Physiology: H2O balance in the GI tract 2

Question 1

describe the role of CFTR on Cl secretion

Answer 1

normally little secretion of Cl occurs because CFTR either closed or not present
secretion Cl occurs when CFTR activated

Question 2

what can CFTR be indirectly activated by (4)

Answer 2

bacterial enterotoxins
hormones + neurotransmitters(e.g. acetylcholine)
immune cell products(e.g. histamine)
some laxatives(e.g. bile acid)

Question 3

what secondary messengers result in indirect activation of CFTR (3)

Answer 3

cAMP, cGMP and Ca

Question 4

give 4 causes of diarrhoea

Answer 4

impaired absorption NaCl, hypermotility, excessive secretion or non-absorbable/poorly absorbable solutes in intestinal lumen

Question 5

what part of GI tract can diarrhoea involve

Answer 5

small or large intestine

Question 6

what can diarrhoea result in

Answer 6

dehydration(Na + H2O loss), metabolic acidosis(HCO3 loss), hypokalaemia(K loss) and even death if severe

Question 7

what is the first priority in treatment of severe diarrhoea

Answer 7

maintenance of fluid + electrolyte balance

Question 8

describe the action of rehydration therapy

Answer 8

exploits SGLT1 to absorb Na and glucose, which causes accompanying H2O absorption