Anatomy of Digestive System, Liver, pancreas, and gallbladder .pptx

The digestive system is responsible for breaking down food, absorbing nutrients, and eliminating waste. It includes several organs with distinct roles.
Major Organs Involved:
Mouth: Initial site of digestion, where mechanical and enzymatic breakdown begins.
Esophagus: Conduit for food to travel from the mouth to the stomach.
Stomach: Site of significant mechanical and chemical digestion.
Small Intestine: Primary location for nutrient absorption.
Large Intestine: Absorbs water and forms solid waste.
Accessory Organs: Liver, pancreas, and gallbladder support digestion via enzyme and bile production.

1. Anatomy of the Digestive System Presenter: Dheeraj Kumar MRIT, Ph.D. (Radiology and Imaging) Assistant Professor Medical Radiology and Imaging Technology School of Health Sciences, CSJM University, Kanpur

2. Overview of Digestive System The digestive system is responsible for breaking down food, absorbing nutrients, and eliminating waste. It includes several organs with distinct roles. Major Organs Involved: Mouth: Initial site of digestion, where mechanical and enzymatic breakdown begins. Esophagus: Conduit for food to travel from the mouth to the stomach. Stomach: Site of significant mechanical and chemical digestion. Small Intestine: Primary location for nutrient absorption. Large Intestine: Absorbs water and forms solid waste. Accessory Organs: Liver, pancreas, and gallbladder support digestion via enzyme and bile production. Overall Length of the Digestive Tract: Approximately 9 meters (30 feet) from mouth to anus.

3. Oral Cavity (Mouth) Oral Cavity Anatomy of the Oral Cavity: Includes teeth, gums, tongue, hard and soft palate, and salivary glands. Teeth: Adult humans have 32 teeth that assist in the mechanical breakdown of food. Tongue: Vital for manipulating food and aiding in swallowing. Salivary Glands: Produce saliva, which contains enzymes like amylase for the chemical breakdown of carbohydrates. Attachments: Teeth: Attached to the alveolar processes of the maxilla (upper jaw) and mandible (lower jaw). Tongue: Attached to the floor of the mouth by the frenulum.

4. Blood Supply: Branches of the external carotid artery: Lingual artery (supplies the tongue). Facial artery (supplies the lips and cheeks). Nerve Supply: Trigeminal nerve (V) for sensation, Facial nerve (VII) for taste.

5. Measurements: Teeth: About 20 mm (length of molars); incisors are 8-10 mm. Tongue: Approximately 10 cm long, varying by individual. Function: Begins the process of digestion by chewing and mixing food with saliva. Clinical Significance: Dental issues (caries, gingivitis), oral cancers, salivary gland infections.

6. Esophagus Anatomy of the Esophagus: A muscular tube about 25-30 cm long, running from the pharynx to the stomach. Lined by stratified squamous epithelium and has both circular and longitudinal muscle layers. Passes through the diaphragm at the esophageal hiatus (T10 vertebral level).

7. Attachments: Proximally attached to the pharynx and distally attached to the stomach at the lower esophageal sphincter. Anchored to the diaphragm at the esophageal hiatus. Blood Supply: Upper third: Supplied by the inferior thyroid artery. Middle third: Branches of the thoracic aorta. Lower third: Left gastric artery and inferior phrenic artery.

8. Nerve Supply: Vagus nerve (X) for parasympathetic innervation (stimulates peristalsis). Sympathetic trunk for sympathetic innervation (inhibits peristalsis). Measurements: Diameter: Around 2-3 cm, allowing the passage of food and liquids. Length: Extends about 25 cm from the pharynx to the stomach. Function: Transports food and liquids to the stomach via peristalsis. Clinical Significance: Conditions like GERD (gastroesophageal reflux disease), esophageal cancer, and achalasia.

9. Stomach Anatomy of the Stomach: J-shaped organ located in the upper left quadrant of the abdomen. Four major regions: Cardia , Fundus , Body , and Pylorus . The stomach has an inner lining of gastric mucosa that secretes acid and enzymes (like pepsin) to aid digestion. Attachments: Attached superiorly to the esophagus via the lower esophageal sphincter. Attached inferiorly to the duodenum via the pyloric sphincter. Supported by the lesser omentum (between the stomach and liver) and the greater omentum (covering the intestines).

10. Blood Supply: Left and right gastric arteries (along the lesser curvature). Left and right gastro-omental arteries (along the greater curvature). Nerve Supply: Vagus nerve (parasympathetic innervation for motility and secretion). Celiac plexus (sympathetic innervation for regulating blood flow and inhibiting digestive activity).

11. Measurements: Volume: Can hold around 1 to 1.5 liters of food. Length: Approximately 25 cm long. Width: 10-12 cm wide when distended. Thickness of the wall: 3-5 mm . Function: Breaks down food into a semi-liquid form called chyme, secretes digestive enzymes and gastric acid. Clinical Significance: Peptic ulcers, gastritis, stomach cancer, and pyloric stenosis.

12. Small Intestine Anatomy of the Small Intestine: The longest part of the digestive tract, measuring 5-6 meters in length. Three sections: Duodenum , Jejunum , and Ileum . Inner surface lined with villi and microvilli for increased absorption. Attachments: The duodenum is retroperitoneal and attached to the posterior abdominal wall. The jejunum and ileum are suspended from the posterior abdominal wall by the mesentery , a double layer of peritoneum.

13. Blood Supply: Duodenum: Supplied by branches of the gastroduodenal artery and superior mesenteric artery . Jejunum and Ileum: Supplied by the superior mesenteric artery . Nerve Supply: Parasympathetic: Vagus nerve (X). Sympathetic: Superior mesenteric plexus.

14. Measurements: Duodenum: Approximately 25 cm long (C-shaped). Jejunum: 2.5 meters long. Ileum: 3.5 meters long. Function: Nutrient absorption (carbohydrates, proteins, fats) through specialized cells in the villi. Clinical Significance: Conditions like Celiac disease (malabsorption), Crohn's disease , and intestinal obstruction .

15. Large Intestine Anatomy of the Large Intestine: Approximately 1.5 meters long, starting from the cecum and ending at the rectum . Composed of the cecum , ascending colon , transverse colon , descending colon , sigmoid colon , and rectum . Lined with simple columnar epithelium and goblet cells, which secrete mucus. Attachments: The large intestine is attached to the posterior abdominal wall via the mesocolon . The ascending colon and descending colon are retroperitoneal, while the transverse colon and sigmoid colon are intraperitoneal.

16. Blood Supply: Cecum, ascending colon, and transverse colon: Supplied by the superior mesenteric artery . Descending colon, sigmoid colon, and rectum: Supplied by the inferior mesenteric artery . Nerve Supply: Parasympathetic: Vagus nerve for the proximal colon, and pelvic splanchnic nerves for the distal colon. Sympathetic: Superior and inferior mesenteric plexuses.

17. Measurements: Diameter: 6-7 cm in the cecum, narrowing to 3 cm in the sigmoid colon. Length: 1.5 meters . Function: Absorbs water and electrolytes, forms and stores feces. Clinical Significance: Conditions like diverticulitis , colorectal cancer , irritable bowel syndrome (IBS), and constipation .

18. Liver Anatomy of the Liver: The largest solid organ in the body, weighing 1.2-1.5 kg . Divided into four lobes : Right, Left, Caudate, and Quadrate. Located in the right upper quadrant of the abdomen, protected by the rib cage. Attachments: Attached to the diaphragm and anterior abdominal wall via the falciform ligament . Connected to the stomach and duodenum via the lesser omentum .

19. Blood Supply: Receives blood from the hepatic artery (oxygenated) and the portal vein (nutrient-rich, deoxygenated blood from the intestines). Blood leaves the liver through the hepatic veins into the inferior vena cava. Nerve Supply: Parasympathetic: Vagus nerve. Sympathetic: Hepatic plexus.

20. Measurements: Length: Approximately 15-17 cm . Width: About 20 cm . Thickness: Around 10-12 cm . Function: Metabolism of nutrients (carbohydrates, proteins, and fats). Detoxification of blood, storage of glycogen. Production of bile for fat digestion. Clinical Significance: Conditions like hepatitis , cirrhosis , fatty liver disease , and liver cancer .

21. Gallbladder Anatomy of the Gallbladder: A small, pear-shaped sac located beneath the liver. Connected to the liver by the cystic duct and stores bile. Attachments: Connected to the liver by the cystic duct , which merges with the common hepatic duct to form the common bile duct .

22. Blood Supply: Supplied by the cystic artery , a branch of the right hepatic artery . Nerve Supply: Parasympathetic: Vagus nerve. Sympathetic: Celiac plexus.

23. Measurements: Length: About 7-10 cm . Width: 3-4 cm . Capacity: Can hold 50 mL of bile. Function: Stores and concentrates bile produced by the liver, releases bile into the small intestine to aid in fat digestion. Clinical Significance: Conditions like cholecystitis , gallstones , and biliary colic .

24. Pancreas Anatomy of the Pancreas: A soft, elongated gland located in the retroperitoneal space , extending from the duodenum to the spleen . Divided into three parts: Head , Body , and Tail . Attachments: Head of the pancreas is attached to the duodenum. Tail extends toward the spleen.

25. Blood Supply: Head: Supplied by the superior and inferior pancreaticoduodenal arteries . Body and Tail: Supplied by branches from the splenic artery . Nerve Supply: Parasympathetic: Vagus nerve. Sympathetic: Celiac and superior mesenteric plexuses.

26. Measurements: Length: About 15-20 cm . Width: 4-5 cm (at the head), narrowing to 1-2 cm (at the tail). Function: Exocrine function: Produces digestive enzymes (amylase, lipase, protease) released into the small intestine. Endocrine function: Produces hormones (insulin, glucagon) to regulate blood sugar. Clinical Significance: Conditions like pancreatitis , pancreatic cancer , and diabetes mellitus .

27. Spleen Anatomy of the Spleen: Located in the left upper quadrant of the abdomen, beneath the diaphragm and adjacent to the stomach. Oval-shaped, with a soft, purplish appearance, covered by a fibrous capsule. The spleen is not part of the digestive tract but is closely related due to its proximity and blood filtration role. Attachments: Attached to the stomach by the gastrosplenic ligament and to the left kidney by the splenorenal ligament . These ligaments help anchor the spleen in place within the abdominal cavity.

28. Blood Supply: Supplied by the splenic artery , which is a branch of the celiac trunk. Drained by the splenic vein , which joins the superior mesenteric vein to form the portal vein. Nerve Supply: Sympathetic fibers from the celiac plexus innervate the spleen.

29. Measurements: Length: Approximately 12 cm . Width: About 7 cm . Thickness: Around 4 cm . Weight: Around 150-200 grams . Function: Filters and removes old or damaged red blood cells. Produces and stores lymphocytes and other immune cells to fight infection. Acts as a reservoir for blood.

30. Clinical Significance: Conditions like splenomegaly (enlarged spleen), splenic rupture (from trauma), and hypersplenism (overactive spleen). The spleen may be removed (splenectomy) in certain medical conditions without major consequences due to compensatory mechanisms in the liver and bone marrow.

31. Peritoneum and Peritoneal Cavity Anatomy of the Peritoneum: The peritoneum is a serous membrane that lines the abdominal cavity and covers the abdominal organs. Consists of two layers: Parietal peritoneum : Lines the abdominal wall. Visceral peritoneum : Covers the surface of the abdominal organs. The space between these layers is called the peritoneal cavity , which contains a small amount of serous fluid that allows the organs to move smoothly.

32. Attachments: The peritoneum forms various folds and ligaments that anchor organs in place, such as the mesentery (supports intestines), greater omentum (covers intestines), and lesser omentum (between the stomach and liver). The mesocolon attaches the colon to the posterior abdominal wall.

33. Blood Supply: The peritoneum receives blood from the arteries supplying the abdominal organs, primarily the celiac trunk , superior mesenteric artery , and inferior mesenteric artery . Nerve Supply: Parietal peritoneum: Supplied by somatic nerves (sensitive to pain, temperature, and touch). Visceral peritoneum: Supplied by autonomic nerves (insensitive to pain but sensitive to stretch and chemical stimuli).

34. Measurements: The total surface area of the peritoneum is approximately 1.8 m² in adults. Function: Protects and supports abdominal organs. Facilitates movement of organs by providing a frictionless surface. Serves as a conduit for blood vessels, nerves, and lymphatics to and from the abdominal organs.

35. Clinical Significance: Peritonitis: Inflammation of the peritoneum, often due to infection or trauma. Ascites: Accumulation of fluid in the peritoneal cavity, commonly seen in liver cirrhosis. Adhesions: Bands of scar tissue that can form after surgery, causing organs to stick together.

36. Clinical Significance of the Digestive System Gastroesophageal Reflux Disease (GERD): A condition in which stomach acid frequently flows back into the esophagus, causing heartburn and discomfort. Often associated with a weak lower esophageal sphincter.

37. Peptic Ulcer Disease (PUD) Sores that develop on the lining of the stomach, small intestine, or esophagus due to excess acid or infection by Helicobacter pylori .

38. Inflammatory Bowel Disease (IBD): Includes Crohn's disease and ulcerative colitis, both of which cause chronic inflammation of the gastrointestinal tract.

39. Irritable Bowel Syndrome (IBS): A functional disorder characterized by abdominal pain, bloating, and changes in bowel habits without any underlying damage.

40. Liver and Gallbladder Disorders: Hepatitis: Inflammation of the liver, caused by viruses (Hepatitis A, B, C) or other factors like alcohol and drugs. Cholelithiasis (Gallstones): Solid particles that form in the gallbladder, causing pain, and potential bile duct obstruction.

41. Pancreatic Disorders: Pancreatitis: Inflammation of the pancreas, often due to gallstones, alcohol, or infection. Pancreatic Cancer: A highly aggressive cancer that often goes undetected until the advanced stage.

42. Colorectal Cancer: Cancer that starts in the colon or rectum, often associated with genetic mutations and dietary factors.

43. Diagnostic Imaging of the Digestive System Ultrasound: Primarily used to visualize abdominal organs like the liver, gallbladder, and pancreas. Non-invasive and safe, often used for detecting gallstones, liver abnormalities, and ascites.

44. Computed Tomography (CT) Scan: Provides detailed cross-sectional images of the digestive system. Helpful in detecting tumors, abscesses, and organ enlargement (e.g., hepatomegaly).

45. Magnetic Resonance Imaging (MRI): Useful for detailed imaging of soft tissues, especially in detecting liver lesions, pancreatic diseases, and bile duct abnormalities.

46. Endoscopy: A procedure where a flexible tube with a camera is inserted through the mouth to examine the esophagus, stomach, and duodenum. Used for biopsies and identifying ulcers, polyps, or tumors.

47. References Human Anatomy by BD Chaurasia Gray’s Anatomy for Students. Netter’s Atlas of Human Anatomy. Clinical Gastroenterology and Hepatology Journal. Radiopaedia.org for diagnostic imaging references. Journal of Digestive Diseases for clinical insights.