Disorders of Swallowing and of the Esophagus

Paralysis of the Swallowing Mechanism

• Damage to the 5th, 9th, 10th cerebral nerve

• Complete abrogation of the swallowing act

• Failure of the glottis to close so that food passes into the lungs instead of esophagus

• Failure of the soft palate and uvula to close to the posterior nares so that food refluxes into the nose during swallowing

Achalasia and Megasophagus

• Achalasia is a condition in which the lower esophageal sphincter fails to relax during swallowing. It is due to the loss of ganglion cells of the myenteric plexus.

• Megaesophagus - peristalsis fails to occur properly and the esophagus is enlarged.

Disorders of the Stomach

Gastritis – Inflammation of the Gastric Mucosa

• Caused by chronic bacterial infection of the gastric mucosa

• In many people with chronic gastritis, the mucosa gradually becomes atrophic until little or no gastric gland digestive secretion remains.

Achlorhydria (and Hypochlorhydria)

• Achlorhydria – the stomach fails to secrete hydrochloric acid

• Hypochlorhydria – diminished acid secretion. When acid is not secreted, pepsin is also usually not secreted.

Pernicious Anemia in Gastric Atrophy

• Intrinsic factor must be present for adequate absorption of vitamin B12 from the ileum. In the absence of it, only about 1/50 of the vitamin B12 is absorbed. Without it, newly forming RBC won’t mature in the bone marrow which results to pernicious anemia.

Peptic Ulcer

• Excoriated area of stomach or intestinal mucosa caused by the digestive action of gastric juice or upper small intestinal secretions.

Two feedback control mechanisms normally ensure that neutralization of

gastric juices is complete:

When excess acid enters the duodenum, it reflexly inhibits gastric secretion and peristalsis in the stomach, both by nervous reflexes and by hormonal feedback from the duodenum, thereby decreasing the rate of gastric emptying.

The presence of acid in the small intestine liberates secretin from the intestinal mucosa, which then passes by way of the blood to the pancreas to promote rapid secretion of pancreatic juice. This juice also contains a high concentration of sodium bicarbonate, thus making still more sodium bicarbonate available for neutralization of acid.

Disorders of the Small Intestine

Abnormal Digestion of Food – Pancreatic Failure

• Loss of pancreatic juice means loss of trypsin, chymotrypsin, carboxypolypeptidase, pancreatic amylase, pancreatic lipase, and few other digestive enzymes.

• Without these enzymes, 60% of the fat entering the small intestine may be unabsorbed, and one third to one half of the proteins and carbohydrates.

Pancreatitis

• Inflammation of the pancreas

Malabsorption by the Intestinal Mucosa – Sprue

• In very severe cases of sprue, there is impaired absorption of proteins, carbohydrates, calcium, vitamin K, folic acid, and vitamin B12.

• As a result, the person suffers severe nutritional deficiency, osteomalacia, inadequate blood coagulation, macrocytic anemia.

Disorders of the Large Intestine

Constipation

• Slow movement of feces through the large intestine, often associated with large quantities of dry. hard feces in the descending colon that accumulate because of over-absorption of fluid

Diarrhea

• Results from rapid movement of fecal matter through the large intestine

Disorders of the Small Intestine

Abnormal Digestion of Food – Pancreatic Failure

• Loss of pancreatic juice means loss of trypsin, chymotrypsin, carboxypolypeptidase, pancreatic amylase, pancreatic lipase, and few other digestive enzymes.

• Without these enzymes, 60% of the fat entering the small intestine may be unabsorbed, and one third to one half of the proteins and carbohydrates.

Pancreatitis

• Inflammation of the pancreas

Paralysis of Defecation in Spinal Cord Injuries

• When the spinal cord in injured somewhere between the conus medullaris and the brain, the voluntary portion of the defecation act is blocked while the basic cord reflex for defecation is still intact.

General Disorders of the Gastrointestinal Tract

Vomiting

• Excessive distention or irritation of the duodenum provides an especially strong stimulus for vomiting

Nausea

•Nausea is the conscious recognition of subconscious excitation in an area of the medulla closely associated with or part of the vomiting center

General Disorders of the Gastrointestinal Tract

Vomiting

• Excessive distention or irritation of the duodenum provides an especially strong stimulus for vomiting

Nausea

•Nausea is the conscious recognition of subconscious excitation in an area of the medulla closely associated with or part of the vomiting center

Gastrointestinal Obstruction

• If the obstruction is beyond the stomach, antiperistaltic reflux from the small intestine causes intestinal juices to flow backward into the stomach, and this juices are vomited along with stomach secretions.

• If the obstruction is near the distal end of the large intestine, feces can accumulate in the colon for a week or more

Gases in the Gastrointestinal Tract; “Flatus”

•Can enter the gastrointestinal tract from three sources: swallowed air, gases formed in the gut as a result of bacterial action, gases diffuse from the blood into the gastrointestinal tract.