the epithelial interface


structural scales in the gut


at the small scale:


mucosal structure, ultrastructure and area


renewal of the active surface



at the large scale:


the physical bowel visualised


the functional bowel



final stages of digestion


protein into peptides


carbohydrates into oligosaccharides


compare lipid digestion



tour of the small intestine

break

transport across the boundary


transport mechanisms in the cell wall


active and passive transport


examples of transport systems (resumé)


sodium/nutrient co-transport and oral rehydration fluid


chloride secretion and cystic fibrosis



water balance


regional water flux

checking the balance

ingested versus secreted

input versus output

References and Advanced Reading. Endoscopic appearances of the mucosa of the small intestine (and other sections of the gut) are shown well at http://www.endoatlas.com/atlas_1.html. Gastrointestinal phyiology can be reviewed by considering the list of points presented as "Highlights" at the end of http://www.mfi.ku.dk/ppaulev/chapter22/kap%2022.htm (penultimate section on page, before "Further Reading"). [both links valid on 19th May '03]

Sample multiple-choice question for discussion. Concerning water and electrolytes (choose the best answer)... a)   more fluid is ingested into the gut than is secreted into it b)   the gut is the main organ in the body which controls water and electrolyte load c)   osmosis refers only to movement of water molecules d)   absorption of sodium into the body occurs passively down its concentration gradient e)   all of the above

The Big Picture: function of the gastrointestinal tract Intestinal Function 1. Gut Reactions: immune function, motility and (exocrine) secretion Intestinal Function 3. When things don't work out right: pathophysiology of diarrhea