Flashcards in INTEGRATED FUNCTION OF THE GUT Deck (92)
What are the two plexi found within the wall of the GI tract?
Where is the myenteric plexus found in the wall of the GI tract?
Between the longitudinal and the circular layers of the muscle.
What is another name for the myenteric plexus?
What is another name for the submucosal plexus?
What is the main function of the myenteric plexus?
Coordinates gut movement
What is the main function of the submucosal plexus?
What is another name for the mixing process that occurs in the large intestine?
What causes haustral contractions?
Contraction of the taeniae coli
What is the gastrocolic reflex?
Food leaving the stomach to reach the duodenum sets of a reflex which sends a massive intense contraction through the transverse colon and pushes contents into rectum.
What is the role of the pacemaker cells in the stomach?
Set the basic electrical rhythm for contractions - about 3 per minute
How does the mixing of food happen within the stomach?
Contractions push the food down the stomach, however, because the pyloric sphincter is closed, the smaller bits get pushed back up into the body of the stomach, while the bigger bits get squashed and broken up.
What do the force and frequency of contractions in the stomach depend on?
Intrinsic neural activity
Myogenic properties of smooth muscle
Hormones being secreted
Which type of food will empty from the stomach first? Carbohydrate, Fat, Protein
Which type of food will take the longest to empty from the stomach? Carbohydrate, Fat, Protein
What affect do fatty acids have on the pyloric sphincter?
How does osmotic pressure of the contents of the duodenum affect rate of gastric emptying?
Hyperosmotic (very concentrated) chyme activates osmoreceptors in the duodenum that decrease gastric emptying.
What nerves is responsible for allowing the stomach to distend?
Where in the GI tract is the Auerbach plexus not between the circular and longitudinal muscle? Where is it found?
Between the oblique and the circular layers.
Which hormones are released by the duodenum in response to the presence of chyme coming through the pyloric sphincter? What is their function?
Gastric intestinal peptide
All inhibit gastric empyting
Is the small intestine doing anything in the fasting state?
Yes. There are migrating motor complexes that occur every 90-120 mins.
What is the role of the migrating motor complexes that occur in the small intestine during the fasting state?
Move indigestible food such as tomato skins, nuts and sweetcorn
Remove dead epithelial cells
Prevent bacterial overgrowth
Stop colonic bacteria entering the small intestine.
What is the medical term for vomiting?
What are the associated symptoms to vomiting?
How does the body make sure that vomit does not make its way into the nasopharynx?
The soft palate rises to block entry into it
What are the different classes of drug that increase GI tract motility?
Name 2 types of osmotic laxatives and describe how they work.
Lactulose - disaccharide of fructose and galactose which is degraded by bacteria. Monosaccarides ferment to produce lactate and acetate which draw water into intestine.
Saline purgatives - such as magnesium sulphate and magnesium hydroxide. Increases tonicity hence drawing more water into the lumen.
What are the different classes of drug that decrease GI tract motility?
How do the anti-pasmodic drugs work? (They decrease gut motility)
Anti-muscarinics - decrease muscle tone by inhibiting parasympathetic activity
Mebeverine - acts directly on smooth muscle
What is the role of somatostatin?
Inhibits most secreting cells of the GI tract and pancreas.