Lecture 6: GIT PDF

 Gastro-intestinal tract (Digestive system) Mouth cavity Parts :  Mouth cavity proper: the part surrounded by the gum and teeth. wy  Ve...

 Gastro-intestinal tract (Digestive system) Mouth cavity Parts :  Mouth cavity proper: the part surrounded by the gum and teeth. wy  Vestibule: the part between the cheeks & lips externally and gum and teeth internally. Content:  Tongue: important for: da  Speech  Swallowing  Contain receptors for general and taste sensation.  Teeth: there are 2 types of teeth; en  Deciduous (milk) teeth in children (20)  Permanent teeth in adults (32).  Openings of the ducts of salivary glands: secrete saliva in the mouth Site H Parotid Submandibular Side of face behind mandible Below mandible Sublingual Floor of mouth R. Size The largest In between The smallest Duct termination Mouth vestibule at upper 2nd molar Floor of the mouth Secretion Watery Viscid D Anatomist “GIT” Page 1  Pharynx 15 cm common pathway for air & food (see the respiratory system lecture). N.B: mouth cavity is connected to oropharynx through oropharyngeal isthmus Esophagus 25 cm muscular tube which transmit food from the pharynx to the stomach wy Stomach  It is the most dilated part of the alimentary canal.  It lies in the upper left part of the abdominal cavity.  It is J-shaped having: da  2 ends: cardiac & pyloric ends.  2 borders: lesser curvature and greater curvature  2 parts: cardiac part (fundus and body) & pyloric part. Small intestine en  Length: 6 meters.  Site: in the central & lower parts of the abdomen  Parts: It consists of:  Duodenum: H  It is the most fixed and shortest part "25 cm" of small intesti  It is C-shaped formed of 4 parts (1st, 2nd, 3rd & 4th). R.  It receives the the main pancreatic duct& common bile duct at its 2nd part  Jejunum:.  It is the middle part of the small intestine.  It resembles about 2/5 of the length of the small intestine "2.5.meter" D  It has wide lumen with high vascular thick wall  Ileum:  It is the distal part of the small intestine.  It resembles about 3/5 of the length of the small intestine "3.5 meter".  It has narrow lumen with less vascular thin wall Anatomist “GIT” Page 2  Large intestine  Length:1.5 meters.  Site: in the periphery of the abdomen.  Character: wy  tenia coli "3 longitudinal bands"  sacculation / haustration "segmental appearance"  appendices epiploic "fat filled sacs"  Parts: da  Cecum "widest part of large intestine"  Vermiform appendix "narrowest part of large intestine"  Ascending colon en  Right colic flexure  Transverse colon  Left colic flexure  Descending colon  Pelvic (sigmoid) colon  Rectum H Length Large intestine 1.5 m Small intestine 6m R.  Anal canal. Diameter Large Small Vili Absent Present Tenia coli Present Absent D Sacculation Present Absent Appendices epiploic Present Absent Anatomist “GIT” Page 3  Liver  It is the largest gland in the body “about 1.5 kg”.  Site: lies in the right upper part of the abdomen.  Functions: 1. Synthesis of s albumin wy 2. Secretes bile (which is important for fat digestion). 3. Synthesis of clotting factors 4. Detoxifies several metabolites (e.g.: bilirubin and estrogen). da N.B: liver is formed of small left lobe & large right lobe containing caudate and quadrate lobe Gall bladder  Shape: pear-shaped sac en  Site: at the inferior surface of the liver.  Function: It stores and concentrates bile. H Then bile passes through its duct "cystic duct" to reach the 2nd part of duodenum. Pancreas R.  Site: lies transversely across the posterior abdominal wall.  Parts: head, neck, body and tail.  Functions: D  Endocrine gland: secretes insulin & glucagon hormones “regulate blood glucose”  Exocrine gland: secretes pancreatic enzymes through main & accessory pancreatic ducts that open at 2nd part of duodenum Anatomist “GIT” Page 4