Digestive

• The digestive system consists of organs whose primary functions are ingestion, digestion, absorption of food and excretion of undigested food, including the mouth, pharynx, esophagus, stomach, small and large intestines and the accessory digestive organs such as the liver, pancreas and gall bladder.
• Accessory duct of S antorini is a part of the extrahepatic biliary tract.
• Common bile duct is formed by the union of cystic duct and common hepatic duct.
• Cystic duct is the duct of gall bladder.
• Common hepatic duct is formed by the union of right and left hepatic duct.
• The walls of the Digestive tract are composed of the Tunica mucosa, Epithelium, Lamina propria, Muscularis mucosa, Submucosa, Tunica muscularis, Tunica serosa, Visceral peritoneum.
• The major organs of the Digestive tract include the Oral cavity, Pharynx, Esophagus, Stomach, Small intestines, and Large intestine.
• The accessory organs/glands of the Digestive tract include Lips, Teeth, Tongue, Salivary glands, Liver, Gall bladder, and Pancreas.
• The Pharynx consists of three parts: Nasopharynx, Oropharynx, Laryngopharynx.
• The Esophagus is a muscular tube extending from the pharynx to the stomach about 10 inches long, with three anatomical constrictions: at the pharyngo-esophageal junction, when the left main bronchus crosses the esophagus, and when it enters the diaphragm.
• The Stomach is located within the peritoneal cavity, has greater and lesser curvatures, and parts: Fundus, Body, Pyloric antrum, Pylorus.
• Submandibular gland is the second largest, is mixed serous and mucous, and its duct, Wharton's, opens at the sublingual papillae.
• Nerve supply of tongue includes general sensory (lingual nerve, CN V), special sensory (chorda tympani from VII, glossopharyngeal nerve, CN IX), and motor (protrusion of tongue to intrinsic and extrinsic muscles of tongue, hypoglossal nerve).
• Sublingual gland is the smallest of the three salivary glands, is mixed serous and mucous, and its ducts, Rivinus's and Bartholin's, open at the summit of the sublingual fold.
• Eruption of the third molars, or wisdom teeth, is delayed until after the age of 18.
• Permanent teeth (32) include 8 in each quadrant: 2 incisors, 1 canine, 2 premolars, and 3 molars.
• Tongue has papillae of various types: largest foliate, filiform, fungiform, and taste buds are especially numerous around vallate papillae.
• Parotid gland is the largest, lies on the posterior border of ramus of mandible, and its secretion is purely serous with duct, Stensen's, that opens into the vestibule of mouth opposite the second molar tooth.
• Gall Bladder is located under the surface of the liver, stores and concentrates the bile, and consists of fundus, body, neck, infundibulum, mucosa, muscular layer, and serosa.
• Parotid gland is purely serous with Stensen’s duct that opens into the oral vestibule opposite the upper second molar tooth.
• Deciduous teeth (20) erupt on the average between 6 - 24 months after birth and are usually shed between the ages of 6 and 12.
• Sublingual gland is mixed with two ducts: Bartholin’s opens into the sublingual papillae, and duct of Rivinus opens into the sublingual fold, starting the digestion of carbohydrates.
• Submandibular gland is mixed with its duct, Wharton’s, opening into the sublingual papillae.
• Pancreas is retroperitoneal at the back of the stomach, both endocrine and exocrine organs, with head, neck, body, and tail, and uncinate process.
• The deciduous set consists of 20 teeth, 5 in each quadrant: 2 incisors, 1 canine, and 2 molars.
• Ascending colon, transverse colon, and descending colon are parts of the large intestine.
• Ileum is the longest part of the alimentary canal, found at the right lower quadrant, and is provided with Peyer's patches or aggregated lymph nodules.
• Chyme is a liquid milky substance after digestion, the longest part of the alimentary canal, and consists of 20 ft.
• Accessory organs/glands include lips, teeth, tongue, salivary glands, liver, gall bladder, and pancreas.
• Vermiform appendix is located posteromedial to the cecum.
• Differences between small intestine and large intestine include being mobile except for the duodenum, having a narrower lumen, and having taenia coli, appendices eppiploicae, haustra/sacculation.
• Oral vestibule is the space bounded anteriorly by lips and cheeks and posteriorly by teeth and gums.
• Plicae semilunaris, haustra/sacculations, taenia coli, and epiploicae appendices are characteristic features of the large intestine.
• Oral cavity proper is the space bounded by gums and teeth, with the floor being the tongue and the roof being the hard and soft palate.
• Cardiac region is the area surrounding the point of entry of food in the stomach.
• Parietal cell secretes HCl which kills pathogens and activates pepsinogen → pepsin.
• Chief cell secretes pepsin which is involved in the digestion of proteins.
• Anal canal is a part of the large intestine.
• G cell secretes gastrin which stimulates more production of HCl acid by the parietal cells.
• Rectum is the continuation of the sigmoid colon at the S3 vertebra.