04.1 Stomach anatomy and function

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Questions and Answers

What is the primary function of G cells in the stomach?

To secrete pepsinogen

To absorb vitamin B12

To inhibit gastric acid secretion

To release gastrin (correct)

Which hormone is primarily involved in inhibiting gastrin release?

Cholecystokinin

Gastrin

Somatostatin (correct)

Secretin

What role do parietal cells play in the stomach?

Releasing hydrochloric acid and intrinsic factor (correct)

Producing gastrin

Modulating gastric motility

Secreting pepsinogen

Which of the following conditions is characterized by increased gastric acid secretion?

Zollinger-Ellison syndrome Signup and view all the answers

How does stomach distension impact gastric function?

Stimulates gastrin release Signup and view all the answers

What is a function of enteroendocrine cells in the stomach?

Modulating digestive processes Signup and view all the answers

Which hormone helps in regulating bicarbonate secretion in the stomach?

Secretin Signup and view all the answers

In which part of the stomach are chief cells primarily located?

Fundus and body Signup and view all the answers

What is the primary mechanism of action for Proton Pump Inhibitors (PPIs)?

Inhibit the H+/K+ ATPase in parietal cells Signup and view all the answers

Which of the following conditions is primarily treated with H2 receptor antagonists?

Chronic GERD Signup and view all the answers

What is the gold standard for diagnosing peptic ulcers?

Endoscopy Signup and view all the answers

Which symptom is commonly associated with Peptic Ulcer Disease?

Epigastric pain Signup and view all the answers

What complication can arise from chronic GERD?

Barrett’s esophagus Signup and view all the answers

What testing method is used to detect H.pylori infection?

Stool antigen test Signup and view all the answers

What protective element is crucial in preventing gastritis and ulcers?

Mucus-bicarbonate barrier Signup and view all the answers

What hormone is primarily responsible for inhibiting gastric acid secretion when the stomach pH is low?

Somatostatin Signup and view all the answers

Which of the following statements about antacids is true?

They neutralize stomach acid. Signup and view all the answers

In Zollinger-Ellison syndrome, what is primarily responsible for the excessive production of gastric acid?

Gastrin-secreting tumors Signup and view all the answers

What is the diagnostic approach used to assess for suspected peptic ulcers?

Endoscopy Signup and view all the answers

Which structure in the stomach provides a unique capability for grinding and mixing food?

Oblique muscle layer Signup and view all the answers

How is Helicobacter pylori infection typically detected?

Urea breath test Signup and view all the answers

What is the role of prostaglandins in the stomach?

Maintaining mucosal integrity and blood flow Signup and view all the answers

What induces the secretion of gastrin from G cells?

Stomach distension and food presence, especially proteins Signup and view all the answers

What primarily promotes healing of ulcers in the stomach?

Proton pump inhibitors (PPIs) Signup and view all the answers

Study Notes

Stomach Anatomy and Function

The stomach regulates motility and secretion through hormonal, neural, and paracrine control.
Its function includes food storage, digestion, and self-protection.
Gastrin, somatostatin, and secretin are key gastrointestinal hormones.
Distension influences gastric acid secretion.
The stomach protects itself with a thick mucus and bicarbonate layer.
Oblique muscle layer facilitates food grinding and mixing.
Enteroendocrine cells (G cells, D cells, S cells) regulate digestive processes.
Parietal cells secrete hydrochloric acid (HCl) and intrinsic factor.
Chief cells secrete pepsinogen, the precursor to pepsin for protein digestion.
Gastrin stimulates HCl secretion and enhances motility.
Somatostatin inhibits gastrin and acid production (important pH control).
Secretin stimulates bicarbonate secretion from the pancreas and inhibits gastric acid secretion.
Stomach blood and lymphatic supply, vitamin B12 absorption, and iron metabolism are crucial functions.
Gastritis, ulcers, and Zollinger-Ellison syndrome are conditions affecting stomach function.

Key Concepts

Enteroendocrine Cells: Specialized cells releasing hormones regulating stomach functions.
G cells: Located in the antrum, secreting gastrin (increases gastric acid and motility).
D cells: Located in the antrum, secreting somatostatin (inhibits gastrin and acid production).
Parietal Cells: Located in the fundus and body, secreting HCl and intrinsic factor.
Chief Cells: Located in the fundus and body, secreting pepsinogen.

Clinical Applications

Zollinger-Ellison Syndrome: Caused by gastrin-secreting tumors (gastrinomas) leading to hypergastrinemia and recurrent peptic ulcers.
Diagnosis uses fasting gastrin levels and imaging studies (endoscopy, CT scans).
Proton pump inhibitors (PPIs) reduce gastric acid production for ulcer treatment.
Treatment of Zollinger-Ellison Syndrome often includes surgical resection.

Pathophysiology

Acid Secretion Pathway: Gastrin, histamine, and acetylcholine stimulate HCl secretion by parietal cells.
Regulation: Somatostatin inhibits acid production when pH drops too low. This feedback loop is critical.
Motility: Three muscle layers (longitudinal, circular, oblique) enable mixing and grinding movements, converting food into chyme.

Pharmacology

Proton Pump Inhibitors (PPIs): Inhibit H+/K+ ATPase, reducing acid production important for GERD, peptic ulcers, and Zollinger-Ellison syndrome.
H2 Receptor Antagonists: Block histamine H2 receptors on parietal cells, reducing acid secretion.
Antacids: Neutralize stomach acid for quick symptom relief (heartburn, indigestion)

Differential Diagnosis

Peptic Ulcer Disease (PUD): Epigastric pain, possibly improving or worsening with food. Common causes are H. pylori infection and NSAID use. Diagnosis is typically confirmed through endoscopy, treatment involves acid suppression, and, in some cases, H.pylori eradication.
Gastritis: Inflammation of the stomach lining, common causes include H.pylori infection, chronic alcohol use, or NSAIDS, symptoms include nausea, bloating, and epigastric pain.
Hiatal Hernia: Part of the stomach pushes into the chest cavity. A contributing factor to GERD, leading to acid reflux, heartburn.
Barrett's Oesophagus: Chronic GERD causes changes in the esophageal lining, increasing risk for esophageal cancer.

Investigations

Endoscopy: Gold standard for diagnosing peptic ulcers, gastritis, malignancies. Allows visualization and biopsy.
Gastrin Level Test: Used to diagnose conditions with excessive gastrin production like Zollinger-Ellison syndrome.
H. pylori: Testing helps diagnose gastritis and peptic ulcer disease.
pH Monitoring: Measures acid exposure in the esophagus and confirms GERD diagnosis.

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