fluid and electrolyte movement Flashcards
what is the absorption of water diven by
transport of solutes (na+) from lumen of intestines to bloodstrean
what does reabsorption of na+ in intestine drive
water reabsorption in gi tract
diarrhoea
loss of fluid and solutes from gi tract
how may water mvoe
via transcellular or paraceullar routes
what are the mechanisms of postprandial na+ absorption in jejenum
na+/glucose and na+/ amino acid cotransport
where does na+/h+ exchnage occur
in jejenum at both apical and basolateral membranes
what are the apical membranes
nhe2 and nhe3
what are the basolateral membranes
nhe1
what contributes to the transepithelial movement of na+
nhe2 and nhe3
what is the cellular ph hosuekeepr
nhe1
what is the primary mechanisms of na+ absorpption iin the interdigestive period
na+/h+ and cl-/hc03 exchnage occuring in ileum and proximal colon
what is a cause of diarrhoea
reduction in nacl absorption
what mediates electrogenuc na+ absooprtin in distal colo
epithelial na+ channels
how does cl absorption occur
passively via transcellular or paracellular routes
how does cl secretion occur
from crypt cells
what does low intracellular na+ drive
inward movement of na+, k|+ and cl- via NKCC1how
does potassium recycle
via k+ channels
normally, why does little secretion of cl- occur
due to apical CFTR either being closed or not present
when does secretion of cl occur
when cftr is indirectly acivated by bacterial enterotoxins, several hormones and neurotransmitters, immune cells products and some laxatives
what if the overall effect of of cftr
secretory diarrhoea
causes of diarrhoea
impaired absirption of nacl
excess bile acid in colon congenital defects
drugs with antidiarrhoeal activity
opiods; codeine , loperamide
