Lecture 8 Gastric Motility and Pancreatic Function Flashcards
What is the difference between the body of the stomach and antrum
Body has thin muscle as there is no mixing and weak contraction. The antrum has thick muscle for powerful contraction
What produces gastric peristaltic waves
Generated by pacemaker cels in longitudinal muscle layer
How are the slow waves in peristalsis conducted
Through gap junctions along longitudinal muscle layer
Describe the depolarisation of slow waves during peristalsis
Slow wave depolarisation sub-threshold that requires further depolarisation to induce action potential
What does the number of APs determine
Strength of contraction
What is the effect of gastrin
Increases contraction
What happens when there is • Fat/acid/amino acid/hypertonicity in duodenum
inhibition of motility- controls acid, osmolarity and nutrients leaving the stomach
Where is Bicarbonate secreted from and what is its role
Brunner’s gland duct cells in the submucosa.
Enzymes from the pancreas do not operate at a low pH so neutralisation is required as well as the duodenum not being protected by a mucous secreting epithelium
What does acid in the duodenum trigger
Long (vagal) & short (ENS) reflexes that cause bicarbonate secretion.
Release of secretin from S cells which act on Brunner’s gland to release bicarbonate
Describe the negative feedback control in bicarbonate secretion
Acid neutralisation inhibits secretin release
Name the 3 parts of the pancreas
Head, body and tail
Where is the head of the pancreas located
Curvature of duodenum
Where is the tail of the pancreas located
Extends to the spleen
What is the role of the endocrine portion of the pancreas
Contain islets of Langerhans which produce insulin and glucagon
What is the role of the exocrine portion
formed of acinar cells which become lobules connected by interacted ducts and follow through to the common bile duct and responsible for digestion
Where does the common bile duct enter the duodenum from
hepatopancreatic ampulla (sphincter of Oddi)
If the bile duct s blocked where can bile enter the duodenum from
Accessory pancreatic duct
What is the function of the exocrine pancreas
- Secretion of bicarbonate by duct cells
* Secretion of digestive enzymes by acinar cells
What is enterokinase
Bound to brush border of duodenal enterocytes and converts trypsinogen to trypsin
What is the function of trypsin
Converts all zymogens to active forms in the duodenum
Name the pancreatic enzymes
Proteases Nucleases Elastases Phosphlipases Lipases Amylase
Role of Proteases
Clean peptide bonds
Role of Nucleases
Hydrolyse DNA/RNA
Role of Elastase
Collagen digestion
Role of Phospholipas
Phospholipids to fatty acids
Role of lipases
Triglycerides to fatty acid and glycerol
Role of amylase
Starch to maltose and glucose
What stimulates the secretion of biarbonate
Secretin
What stimulates the release of secretin
Acid in the duodenum
What stimulates zymogen
CCK
What is CCK released in response to
Fat/amino acids in duodenum
