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    Related Topics

    From Digestive System

    Liver
    Largest gland in the body with roles in metabolism and bile production.
    Pylorus
    Distal part of stomach leading to duodenum.
    Internal Anal Sphincter
    Involuntary muscle around anal canal.
    Jejunum
    Second portion of the small intestine.
    Oropharynx
    Middle region of the pharynx behind the oral cavity.
    Abdomen
    The abdomen is the body region between the chest and pelvis housing vital digestive, metabolic, and excretory organs, protected by muscular and peritoneal layers.
    Hepatic Flexure
    Bend between ascending and transverse colon.
    Rectum
    Straight section of the colon leading to anus.
    Esophagus
    Muscular tube conveying food from the pharynx to the stomach.
    Anus
    Opening through which feces are expelled.
    Cecum
    First part of large intestine.
    Soft Palate
    Muscular posterior part of the roof of the mouth.
    Fundus
    Upper curved portion of the stomach.
    Cystic Duct
    Connects gallbladder to common bile duct.
    Minor Duodenal Papilla
    Opening for accessory pancreatic duct.
    Abdominal Cavity
    The abdominal cavity is the largest body cavity, housing vital digestive and excretory organs, lined by the peritoneum and essential for protection, metabolism, and organ movement.
    Hard Palate
    Bony anterior portion of the roof of the mouth.
    Lingual Frenulum
    Fold of mucous membrane anchoring the tongue to the floor of the mouth.
    Caudate Lobe
    Lobe of liver near inferior vena cava.
    Haustra
    Pouch-like segments of colon.
    Oral Cavity
    Entry point of the digestive system; includes teeth, tongue, and salivary openings.
    Cheeks
    Lateral walls of the oral cavity composed of muscle and fat.
    Teeth
    Structures in the jaws for mechanical breakdown of food.
    Duodenum
    First portion of the small intestine.
    Body of Pancreas
    Central elongated portion of pancreas.

    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 human stomach contains three layers of muscle that help break down food.