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    Related Topics

    From Digestive System

    Jejunum
    Second portion of the small intestine.
    Cheeks
    Lateral walls of the oral cavity composed of muscle and fat.
    Duodenal Bulb
    Initial section of duodenum closest to the stomach.
    External Anal Sphincter
    Voluntary muscle around anus.
    Descending Colon
    Vertical segment of the colon on the left side.
    Ileum
    Final and longest portion of the small intestine.
    Epiploic Appendages
    Fat-filled pouches attached to colon.
    Cardia
    Upper opening of the stomach.
    Quadrate Lobe
    Small lobe located between gallbladder and round ligament.
    Hepatic Flexure
    Bend between ascending and transverse colon.
    Body
    Main central region of the stomach.
    Common Bile Duct
    Conveys bile from liver and gallbladder to duodenum.
    Sublingual Glands
    Salivary glands beneath the tongue.
    Hard Palate
    Bony anterior portion of the roof of the mouth.
    Submandibular Glands
    Salivary glands beneath the mandible.
    Laryngopharynx
    Lower part of pharynx leading to esophagus.
    Rectum
    Straight section of the colon leading to anus.
    Liver
    Largest gland in the body with roles in metabolism and bile production.
    Pylorus
    Distal part of stomach leading to duodenum.
    Palatine Tonsils
    Lymphatic tissues on either side of the oropharynx.
    Lower Esophageal Sphincter
    Muscle at the junction of esophagus and stomach.
    Teniae Coli
    Longitudinal muscle bands of colon.
    Main Pancreatic Duct
    Primary duct draining pancreatic juices.
    Haustra
    Pouch-like segments of colon.
    Ligamentum Venosum
    Remnant of ductus venosus in liver.

    Stomach

    Reviewed by our medical team

    Muscular sac that begins digestion of protein.

    Overview

    The stomach is a muscular, hollow organ of the digestive system that plays a central role in the mechanical and chemical breakdown of ingested food. It serves as a reservoir where food is mixed with gastric secretions to form chyme, which is gradually released into the small intestine. It also acts as a barrier, immune organ, and endocrine gland, making it essential for both digestion and systemic regulation.

    Location

    The stomach is located in the upper left quadrant of the abdomen, extending into the epigastric and sometimes left hypochondriac regions. It:

    • Lies below the diaphragm, posterior to the left lobe of the liver

    • Is anterior to the pancreas and superior to the transverse colon

    • Varies in size and position depending on the volume of contents and body habitus

    Structure

    The stomach is divided into several anatomical regions:

    • Cardia: Area around the esophageal opening

    • Fundus: Dome-shaped superior portion, usually filled with gas

    • Body (corpus): The central, largest region responsible for most mixing and secretion

    • Pylorus: Divided into the antrum and pyloric canal, it regulates passage into the duodenum via the pyloric sphincter

    Its wall has four primary layers:

    • Mucosa: Contains gastric glands and rugae (folds)

    • Submucosa: Rich in blood vessels and lymphatics

    • Muscularis externa: Three muscle layers (oblique, circular, longitudinal) for powerful mixing

    • Serosa: Outer peritoneal covering

    Function

    The stomach performs several digestive and regulatory functions:

    • Storage: Temporarily holds ingested food and regulates its release into the small intestine

    • Mechanical digestion: Churns food into chyme using coordinated muscular contractions

    • Chemical digestion: Secretes gastric juices including hydrochloric acid (HCl), pepsinogen, and intrinsic factor

    • Intrinsic factor secretion: Necessary for vitamin B12 absorption in the ileum

    Physiological Role(s)

    The stomach supports multiple physiological processes:

    • Defense: Acidic environment kills ingested pathogens and denatures harmful proteins

    • Hormonal regulation: Produces hormones such as gastrin (stimulates acid production), ghrelin (stimulates appetite), and somatostatin (inhibits acid secretion)

    • Neural integration: Works with enteric and autonomic nervous systems for coordinated motility and secretion

    • Volume accommodation: Rugae allow the stomach to stretch and accommodate large meals without increasing internal pressure

    Clinical Significance

    The stomach is frequently involved in gastrointestinal diseases and is a critical focus in endoscopic and surgical procedures:

    • Gastritis: Inflammation of the stomach lining due to infections (e.g., H. pylori), alcohol, NSAIDs, or stress

    • Peptic ulcer disease (PUD): Erosions in the gastric or duodenal mucosa caused by acid and pepsin

    • Gastric cancer: Often asymptomatic in early stages; associated with chronic gastritis, H. pylori infection, and certain dietary factors

    • Gastroesophageal reflux disease (GERD): Incompetent lower esophageal sphincter allows acid to reflux into the esophagus

    • Gastroparesis: Delayed gastric emptying due to vagus nerve dysfunction, often seen in diabetes

    • Bariatric surgery: Procedures like sleeve gastrectomy or gastric bypass alter stomach anatomy for weight loss and metabolic improvement

    The stomach is evaluated through diagnostic tools such as endoscopy, barium studies, CT imaging, and gastric pH testing. Understanding its function and pathology is essential in gastroenterology and internal medicine.

    Did you know? The large intestine absorbs water, and the remaining material is turned into waste for elimination.