Gastric Motility and Pancreatic Function Flashcards
What part of the stomach has the thickest muscle layer and why?
Antrum because this is where the majority of motility occurs
What kind of muscle layer does the body have?
Thin muscle layer for weaker contractions
Does the fundus contain muscle?
Yes, but it is relatively little
How much gastric content (Chyme) enters the duodenum at a time?
Small amounts and as the sphincter contracts the antral contents are pushed back into the body for more mixing
What generates the peristaltic rhythm?
Pacemaker cells found in the longitudinal muscle layer
What does the slow wave rhythm create?
The Basic Electrical Rhythm (BER)
Slow waves due to slow de/repolarisation
How are the fibres connected?
By gap junctions so electrical activity spreads
What does gastrin lead to?
Increased contraction
What does stomach distension lead to?
Long/Short reflexes
Increased contraction
What inhibits motility?
Fat/Acid/Amino Acid/Hypertonicity in the duodenum
What is the other name for submucosal glands that secrete bicarbonate?
Brunner’s Gland duct cells
Why is bicarbonate needed to neutralise stomach pH?
Pancreatic enzymes are denatured at stomach pH so this must be resolved
What does acid in the duodenum trigger?
Bicarbonate secretion via Long (Vagal) & Short (ENS) reflexes and release of secretin from S cells
What does secretin stimulate?
Brunner’s Gland
Where does the acid and bicarbonate come from?
Acid comes down into the duodenum from the stomach
Bicarbonate comes up from the submucosa of the duodenum
What two functions does the pancreas have?
Exocrine
Endocrine
What does endocrine control?
Metabolism
Which cells create Insulin and Glucagon to control blood sugar levels?
Islets of Langerhans
What hormone controls the Insulin and Glucagon levels?
Somatostatin
What are the two functions of the exocrine part of the pancreas?
Aids digestion by secretion of digestive enzymes from acinar cells
Secretion of bicarbonate by duct cells (In response to secretin)
What is found in the exocrine part of the pancreas?
Acinar cells
Lobules
The pancreatic join the bile duct and joins the duodenum where?
Sphincter of Oddi
What opens up if the main pancreatic duct is blocked?
The accessory duct
How are the acinar arranged?
Triangularly to make the gland
What are digestive enzymes stored as inside the acinar cells?
Inactive zymogen granules
What converts Trypsinogen to Trypsin and where is it bound?
Enterokinase
Brush border of duodenal enterocytes
What does Trypsin do?
Converts all other zymogens to active forms
What stimulates zymogen secretion?
Cholecystokinin (CCK)
CCK is also released in response to fat and acid in the duodenum
What type of control is CCK under?
Zymogen - Triggered by the arrival of organic nutrients in the duodenum
Where does CCK come from and what is special about it and Secretion?
Duodenal mucosa
They react synergistically together
What are the 6 types of pancreatic enzymes?
Proteases Lipases α-Amylase Phospholipases - Phospholipids to fatty acids Nucleases Elastases
Where is the H/K pump located for Hydrogen ion secretion?
Cannalicular membrane
What hormone inhibits Gastric Acid secretion?
Somatostatin
