Gastric Motility and Pancreatic Function Flashcards
In which direction do the peristaltic waves run in the stomach?
Body to Antrum
What functions do the muscles in the antrum have?
Mixing and contraction of pyloric sphincter
What produces gastric peristaltic waves?
Peristaltic rhythm (approx. 3/min) is generated by pacemaker cells in the longitudinal muscle layer
What effect does increasing the number of action potentials have on the peristaltic wave?
It increases the strength of contraction but has no effect on the number of waves
What are the neural and hormonal controls of motility?
Gastrin - increases contraction
Long/Short Reflexes - distension of the stomach wall causes increased contraction
Fat/Acid/Amino Acid/Hypertonicity in Duodenum - Inhibition of Motility
What effect does acid in the duodenum have?
It triggers long (vagal) and short reflexes which trigger bicarbonate secretion
Secretin is released from S cells and triggers release of bicarbonate from the pancreas and liver
What part of the pancreas is the endocrine portion?
The pancreatic islets (Islets of Langerhans)
What part of the pancreas is the exocrine portion?
The acinar cells in the lobules
What are the functions of the exocrine pancreas?
Secretion of bicarbonate by duct cells and secretion of digestive enzymes by acinar cells
What is the function of enterokinases and where are they located?
They are found on the brush border of duodenal enterocytes and convert trypsinogen to trypsin
What is the function of trypsin?
Trypsin converts all other zymogens to active forms
What is the function of proteases?
They cleave peptide bonds
What is the function of nucleases?
They hydrolyse DNA/RNA
What is the function of elastases?
Collagen digestion
What is the function of phospholipases?
Phospholipids to fatty acids
