Pathophysiology of Diarrhea
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19 terms
Terms | Definitions |
|---|---|
 Two major mechanisms for diarrhea? | Decreased absorption & Increased secretion |
| Most common cause of osmotic diarrhea? | lactase deficiency |
| Major cause of secretory diarrhea? | Increased secretion of electrolytes (cholera, WDHA syndrome) & fluid (celiac sprue; overabundance of crypt cells) |
| What stimuli are associated with secretory diarrhea? | Mucosal/submucosal, Blood hormone, Luminal |
| What cellular signals are mediated by enterotoxins? | cAMP, cGMP, Ca++ |
| How does cholera work? | A subunit enters cell & turns on adenylate cyclase to max levels Turns off NaCl pump |
| Crypt enterocyte mechanism of CT? | cAMP -> CFTR -> Cl secretion |
| Endocrine cell mechanism of CT? | 5HT & PGE2 release -> Activate neural arc (myenteric plexus) -> Neurons release VIP and Ach -> Crypt enterocyte Cl secretion |
| What are some targets of CT? | Cl ion channel (cAMP has a +ive effect) & NaCl transporter (cAMP has a -ive effect) |
| What is a common feature among bacterial toxins in secretory diarrhea? | Stimulate Cl- secretion No morphological damage No impairment of Na-dependant solute transport |
| What is another way of causing secretory diarrhea? | Hormone producing tumors (hormones bind to enterocytes) |
| Causes of inflammatory diarrhea? | Intestinal infections, C. difficle colitis, Inflammatory bowel disease (ulcerative colitis, Crohn's disease), Other Colitides (radiation, ischemia) |
| How is indirect & direct secretion stimulated? | By inflammatory mediators such as myofibroblasts, macrophages, neutrophils, eosinophils, mast cells |
| What are some mechanisms of inflammatory diarrhea? | 1. Stimulated secretion & inhibited absorption 2. Stimulation of enteric nerves causing propulsive contractions & stimulated secretions 3. Mucosal destruction & increased permeability 4. Nutrient maldigestion & malabsorption |
| What are some treatments of acute diarrhea? | Fluid and electrolyte replacement, Pharmacologic agents, Antimicrobial agents |
| What are some ways to stimulate electrolyte & water absorption? | Glucose/amino acids (reduce net secretion) Rice water Opiates and derivatives (helps slow peristalsis) |
| What are the ways that anti-diarrheal medication works? | 1. Increased Intestinal Absorption (Stimulate absorptive processes, Increase absorption through delayed transit) 2. Decreased Secretion (Inhibit active anion secretion and secondary water movement) |
| What are some anti-diarrheal agents? | • Adsorbents, anti-cholinergics (slow down CNS overview of peristalsis) • Opiates and derivatives • Anti-secretory agents |
| What are some future anti-diarrheal drugs? | - "Super" ORS solutions - Probiotics - Oral immunoglobulins - Receptor antagonists - CFTR inhibitors - Zinc |
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