Gastroenteric Stomas

Physiology of Gastroenteric Stomas

Physiology of Gastroenteric Stomas

Physiology of Gastroenteric Stomas


Creation of a well-constructed ostomy by a highly skilled surgeon at the site of an anastomosis or as a cutaneous stoma that preserves normal digestive functions can result in an excellent quality of life for a patient undergoing resection of portions of the digestive system. Technical risks associated with the creation of any stoma include anastomotic leak, dehiscence, and stricture. The size of the anastomosis varies with the organs involved and the desired outcome of the procedure, but it is important to note that while stricture-related closure is always a risk, larger stomas are not always better. Cutaneous ostomies have an additional risk of prolapse, bleeding, and peristomal ulceration. Evaluation of ostomy function and anatomy may require skilled radiologic assessment with barium studies, CT studies, or endoscopy, or a combination of these studies. Endoscopic evaluation also provides the potential for therapeutic interventions to correct stomal problems, including dilatation and placement of self-expanding stents.

Abdominal Wounds: Blast Injuries

Abdominal Wounds: Blast Injuries

Abdominal Wounds: Blast Injuries

Abdominal Wounds: Blast Injuries


Abdominal wounds and blunt trauma are common acute injuries encountered in emergency settings. The depth and severity of a penetrating wound cannot be determined by history or physical examination alone. After stabilizing the airway, breathing and circulation, emergency cross-sectional imaging is essential as the operating room is being prepared and surgical expertise recruited. Broad-spectrum intravenous antibiotics should be hung on admission as the patient is prepped for operation. If extensive intraabdominal bleeding is occurring, laparotomy should be done as early as possible. Exploration must be thorough, and all perforations must be closed. Diversion of the fecal stream is often advised when there has been peritoneal soiling. In extensive damage, resection is necessary. In addition to customary preoperative and postoperative measures, oxygen, continuous gastroduodenal suction, multiple drains, and broad-spectrum antibiotic therapy are essential.

Cancer of Peritoneum

Cancer of Peritoneum

Cancer of Peritoneum

Cancer of Peritoneum


Primary malignant tumors of the peritoneum (meso-theliomas or endotheliomas) are rare, but secondary malignant tumors are relatively common. Tumor cell spread into the peritoneum occurs by direct extension, hematogenous spread, or lymphatic spread. Once the peritoneum has been invaded, dissemination of malignant cells throughout the peritoneal cavity and implantation diffusely throughout the peritoneal surfaces can occur rapidly. Epithelial primary carcinomas commonly metastasize to the peritoneum (e.g., adenocarcinomas of the stomach, intestine, ovaries, and, less commonly, lung and breast). Melanomas also frequently metastasize to the digestive system, including the mesentery. Malignant neoplasms of the retroperitoneal connective, nervous, or muscular tissue, as well as sarcomas and teratomas, although rare, invade the peritoneum or become metastasized within it.

Chronic Peritonitis

Chronic Peritonitis

Chronic Peritonitis

Chronic Peritonitis


Tuberculous peritonitis can occur at any age but is seen more commonly in young adults and children, patients undergoing dialysis, or immunocompromised patients such as those with acquired immunodeficiency syndrome. It is practically always secondary to some other focus in the body, the most frequent sources of infection being tuberculous lesions in the bowel, mesenteric glands, and fallopian tubes. In the course of general miliary tuberculosis, the tuberculous peritonitis may occur as an acute infection; much more commonly, however, it appears as a chronic condition that manifests itself in one of two main forms: (1) exudative or moist and (2) plastic or dry. In the first variety, the exudation is marked and the abdominal cavity becomes filled with a thin ascitic fluid; numerous tubercles, about the size of a pinhead or larger, appear on the peritoneal surfaces. In the second variety, the exudate is dense and rich in fibrin, formation of adhesions occurs most readily, and the viscera become matted together; the peritoneum is studded with tubercles, which, however, may be covered by deposits of fibrin; the omentum is often greatly thickened and rolled up. Caseous necrosis of tuberculous lesions may lead to formation of fistulous tracts. The two varieties may occur together, giving rise to the so-called encysted or encapsulated form characterized by loculated collections of fluid encysted by the dense adhesions.

Friday, June 11, 2021

The “Acute Abdomen”

The “Acute Abdomen”

The “Acute Abdomen”

CAUSES OF ACUTE ABDOMEN
CAUSES OF ACUTE ABDOMEN


An acute abdominal condition should be described as acute abdomen when a patient complains of abdominal pain that persists for more than a few hours and is associated with tenderness or other evidence of an inflammatory reaction or a visceral dysfunction. The diagnosis of the cause of acute abdominal conditions remains one of the most challenging problems in medicine. Many pathologic processes, both intraabdominal and extra-abdominal, may result in an acute abdomen. An accurate history, thorough physical examination, and proper laboratory examinations help to make the broad differential diagnosis of causes.

Overview of Digestive Tract Obstructions

Overview of Digestive Tract Obstructions

Overview of Digestive Tract Obstructions

Overview of Digestive Tract Obstructions


Any organic or functional condition that primarily or indirectly impedes the normal propulsion of luminal contents from the esophagus to the anus could be considered a partial or complete obstruction. In the newborn, a variety of congenital anomalies (esophageal, intestinal, anal atresias, colonic malrotation, volvulus of the midgut, meconium ileus, aganglionic megacolon) resulting in obstruction are illustrated here. Other causes of mechanical interference of intestinal function in early infancy include incarceration in an internal or external (inguinal) hernia, congenital peritoneal bands, intestinal duplications, volvulus due to mesenteric cysts, and annular pancreas, though the latter may not become clinically manifested until the patient is an adult or an aged adult.

Laparoscopic Peritoneoscopy

Laparoscopic Peritoneoscopy

Laparoscopic Peritoneoscopy

Laparoscopic Peritoneoscopy


Laparoscopic peritoneoscopy is the direct inspection of the peritoneal cavity and its contents by means of an endoscopic instrument introduced through the abdominal wall. Laparoscopic surgery has revolutionized the field of surgery and has gradually been replacing many conventional surgical procedures. The procedure is used in gastroenterologic, general surgical, and gynecologic disorders in which a positive diagnosis cannot be established by simpler methods. Its value lies in the fact that it can frequently supply information that otherwise would be obtained only by exploratory laparotomy. In addition to being a surgical method, it is particularly valuable as a diagnostic tool for visualizing and obtaining biopsies from peritoneal surfaces, the liver, the omentum, and the small bowel, as well as the pelvic organs. Intraabdominal adhesions, peritoneal carcinomatosis or tuberculosis, ascites, or hemorrhage can readily be recognized and sampled via a laparo- scope. In malignant disease, laparoscopy is useful for staging.

Overview of Gastrointestinal Hemorrhage

Overview of Gastrointestinal Hemorrhage

Overview of Gastrointestinal Hemorrhage

CAUSES OF GASTROINTESTINAL HEMORRHAGE
CAUSES OF GASTROINTESTINAL HEMORRHAGE


Many gastrointestinal disorders manifest themselves by bleeding. Intestinal bleeding may present as bright-red blood, suggesting gross lower bleeding (hematochezia), passage of black stool (melena), or other findings of bleeding but no change in stool color (occult bleeding). When no cause of bleeding can be detected with the usual examinations, obscure gastrointestinal bleeding is occurring.

Secretory, Digestive, and Absorptive Functions of Small and Large Intestines

Secretory, Digestive, and Absorptive Functions of Small and Large Intestines

Secretory, Digestive, and Absorptive Functions of Small and Large Intestines

DIGESTION OF PROTEIN
DIGESTION OF PROTEIN


The purpose of the complex enzymatic reactions to which foodstuffs are exposed within the intestinal lumen is to prepare nutrients for transfer into and assimilation within the organism. The lumen of the digestive system, which is the space encompassed by the wall of the digestive tube, belongs, fundamentally speaking, to the outside world, and the processes by which the products of digestion enter and pass through the intestinal wall into the circulation are called secretion and absorption, respectively. The mucosa of the small intestine throughout its length is lined by cells involved with both secretion and absorption: mucus-secreting cells, neuroendocrine cells, and immune active cells. The incredible efficiency of intestinal function is emphasized by the fact that of the approximately 8 L of fluid that enters the small intestine, only 100 to 200 mL is excreted from the rectum, for an efficiency rate in excess of 98%. In disease states, the large and small intestines absorb even more fluid, sometimes exceeding 25 L per day. Alternatively, in secretory dis- orders and infection, the volume of diarrhea lost may rapidly pose a life-threatening risk of dehydration, with the loss of many liters of fluids and their accompanying electrolytes.

Sunday, March 7, 2021

BARIATRIC SURGERY

BARIATRIC SURGERY

BARIATRIC SURGERY

Obesity is associated with a decrease in the quality of life as well as the life expectancy. Although both medical therapy and caloric reduction remain the first-line therapies for obesity, bariatric surgery is the most effective therapy for sustained weight loss. Bariatric surgery is considered for people with a body mass index greater than 40 kg/m2, or for those with a body mass index less than 40 kg/m2 and obesity-related diseases. Bariatric surgery involves surgical manipulation of the gastrointestinal tract to alter normal anatomy and physiology to accomplish weight loss. Weight loss has been described through two mechanisms: restriction of food intake and malabsorption of ingested food. Additionally, the neurohormonal effects of bariatric surgery are now recognized as an important mechanism for both weight loss and improvement in comorbid conditions. Along with weight loss, bariatric surgery can improve comorbidities, including diabetes mellitus, hypertension, hyperlipidemia, obstructive sleep apnea, and GERD. Relative contraindications include poorly managed psychiatric disease, a history of eating disorders, poor compliance with dietary modifications, or high concern about the patient’s ability to comply with medical follow-up.

PRINCIPLES OF OPERATIVE PROCEDURES

PRINCIPLES OF OPERATIVE PROCEDURES

PRINCIPLES OF OPERATIVE PROCEDURES

Treatment of a peptic, gastric, or duodenal ulcer begins with medical management (diet, antacid therapy, anti-secretory drugs). No rule of thumb can be given or used to fix the period of time during which medical treatment should be continued in the hope of improvement in symptoms. A great variety of individual factors must be considered before concluding that further medical efforts to regulate diet, habits, and gastric secretion will not be helpful. In general, however, the physician and patient should avail themselves of the benefit of consultation with the surgeon if the symptoms do not abate after several months of adhering strictly to sound medical therapy. Failure of response with a well-planned regimen, repeated recurrences of severe symptoms, intractable ulcer pain, lack of endoscopic evidence that the ulcer has not completely healed after a few months (even though marked subjective improvement is noted), persistence of blood in the stool, and any other signs of a threatening complication are fairly universally accepted as indications for surgical intervention.

CARCINOMA OF STOMACH

CARCINOMA OF STOMACH

CARCINOMA OF STOMACH

Gastric cancer affects more than 22,000 Americans yearly. Cancer of the stomach is seen more than twice as often in men as in women. It is essentially a disease of middle and old age, about 85% of cases arising after the age of 40. Gastric cancer was previously the most common malignant neoplasm causing death in the male population, but today its incidence has slowly decreased, to between 16% and 25%. The increased incidences of lung carcinoma and esophageal cancer, primarily esophageal adenocarcinoma, have now caused these cancers to become the leading malignant causes of death in men. In women, cancers of the uterus and of the breast are more frequent than of the stomach.

HEALING OF GASTRIC ULCER

HEALING OF GASTRIC ULCER

HEALING OF GASTRIC ULCER

In most cases, gastric ulcers heal without complications. Inflammation and edema of the ulcer wall subside. As a result, the wall tends to become flattened. The fibrinopurulent exudate on the floor of the ulcer separates off, is discarded, and is replaced by healthy granulation tissue and, subsequently, fibrous tissue. The size and depth of the ulcer are reduced, chiefly by cicatrization (a process of wound healing that produces scar tissue) and the contraction of the fibroblasts on the floor and in the wall of the lesion. In addition, the epithelium grows inward from each margin to cover the area of ulceration. From this epithelial layer, projections down-ward eventually develop, forming simple glands. Finally, the entire area is covered by epithelium. As the contraction of the fibrous tissue progresses, a permanent scar and, in some cases, radiation of the mucosal folds develop. During the healing process the ends of the muscular coat may fuse with the muscularis mucosae. But, although severed ends of the muscular layer approximate one another as a result of the cicatrizing process, restitution of a muscular breach is never complete. This remains as permanent evidence of the original lesion. Puckering and radiating streaks on the serosal surface are further evidence of the scar produced in the healing process of the chronic gastric ulcer. This can be seen endoscopically, as medical practice suggests following these ulcers until healing occurs. The healing of a chronic gastric ulcer sometimes is complete, but not infrequently such ulcers are prone to recur, particularly if the newly formed mucous membrane is thin and its vascular supply deficient. In other cases the recurrence of ulcer symptoms is due to an entirely new ulcer, the scar of the original lesion remaining permanent.

COMPLICATIONS OF GASTRIC AND DUODENAL ULCERS

COMPLICATIONS OF GASTRIC AND DUODENAL ULCERS

COMPLICATIONS OF GASTRIC AND DUODENAL ULCERS

GASTRIC PERFORATION

The two most serious complications of gastric or duodenal peptic ulcers are perforation and hemorrhage. The frequency of acute perforations in patients hospitalized for peptic ulcer varies from 2% to 25%. Perforation occurs with far greater frequency in men than in women. It is also recognized that peptic ulcer tends to perforate more often in individuals between the ages of 25 and 50 years than in younger or older persons. Fortunately, these two complications appear to have decreased over the last several decades with the wide-spread use of flexible upper endoscopy for diagnosis of ulcer disease and the advent of improved medical treatments with proton pump inhibitors and for H. pylori infection.

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