Gastric motility and pancreatic function Flashcards
Does mixing happen in the body or antrum of the stomach?
antrum
Explain the differences in muscle and contractions in the body and antrum of the stomach
body - thin and weak
antrum - thick and strong
What are 2 consequences of the pyloric sphincter contracting?
small amount of content enters the duodenum
contents not gone through are pushed back up and causes a further mixing of antral contents
What is chime?
liquid slurry
What is the peristaltic rhythm generated by and how many occur in a minute?
3
pacemaker cells
Where are the pacemaker cells found in the stomach?
Longitudinal muscle layer and particularly in the top portion of the stomach
What are slow waves?
random depolarisation and repolarisation which are driven by the pacemaker cells
What is the basic electrical rhythm of the gut?
The slow wave rhythm
How does the BER travel?
along the longitudinal muscle layer through gap junctions
What determines the strength of contraction?
Frequency of action potentials
What 2 things increase the force of contraction?
Gastrin and wall distension
What 4 things inhibit motility?
acid, hypertonicity, fat, amino acid
anything signalling the stomach is emptying
What cells secrete bicarbonate?
brunners glands - submucosal glands
What 2 things promote bicarbonate secretion?
vagal + ENS reflex
secretin
Where is secretin produced?
S cells in the duodenum
Where is bicarbonate secreted from (organ)
pancreas and liver
What mechanism is secretin production controlled by?
negative feedback
Name the 3 parts of the pancreas
head, body and tail
Give the relative anatomical positions of the head and tail of pancreas
head - in curve of duodenum
tail - to the spleen
What makes up the exocrine part of the pancreas?
acinar cells and lobules
What does the endocrine part of the pancreas secrete?
somatostatin to control the secretion of the other 2 compounds released - insulin and glucagon to control blood glucose
Why is there an accessory pancreatic duct?
in case of blockage can still get the secretions into the duodenum
Describe the make-up of the exocrine pancreas
acini cells make up individual lobules
Each lobule has an associated intercalated duct
Many intercalated ducts form an intralobular duct
Many intralobular ducts form the interlobular ducts which lead to the pancreatic duct
How does the pancreatic duct enter the duodenum?
joins with the common bile duct to enter via the sphincter of Oddi
What portion of the pancreas is digestion concerned with?
exocrine
What do the duct cells secrete?
bicarbonate
What do the acini cells secrete?
digestive enzymes
How are the digestive enzymes stored in the acinar cells? Why?
As zymogens
to prevent autodigestion of the pancreas
What enzyme controls the conversion of all other zymogens?
trypsin from trypsinogen
How is trypsin formed?
from trypsinogen due to the enterokinase bound to the brush border of the duodenal enterocytes
Give an example of some pancreatic enzymes and their roles
proteases- break down protein, nucleases-break down DNA, elastases-break down collagen, phospholipases-phospholipid–>FA, lipases-TAG–>FA and glycerol, alpha amylase - starch/glycogen–>maltose +glucose
What stimulates secretin production and what does secretin do?
acid in duodenum
stimulates bicarbonate secretion from pancreas
What stimulates CCK production and what does CCK do?
fat/amino acids in duodenum
zymogen release from acinar cells
What stimulates neural control of pancreas?
organic nutrients in the duodenum
