Physio and Pharma: fluid balance Flashcards
Diarrhoea?
More than 500mL of faecal fluid output per day.
What are the main mechanisms of Na+ absorption in the small intestine?
Na+/glucose and Na+/amino acids cotransporters.
Na travels down its concentration gradient.
Non-infections causes of diarrhoea?
IBD IBS bile salts excess lacatse defficiency anxiety, depression hyperthyrdoidism drugs
What is the mechanism of secretory diarrhoea?
Activation of adenyl cyclase.
by cholera toxin, exotoxin, salmonella, staph aureus, excess bile salts
How does rotavirus cause diarrhoea?
By inhibiting the Na/K/ATPase and causing structural damage to mucosal cells, reducing absorption
What transporter is utilised in the oral rehydration therapy?
SGLT1, the Na+/glucose co-transporter
absorption of Na and glucose promotes water absorption
What do oral rehydration salts contain?
glucose
NaCl
Sodium bicarbonate (corrects acidosis)
potassium chloride
What antimicrobials are used in severe diarrhoa?
Cotromaoxazole (cholera, E coli)
Erythromycin
Ciprofloxacin (broad spectrum)
Doxycycline (Cholera)
When are anti-motility agents used?
For symptom relief of idiopathic exhausting diarrhoea.
Do NOT use in IBD and IBS
How do opiods work?
They decrease motility.
Inhibition of enteric neurons decrease peristalsis, increase fluid absorption, increase constriction of the pyloric, ileocaecal and anal sphincters.
What opioids are used for diarrhoea?
Loperamide
Diphenoxylate
Codeine
Action of Racecadotril?
Prevents the breakdown of endogenous opioids.
Constipation is…
infrequent production of hard stools required straining to pass or a sense of incomplete evacuation.
Purgatives cause…
a fluid evacuation of the bowel.
Laxative dependency?
Excessive use suppresses the natural propulsive movement of the colon.
