Regulation & Release Of Stomach Acid

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To understand the regulation and release of stomach acid, we need to know some important type of cells present in stomach and duodenum [First part of small intestine], just after stomach.

Stomach
  • Parietal Cells : Releases Stomach Acid [HCL]
  • Chief Cells: Releases Pepsinogen
  • EnteroChromaffin Like Cells : Releases Histamine
  • G Cells : Releases Gastrin
Duodenum:
  • S cells : Releases Secretin
Regulation & Release of Stomach Acid

Increases Production Of Stomach Acid


Parietal cells are located in stomach and releases Gastric acid under direct influence of following factors:

  • Gastrin
  • Acetylcholine
  • Histamin

Gastrin is produced by G cells mostly located in stomach which gets signal to release Gastrin under following conditions:

  • Distension of Stomach : Most Important factor for the release of Gastrin
  • Amino Acids
  • Vagal Stimulation : Causes release of Acetylcholine and Gastrin Releasing Peptide [GRP]
Enterochromaffin like cells in stomach releases Histamine which has dual action:
It directly activated Parietal cells to release stomach acid
Potentiates the action of Acetylcholine and Gastrin on parietal cells.

stomach acid release
Stomach Acid Release & Regulation © washington.edu

 Decreases Production Of Stomach Acid


Somatostatin : Also known as growth hormone inhibiting hormone [GHIH] acts as a counterbalance for stomach acid release. It is produced in stomach, intestine and Delta cells of pancreas and inhibits acid secretion from parietal cells by three ways:
  • Inhibits the release of Histamine
  • Inhibits the release of Gastrin
  • Directly inhibits Parietal cells and decreases the production of stomach acids
S cells present in duodenum produces Secretin which are activated by presence of acid in small intestine and inhibits the production of Gastrin by G cells thus decreasing acid production by stomach. Secretin also causes release and production of pancreatic as well as biliary bircarbonate

Zollinger Ellison Syndrome is a condition where their is excessive secretion of Gastrin from G cells, which is discussed in detail in separate article
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Peptic Ulcer Disease: Causes & Etiology

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Causes of Peptic Ulcer Disease

  • Smoking
  • Alcohol 
  • Steroids

Are generally considered as causes of peptic ulcer disease, but contrary to this belief they do not cause peptic ulcer disease directly. These agents are known to cause gastritis and thus delaying the healing of peptic ulcer.

The direct conditions or factors that are associated with the formation of Peptic Ulcer Disease are as follows:

  • NSAIDS : Non Steroidal Anti-Inflammatory Drugs
  • Helicobactor Pylori Infection
  • Cancer of Stomach
  • Zollinger Ellison Syndrome [ZE Syndrome]
  • Crohn's Disease
  • Head Trauma
  • Prolonged Intubation with Mechanical Ventilation 

Most of the above mentions conditions are directly associated with the stress that body has to undergo and thus causing Peptic Ulcer Disease and we will discuss each of them in detail in separate article

Before we go any further, discussing about the causes of Peptic Ulcer Disease it is important to know that pathophysiology and etiology of the ulcer disease.

NSAIDS

NSAIDS are known to decrease the production of "Prostaglinds", a substance in the body which helps in secretion of mucous into the stomach which forms a protective barriers and protect against the acidic environment of stomach. Since NSAIDS decrease the production of Prostaglandins , the mucous production is also decreased and thus exposing epithelial cells of stomach to the acids of stomach causing ulcers.

STRESS

Stress related conditions like prolonged stay in ICU with intubation and mechanical ventilation or Head Trauma or burns causes constriction of blood vessels that supplies mucous cells of stomach. This reduced blood supply results in death of mucous cells and they get washed away, again exposing the stomach to acids of stomach and thus causing peptic ulcer disease.

The Physiology of acid production in stomach and their related pathological condition or diseases will be discussed in detail in subsequent articles will give you a better understanding of ulcers and disease associated with high production of acids and their involvement in causing peptic ulcer disease.

Few noticeable points should always be remembered. Single most important cause of Peptic Ulcer Disease and symptoms of peptic ulcer disease is Helicobacter Pylori Infection which almost accounts for 80-90 percent of duodenal ulcers and around 60-70 percent of stomach ulcers.While around 10% of ulcers disease does not have any known causes, thus idiopathic.  
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Peptic Ulcer Disease : Signs & Symptoms

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What is Peptic Ulcer Disease?

Peptic Ulcer Disease [PUD] is a misnomer. In early 20th century it was believed that the ulcer of stomach and duodenum [First part of small intestine, just after stomach] was caused by gastric enzyme Pepsin and thus it was started to be called as peptic ulcer disease.

Basically, peptic ulcer disease is a pathological condition with  formation of ulcers either in stomach or in duodenum. Duodenal ulcers are 4 times more common than gastric [stomach] ulcers. Another important distinction between gastric ulcers and duodenal ulcer is that around 4-5 percent of stomach ulcers can be due to malignant tumor, thus justifying multiple biopsies to rule out any carcinogenic origin. Duodenal ulcers are most of the time benign and does not require multiple biopsies.

Signs & Symptoms of Peptic Ulcer Disease

Symptoms of peptic ulcers gives an important clue towards diagnosis of the disease. Though, these signs and symptoms are not enough to distinguish between Gastric or duodenal ulcers or even the diagnosis of ulcer alone.

  • Nausea & Vomiting is present in both gastric and duodenal ulcers. 
  • Most common presentation of Peptic ulcer is mid-epigastric pain. The pain of stomach ulcers usually increases with food , while in duodenal ulcers usually the midepigastric pain decreased after taking food.
  • Weight loss is also associated with peptic ulcer disease. Since pain of gastric ulcer increases with the intake of food they are more likely to cause increase in weight loss when compared to duodenal ulcers where pain is relieved after having a meal.
  • Tenderness of abdomen is usually not present in almost 80-85 percent of cases of peptic ulcer disease, until the ulcer has caused perforation.
  • Other important symptoms might include hematemesis [Vomiting of blood] or malena [ black colored or tarry stools due to oxidation of iron in hemoglobin]

The above signs and symptoms are not enough to distinguish between gastric and duodenal ulcers and the patient might need and endoscopy or special imaging technique like barium swallow or upper gastrointestinal series.

There can be many causes of peptic ulcer and some special techniques can be required for proper diagnosis and treatment of peptic ulcer disease which we will discuss in detail in subsequent articles.
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Barrett's Esophagus Diagnosis & Treatment

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Barrett's Esophagus is a condition where epithelium of lower esophagus changes from the normal Squamous to Columnar epithelium due to long standing Gastroesophageal Reflux Disease or GERD. The Changes are histological or at cellular level. 

Causes of Barrett's Esophagus

Cause of Barrett's esophagus is GERD, therefore patients usually complaint of epigastric pain radiating below the sternum with bad metallic taste in mouth. The Barrett's esophagus develop into adenocarcinoma of esophagus with usual rate of progression being 0.5 to 1 percent per year.

Diagnosing Barrett's Esophagus

Diagnosis of Barrett's Esophagus is made by Endoscopy which is performed if the patient has GERD for more than 5 years. Endoscopy is performed regardless of duration of GERD if patient has "Alarm Symptoms" like dysphagia (Difficulty in Swallowing) , odynophagia (pain while swallowing), weight loss, heme positive stools or anemia , elderly patients.

Continuous monitoring with repeat endoscopy is required as Barrett's esophagus can develop into esophageal cancer

Patients with Barrett's Esophagus should undergo repeat endoscopy every 2-3 years to see if dysplasia or esophageal cancer has developed. If the patient has low grade dysplasia endoscopy should be done every 2-3 months to determine the progression of lesion and see whether the low grade dysplasia has progressed to cancer or resolved.

Patients with high grade dysplasia should always undergo distal or lower esophagectomy because of its high rate of progression to  esophageal cancer. 

Barium studies are usually normal in patients with Barrett's Esophagus.

Treatment Of Barrett's Esophagus

Treatment of Barrett's esophagus is done by treating GERD, if endoscopy shows high grade dysplasia distal esophagectomy is required.

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Gastroesophageal Reflux Disease [GERD] Diagnosis & Treatment

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Gastroesophageal reflux disease is a condition where LES or lower esophageal sphincter is not able to remain in the state of contraction which results in back flow of gastric acids from stomach to esophagus. The causes of Gastroesophageal reflux disease can be food, drugs and various drinks.

Diagnosis Of Gastroesophafeal Refux Disease [GERD]

Diagnosis of Gastroesophageal Reflux Disease [GERD] is mostly clinical. Which means doctor does not have to do any specific test to diagnose GERD. The clinical signs & symptoms of GERD are enough for diagnosing Gastroesophageal Reflux Disease [GERD].

If a person has Epigastric pain which is radiating below the sternum with bad metallic taste in mouth GERD can be suspected and treatment can be started. If clinical diagnosis is made treatment can be started immediately. 

Only if the diagnosis of GERD is not clear or the patient's clinical presentation is equivocal a specific test called as 24-Hour PH monitoring is required. 24 hour PH monitoring is done by placing an electrode few centimeters below gastroesophageal junction (place where gullet and stomach meets). The instrument records the PH and average PH of that area is determined. 

Endoscopy can be done to see the changes in the lower esophagus, but a normal endoscopic finding does not exclude the presence of Gastroesophageal reflux disease [GERD]

Treatment of Gastroesophageal Reflux Disease [GERD]

Medical Treatment: Drugs can be used to treat Gastroesophageal Reflux Disease effectively. Three types of drugs can be used

  • Proton Pump Inhibitors (PPIs): Example: Omeprazole, Pantoprazole, Rabeprazole. All have equal efficacy. Goal is to keep PH of the stomach acid above 4.0.
  • H2 Blockers: These class of drugs are used if the symptoms are mild or moderate and are intermittent.
  • Prokinetic Drugs: Drugs like metachlopromide can be used to relieve the symptoms of GERD. Another prokinetic drug "Cisapride" was discontinued from US due to its fatal adverse effect. Cisapride was known to cause Ventricular Arrhythmias.

H2 Blockers and Prokinetic drugs have equal efficacy in treating mild intermittent forms of Gastroesophageal Reflux disease. But these drugs should not be used if symptoms are severe. For severe symptoms of GERD PPIs are the best class of drugs.

Surgical Treatment: The goal of surgical treatment is to tighten the Lower Esophageal Sphincter (LES) so that stomach acids do not flow back or upwards to esophagus. The indications of surgical treatment for GRED are as follows:
  • If patient does not respond to medical treatment with Proton Pump Inhibitors
  • Side Effects of PPIs: diarrhea & headache
  • Alternative to life long or long term medical treatment with PPIs
Two surgical methods are most commonly used to treat GERD surgically:
  • Laproscopic Nissen's Fundoplication
  • Purse-String Suture in LES to make it tighter.
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