GI - diarrhea Flashcards
what is diarrhea
frequent passage of liquid feces
what might diarrhea be accompanied with
abdominal cramps and nausea
what is the physiological point of diarrhea
mechanism to rid gut of irritating substances
what are 4 causes of diarrhea
infection, anxiety, drugs, inflammatory disease
can diarrhea be deadly
yes, primary cause of death in infants in developing countries
what happens with water and electrolytes in diarrhea
disordered water and electrolyte transport in small intestine
what happens to gut motility in diarrhea
increased
what happens to fluid secretion in diarrhea
increased
what happens to fluid absorption in diarrhea
decreased
what happens to electrolytes in diarrhea
loss
which electrolytes are mostly lost with diarrhea
Na+
how much fluid does an adult take in every day
2+
how many litres of water does saliva and secretions from stomach, pancreas and liver add to small intestine every day
7 more litres
how many litres enter the small intestine every day
9
is there normally more absorption or secretion in the intestine
more absorption
what % of fluid entering the small intestine is absorbed
more than 90%
how much fluid usually reaches the large intestine
about 1 litre
how many mls of H2O end up being excreted in stool
100-200mL
what happens when there is a change in 2 directional flow of H2O and electrolytes in small intestine
causes an increased volume of fluid to enter large intestine
what happens when the volume of fluid in LI exceeds absorptive capacity
diarrhea
what kind of things are on intestinal epithelial cells (3)
ion channels, pumps and transporters
where are the ion channels, pumps and transporters on intestinal epithelial cells
both luminal and basolateral membranes
what causes absorption of H2O from small intestine
osmotic gradients created when solutes are absorbed from lumen
how does Na+ enter epithelial cells in the gut
via ENaC channels in the gut
or can be co-transported with glucose or amino acids
how does Na+ exit epithelial cells into the extracellular fluid
Na+/K+ ATPase
how does water enter epithelial cells
via aquaporins
why does water follow Na+ in epithelial cells
because Na+ goes into ECF, increases osmolarity, H2O follows passively through water channels
does water move alone? why?
it never moves alone, it always follows the movement of ions
how does H2O get secreted in the small intestine
NaCl is pumped back, Cl- creates osmotic gradient (h2o and other electrolytes follow)
how does Na+ enter the epithelial cells (from the ECF)
it is pumped in by a Na+ / Cl- co transporter
what happens after Na+ re-enters the epithelial cell (in secretion)
they return back via the Na+/K+ ATPase
how does Na+ enter the epithelial cells (from the ECF)
it is pumped in by a Na+ / Cl- co transporter
what happens after Cl-enters the epithelial cell (in secretion)
it passes into the lumen via the CFTR channel
what happens once Cl- gets secreted into the lumen
it creates an osmotic gradient and H2O and other electrolytes flow passively from the ECF via intercellular channels
what is secretory diarrhea
abnormal secretion of H2O and salts into SI
what causes secretory diarrhea (like molecule wise)
absorption of Na+ is impaired while secretion of Cl- continues or is increased
what happens with Na+ in secretory diarrhea
absorption is impaired
what happens with Cl- in secretory diarrhea
secretion is continued or increased