GI 2 Flashcards
What are the 3 actions of the myenteric plexus?
- tone of gut wall
- rhythmic contraction
- rate of contraction
What are the pacemaker cells of the enteric nervous system?
interstitial cells of Cajal
The slow wave is potentiated by what channel?
sodium channels
the spike potentials are d/t what channel?
calcium channels
What factors increase excitability of the ENS?
- increased stretch/distension
- Parasympathetic Stimulation via Ach
What are the effects of the parasympathetic and sympathetic nervous system on motility?
- sympathetic = decreases motility
- parasympathetic = increases motility
What are the 3 prevertebral reflexes and what are their effects?
- gastrocolic = filling stomach causes defecation
- enterogastric = filling colon closes pyloric sphincter
- colonoileal = colon distention closes ileocecal valve
What is the effect of pain on GI motility?
pain decreases GI motility
What are the 2 suspected causes of IBS?
- anxiety/depression
- Post-infectious IBS (d/t acute gastroenteritis)
Where is the site of secretion of gastrin?
G cells (antrum of stomach)
Where is the site of secretion of CCK?
I cells (duodenum and jejunum)
Where is the site of secretion of secretin?
S cells (duodenum)
Where is the site of secretion of GIP?
K cells (duodenum and jejunum)
What are the 2 actions of gastrin?
- increase gastric acid secretion
- increase stomach muscle contraction rate/force
- increase growth of gastric mucosa
What are the 3 actions of CCK?
- inc gallbladder contraction –> eject bile
- relax sphincter of Oddi
- inc pancreatic enzymes & HCO3- secretion
- inc growth of exocrine pancreas
- inc small intestine contraction
result = bile ejection + slows gastric emptying
What is the action of secretin?
- blocks gastrin effects ->inhibit gastric contraction
- inc pancreatic and biliary HCO3- secretion
Which of the gastric hormones blocks gastrin effects?
secretin