GI TERMS - absorption: The active or passive transfer of...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
absorption: The active or passive transfer of substances from the lumen of the GI tract to the extracellular fluid. When digested nutrients have been absorbed and have reached the body’s cells, cellular metabolism directs their use or storage. acetylcholine: acid secretion: Parietal cells deep in the gastric glands secrete gastric acid, which helps kill bacteria and other ingested microorganisms. Acid denatures proteins by breaking disulfide and hydrogen bonds. Parietal cells also secrete intrinsic factor. This forms complexes with vitamin b12 and is aseential for b12 absorption in the intestine. [food or cephalic reflexes initiate gastric secretion. Gastrin stimulates acid secretion by direct action on parietal cells or indirectly through histamine. Acid stimulates short reflex secretion of pepsinogen. Somatostatin release by hydrogen is the negative feedback signal that modulates acid and pepsin release.] amino acids: molecule with a central carbon atom, linked to a hydrogen atom, an animo group, a carboxyl group, and various groups of atoms designated “r” amylase: Breaks starch into maltose after the enzyme is activated by cl- in saliva. Maltose physically tastes sweeter than starch. Anus: End of the GI tract. Any waste remaining in the lumen at the end of the GI tract leaves the body through the anus. apical membrane: mucosal surface. Secreting cells here release enzymes, mucus, and paracrine molcules into the lumen basolateral membrane: surface of the epithelium contacting the ECF. bicarbonate secretion: Bicarbonate secretes into the small intestine to neutralize the acid from the stomach. Some is secreted by duodenal cells, but most comes from the pancreas. The exocrine portion of the pancrease called acini opens into ducts. These secrete digestive enzymes, and the duct cells secrete bicarbonate. The pancreas also secretes hormones from the islet cells. Bicarbonate production trquires high levels of carbonic anhydrase. Chloride enters the cells on the basolateral NKCC cotransporter and leaves via an apical CFTR channel. Luminal cl then reenters the cell in exchange for bicarbonate entering the lumen. The hydrogen atoms reabsorbed into the intestinal circulation helps balance the bicarbonate
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/20/2012 for the course BIO 89515 taught by Professor Janmachart during the Fall '09 term at University of Texas at Austin.

Page1 / 2

GI TERMS - absorption: The active or passive transfer of...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online