Digestive System Anatomy PDF

DIGESTIVE SYSTEM - composed of organs whose primary functions are ingestion, digestion, absorption of food and excretion of undigested food - it include the mouth, pharynx, esophagus, stomach, small and large intestines and the accessory digestive organs ( Salivary glands, Liver, pancreas and gall...

DIGESTIVE SYSTEM - composed of organs whose primary functions are ingestion, digestion, absorption of food and excretion of undigested food - it include the mouth, pharynx, esophagus, stomach, small and large intestines and the accessory digestive organs ( Salivary glands, Liver, pancreas and gall bladder)  Histologic Characteristics - Walls of the Digestive tract composed of the following: 1. Tunica mucosa- consist of the ff: - functions: absorptive, secretory, and protective a. Epithelium- all are lined by simple columnar except mouth, pharynx, esophagus, and lower anus which are lined by stratified sq. non keratinized b. Lamina propria- loose areolar tissue c. Muscularis mucosa - made up of smooth muscles  2. Submucosa - Connective tissue consisting of the ff: blood vessels, lymphatics, and nerves - Major function is nutritive and protective 3. Tunica muscularis - Usually 2 layers of smooth muscles, inner circular and outer longitudinal muscle layer - Stomach has 3 layers of tunica muscularis, inner oblique, middle circular and outer longitudinal muscle layer 4. Tunica serosa - Visceral peritoneum - It is a single layer of simple squamous epithelium which secretes a small amount of serous lubricating fluid which reduces friction among the GI tract organs and the body wall  MAIN DIVISIONS I. Digestive tract E. Small intestines - duodenum A. Oral cavity - jejunum B. Pharynx - ileum - oropharynx F. Large intestine - cecum with vermiform - laryngopharynx appendix C. Esophagus - ascending colon D. Stomach - transverse colon - descending colon - sigmoid colon (pelvic colon) - rectum - anal canal  II. Accessory organs/glands: A. Lips B. Teeth C. Tongue D. Salivary glands: 1. Big - parotid - submandibular - sublingual 2. Small - lingual - labial - buccal E. Liver F. Gall bladder G. Pancreas  MOUTH 1. Oral vestibule - space bounded anteriorly by lips and cheeks and posteriorly by teeth and gums 2. Oral cavity proper - space bounded by gums and teeth - the floor is the tongue - the roof is the hard and soft palate 3. TEETH - Two sets of teeth: a. deciduous teeth, or temporary (milk) B. permanent teeth. - The deciduous set consists of 20 teeth, 5 in each quadrant: 2 incisors, 1 canine, and 2 molars. 3. TEETH - Two sets of teeth: a. deciduous teeth, or temporary (milk) B. permanent teeth. - The deciduous set consists of 20 teeth, 5 in each quadrant: 2 incisors, 1 canine, and 2 molars. - The deciduous teeth erupt on the average between 6 and 24 months after birth and are usually shed between the ages of 6 and 12 - There are 32 permanent teeth in a full set, 8 in each quadrant: 2 incisors, 1 canine, 2 premolars, and 3 molars. - Eruption of the third molars, or wisdom teeth, is delayed until after the age of 18  TONGUE - papillae a. vallate - largest b. foliate c. fungiform d. filiform - taste buds: sensory organs of taste especially numerous around vallate papillae Nerves of tongue: 1. General sensory - lingual (CN V) (anterior 2/3 of tongue) - Glossopharyngeal (CN IX post. 1/3 of tongue) - Vagus (CN X) epiglottic area 2. Special sensory - anterior 2/3 - chorda tympani from VII - posterior 1/3 - glossopharyngeal (CN IX) 3. Motor - to intrinsic and extrinsic muscles of tongue - hypoglossal  5. SALIVAR Y GLANDS - secretions (salivary amylase) poured in the oral cavity starts digestion of carbohydrates. 1. Parotid - largest, lies on the posterior border of ramus of mandible - secretion is purely serous - duct: Stensen's - opens into the vestibule of mouth opposite second molar tooth - viral inflammation: mumps or parotitis - important structure embedded : facial nerve  2. Submandibular - second largest - mixed serous and mucous gland, more of serous - duct: Wharton's - which opens at sublingual papillae  3. Sublingual - smallest of 3 salivary glands - mixed serous and mucous but more of mucous ducts: Rivinu's - small opens at summit of sublingual fold Bartholin's - large; opens into sublingual papillae  Pharynx 3 Parts: 1. nasopharynx or epipharynx - located behind the nasal cavity 2. oropharynx or mesopharynx - located behind oral cavity proper - palatine tonsil bounded by palatoglossal and palatopharyngeal fold 3. Laryngopharynx - located behind larynx - continuous with the esophagus  Esophagus - a muscular tube extending from the pharynx to the stomach - with 3 anatomical constrictions: 1. at the pharyngo-esophageal junction 2. when left main bronchus crosses esophagus 3. when it enters the diaphragm  Stomach - located within peritoneal cavity - with greater and lesser curvatures - parts: 1. Fundus - found on the left border 2. Body 3. Pyloric antrum 4. Pylorus - tubular portion 5. cardiac region- area surrounding the point of entry of food  CARDIAC NOTCH (ORIFICE) ANGULAR NOTCH (ORIFICE) ANTRUM  Cells in the stomach 1. Parietal cell- secretes HCl and intrinsic factor 2. Chief cell- secretes pepsin 3. Mucus neck cell- secretes mucus 4. G cell- secretes gastrin  SWALLOWING TONGUE MOVES UPWARD SOFT PALATE CLOSES THE AND BACKWARD NASOPHARYNX  Small Intestines - longest - 20 ft - Parts: 1. duodenum - C-shaped - with 4 parts( superior, descending, transverse and ascending) - the CBD and main and accessory pancreatic ducts enter Gross Structural Characteristics: - major duodenal papilla - with sphincter of Oddi around common duct and main pancreatic duct of Wirsung - minor duodenal of accessory pancreatic duct of Santorini 2. Jejunum - located at the left upper quadrant 3. Ileum - longest, found at the right lower quadrant Jejunum: upper 2/5 (8ft) - more vascular wider and thicker than ileum Ileum: lower 3/5 (12ft) - provided with Peyer's patches or aggregated lymph nodules  Large Intestines - 5 feet long 1. cecum- widest 2. Vermiform appendix- located posteromedial to cecum 3. Ascending colon 4. Transverse colon 5. descending colon 6. sigmoid colon- S-shaped 7. Rectum- continuation of sigmoid at S3 vertebra 8. anal canal  Characteristic Features of Large Intestines 1. Plicae semilunaris 2. Haustra/sacculations 3. Taenia coli 4. Epiploicae appendices  Differences between Small intestine and large intestine Small Intestines Large intestines Mobile except duodenum Fixed ascending and descending colon Narrower lumen Wider lumen With peyer’s patches in the ileum With taenia coli, appendices eppiploicae, haustra/sacculation Plicae circulares Plicae semilunares Blood supply of GIT  Accessory Digestive Organs 1. Salivary glands a. Parotid gland - purely serous, with stensen’s duct that open into oral vestibule opposite the upper 2nd molar tooth b. submandibular gland - mixed - its duct, wharton’s opens into sublingual papilla c. sublingual gland - it has 2 ducts 1. Bartholin’s duct- opens into sublingual papilla 2. duct of rivinus- opens into sublingual fold  Liver - largest gland of the body - with right and left lobe - 2 smaller lobes a. quadrate lobe b. caudate lobe  Ligaments 1. Falciform ligaments - anatomical division of the liver 2. Coronary ligaments 3. Triangular ligaments  Inferior/Visceral surface 1. Fissure for ligamentum teres hepatis, ligamentum venosum 2. Fossa of Gallbladder and IVC 3. Porta hepatis 1. common bile duct 2. hepatic artery 3. portal vein 4. Lymphatics and nerves  Gall Bladder - location:undersurface of the liver - stores and concentrates the bile - parts: fundus, body, neck, infundibulum - mucosa, muscular layer and serosa - Spiral valve of heister  Pancreas - retroperitoneal at the back of the stomach - both endocrine and exocrine organs - with head, neck, body and tail and uncinate process - 2 duct: a. major duct of wirsung b. accessory duct of santorini  Extrahepatic Biliary tract - Common hepatic duct - formed by the union of right and left hepatic duct - Cystic duct - duct of gall bladder - Common bile duct - formed by the union of cystic duct and common hepatic duct Thank You!