wk 5 7 physiology pharmacology of fluid balance Flashcards
t/f were sodium goes water will follow
true
2 routes which water will move in reabsorption
transcellular and paracellular
reabsorptio of na+ provides an osmotic force for reabsorption of water, what are the co-transporters in small intestine alone?
Na+/glucose co-transport
na+/amino acid co-transport (both in postprandial period)
Na/H+ exchange - duoenum and jejunum, stimulated by HCO3-
aldosterone regulates which mechanisms of transport for water and sodium ? found in distal region of colon
Epithelial na+ channels (ENaC)
Parallel Na+/H+ and Cl-/HCO3- exchange occurs in the 2
ileum and colon
- interdigestive period
to enter the membrane in mechanisms of postprandial Na+ absorption, the Na+/glucose and Na+/amino co-transport are used, how does it pass through the membrane
na+/K+atpase exchange
`t/f Na+/H+ exchange occurs at both the basal and apical membranes
true
NHE 1 - ph housekeeper
NHE3- enters lumen,
exchange at the apical membrane in the jejunum is stimulated by the alkaline environment, what causes this
presence of bicarbonate
which cellular mechanism of Na+ absorption is important in the fasting stage
Na+/H+ and Cl-/HCO3- exchange in parallel
t/f cAMP reduces NaCl absorption
true
cause of diarrhoea
also cGMP and Ca2+ reduce NaCl absorption
outline how secretery diarrhoea due to infection of E.Coli
heat stable entertoxin
activates adenylate cyclase
-incr intracellular cAMP
- reduced NaCl absorption
t/f ENaC is not a transporter
true
ion channel
how is Cl absorbed in small intestine
eletrogenic transport of Na+
(Na+/glucose and Na+/amino)
-this causes lumen to become negative, creating a driving force
t/f ENaC provides a negative lumen
true
drives Cl- in large intestine
t/f there are K channels in basolateral membrane
true
where does Cl- secretion occur
from crypt cells
which channel does Cl- travel accross for secretion
CFTR
what activates CFTR
bacterial endotoxins
heat stable enterotoxins
hormones/neurotransmitters (VIP,acetylcholine…)
immune cells products - prostaglandins,histamine
laxatives
opening of CFTR causes
secretory diarrhoea
diarrhoea causes
dehydration (Na+ and H20 loss), metabolic acidosis (HCO3- loss) and hypokalaemia
can be fatal - cholera
outline treatment for acute diarrhoea
usually no treatment - due to viral infection and not much can be done
maintenance of fluid and electrolyte balance (rehydration)
anti-ifective agents (if appropriatee) (ciprofloxin)
non-antimicrobial antidiarrhoeal agents
diarrhoea can occur due to impaired absorption of NaCl, what 4 things can cause this
congenital defects - absence of Cl-HCO3- exchanger
inflammation
infection (enterotoxins)
excess bile acid in colon
other than impaired absorption of NaCl, give 3 other causes of diarrhoea
non-absorbable solute (lactase defiency)
hypermotility
excessive secretion
what channel is required for adenylate cyclase to produce cAMP
GTP protein
cholera activates
t/f cholera toxin is a reversible modification
true
rehydration therapy exploits SGLT1 (sodium glucose transporter 1) is used for absorption, how many molecules are transporter? does water transport
2 Na
1 glucose
yes water
effect of opiods on alimentary tract 5
inhibition of enteric neurons (hyperpolarisation)
decreased peristalsis (incr segmentation - constipation)
incr fluid absorption
constriction of sphincters
incr tone of large intestine
list 3 opiod agonists used in diarrhoea
codeine
diphenoxylate
loperamide (most common)
