Gastric motility and pancreatic function Flashcards
How is foodstuff moved in the stomach?
Using peristaltic waves
What are the differences between the muscle contractions in different parts of the stomach?
How is this relevant to mixing?
In the body, the muscle is thinner and contractions are weaker. Peristalsis moves stuff towards the antrum.
In the antrum; muscle is thicker and contractions are stronger. This allows mixing to take place.
What does the pyloric sphincter do?
Controls exit from the stomach. Only small amounts of Chyme (stomach contents) make it into the duodenum before it closes again.
It also forces chyme back into the antrum which means more mixing takes place.
How frequent is peristaltic rhythm in the stomach?
3 /min
(roughly)
What controls the rate of peristaltic contractions?
Pacemaker cells in the longitudinal muscle layer
Where is the peristaltic contraction conducted to?
Depolarisation carried from the stomach through the intestines through gap juntions in the longitudinal muscle layer
What is the name given to the basic electrical rhythm (BER) that is in the stomach?
Slow wave rhythm
What determines the strength of peristaltic contraction?
The number of Action potentials per wave
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What causes increased motility in the stomach?
Gastrin
Distension of stomach wall
^basically just parasympathetic stim
What inhibits/reduces stomach motility?
Fat/acid/amino acid/hypertonicity in duodenum
(sphincter stays shut)
How is acid in the duodenum neutralised?
Bicarbonate (HCO3-) secretion from Brunner’s Gland duct cells (submucosal glands)
Produces H2O and CO2
How is bicarbonate secretion stimulated when there is acid in the duodenum?
Vagal (long) and Enteric (short) reflexes trigger HCO3- release from Brunner’s glands
Secretin release:
Acid causes S cells to release Secretin. This stimulates HCO3- secretion from the pancreas and liver. As acid is neutralised, secretion decreases accordingly (negative feedback)
The pancreas has an endocrine function and an exocrine function
What does the endocrine portion do?
Insulin
Glucagon
Somatostatin
(secretes this into blood)
What does the exocrine portion of the pancreas do?
Produces/secretes:
Bicarbonate (HCO3-)
DIgestive enzymes (amylase etc)
(into duodenum via ducts)
What anatomical part of the pancreas carries out the endocrine function?
Insulin, glucagon, somatostatin produced by specific cells in Islets of Langerhans
Glucagon - produced by Alpha cells
Insulin - “ Beta cells
Somatostatin - “ delta cells