Digestive System PDF

Digestive System  Student should be able to : 1- Define structures forming digestive system. ILOs 2- Enumerate their functions. 3- Enumerate salivary glands and their function. 4-Describe accessory glands of digestive system and their...

Digestive System  Student should be able to : 1- Define structures forming digestive system. ILOs 2- Enumerate their functions. 3- Enumerate salivary glands and their function. 4-Describe accessory glands of digestive system and their role in digestion.  Ingestion Functions Mastication of Deglutition digestive Absorption system Peristalsis Defecation  Digestive system Associated Digestive tract organs of digestion Teeth – tongue- salivary gland- pancreas- liver – gall bladder Digestive tract Extends from mouth to anus. tubular passage About 10m in length Consists of {mouth –pharynx- esophagus- stomach Small intestine- large intestine- rectum- anal canal}  Mouth (oral cavity): First part of the tract Ant (LIPS) Lat (CHEEKS) Superior( PALATE) Inferior( MUSCULAR FLOOR) Divided into Oral Vestibule cavity proper Content salivary Palatine Teeth Tongue tonsils glands  Teeth 32 in adult permeant ,16 in each jaw. Four types Incisors (4 pairs) Canines (2 pairs) Premolar (4pairs) Molars (6 pairs) 20 milky teeth deciduous Tongue Muscular organ Taste sensation Tied to floor with frenulum  Pharynx Funnel shaped passageway 12.5cm long. Connects oral &nasal cavities to esophagus &trachea. Divided Respiratory system into nasopharynx Oropharynx laryngopharyn Respiratory &digestive x NB. Muscles of pharynx is voluntary but not under voluntary control. Esophagus Collapsible muscular tube. 25cm long , 2cm diameter. Connects pharynx to stomach. Upper esophageal sphincter (cricopharyngeal muscle). Prevent entry of air Lower esophageal sphincter. Prevents reflux regurgitation of food  Stomach Most distensible part. J shaped connects esophagus to duodenum. Initiate digestion of proteins. Located in epigastrium. Lower end guarded by strong sphincter. Accommodates volume from 0.5 to 5 L. Small intestine Long muscular tube. 6m in length. Connects stomach to large intestine. Located center of abdominal cavity surrounded by large intestine. Continues digestion ,absorption of water and digestive products. Divided into: Ileum Duodenum Jejunum about 3m About 25cm About Duodenum: Fixed c shaped tube. The concavity faced to left. Occupied by head of pancreas. Receive bile from liver via common bile duct. Receive pancreatic duct. Both unite forming hepatopancreatic ampulla. Divided into 4 parts.  Supported by mesentery its length is 15cm long, thus small intestine is thrown into folds called loops. Its main function is absorption, so mucosa is extensively increased by circular folds and villi. Exposed to microorganism protected by lymphoid tissues peyer's patches.  Large intestine  1.5m long. Extends from ileocecal junction to anal orifice. Absorbs water &electrolytes. Divided into Caecum & Ascending Transverse Descendin Sigmoid Rectum Anal canal appendix colon colon g colon colon Tongue Muscular organ Taste buds for taste sensation  Major digestive glands Salivary Liver pancreas glands  Produce saliva which acts as solvent in cleaning teeth Salivary dissolving the food chemicals so it can be tasted glands Contain enzymes Major Minor Located mucosa of Parotid palate ,lips and cheeks. Sublingual submandibular parotid Largest near ear Opens in vestibule opposite nd upper 2 molar Submandibular Inside & below mandilble Opens near frenulum of tongue Sublingual Under mucosa of floor of mouth Several ducts floor of mouth Clinical correlation: The commonest medical disease of parotid is mumps. The commonest surgical disease of salivary glands are calculus formation submandibular gland Mumps is related to which of the following glands? 1. Parotid 2. Submandibular 3. Sublingual 4. liver  Liver √ Largest internal organ. √ Two major lobes (right &left) √ Two minor lobes (caudate &quadrate) √ Vessels, ducts, nerves enter &exit liver through porta hepatis √ Divided into segments. √ Double blood supply (portal vein &hepatic artery). Gall bladder Pear shaped organ inferior surface of liver. Stores &concentrates bile secreted by liver. Hepatic cells secrete bile into caniculi inter lobular ducts right & left hepatic ducts common hepatic duct + cystic duct common bile duct + main pancreatic duct common hepatopancreatic duct. Clinical correlation Any obstruction biliary tree produce jaundice which is a yellow discoloration of skin due to excess bile pigment. Most common cause gallstones in CBD.  Pancreas Long, soft , lobulated gland. Head ,body and tail. Head located Whitin concavity of duodenum. Tail tapering near spleen. Secrets pancreatic juice Islets of Langerhans secrets insulin (endocrine part) Drained through 2 ducts Major pancreatic duct Minor pancreatic duct Co m m on bil e Hepatopancreatic du duct Minor ct duodenal Guarded by papilla ampulla of vater Major duodenal papilla nd 2 part of duodenum  1 2 3 4 5 7 6 8 9 10 11 12 Thank you