GI Flashcards
What does VIP do
inhibits acid secretion by stimulating somastatin production, released by the pancreas and SI
What are the foregut structures? and blood supply?
Mouth to proximal part of duodenum. Coeliac trunk
What is a midgut structure? and bloody supply?
Distal half of duodenum to splenic flexure of the colon. superior mesenteric artery
What is a hindgut structure and what is its blood supply?
Descending colon to the rectum. inferior mesenteric artery
Describe the coeliac trunk
major artery that supplies the foregut of the GI system, arises from the abdo aorta at 12th verterbrae, gives three branches: left gastric, common hepatoc and splenic arteries
What is the trachea lined with?
Stratified squamous cells
What is the stomach lined with?
Simple columnar epithelium with gastric glands: oxytinc (parietal = HCL and chief= pepsinogen) and pyloric glands. G cells=gastrin creates more HCL
What does enterokinase do?
Breakdown trypsinogen to trypsin
What do all peptide hormones act on?
G-protein coupled receptors
What does the pancreas secrete?
Islets of langerhans (endocrine)- hormone producing cells
Exocrine- digestive enzymes
Alkaline fluid from duct cells to neutralise acidic chyme
What do all dietary carbohydrates change into for absorption?
Monosaccharides
Phases of gastric acid secretion?
- cephalic- in head
- gastric- stomach
- intestinal- after food leaves stomach
What are the gastric secretions?
In fundus and body: HCL -> pepsinogen -> pepsin Intrinsic factor + gastroferrin -> binds b12 and Fe facilitating subsequent absorption Histamine -> HCL secretion Mucus -> protective
In pyloric gland:
Gastrin -> HCL secretion and motility
Somatostatin -> inhibits HCL secretion
What is the primary NA absorption mechanism in the interdigestive period?
Na/H and Cl/HCO3 exchange in parallel in ileum and proximal colon, regulated by cAMP. cGMP and Ca2 reduce NaCl absorption by affecting CFTR channel
What regulates Na absorption in distal colon?
Enac channels increased by aldesterone