Gastric Motility and Pancreatic Function Flashcards
Where do peristaltic waves travel from and to?
From the body of the stomach to the antrum
What sort of movement is in the body ?
Since the muscle is thin here - contractions are weak
No mixing occurs, movements just pass food along
What kind of movement is there in the antrum?
Thick muscular walls = powerful contractions
Cause mixing
What causes further mixing of the chyme?
Contraction of the pyloric sphincter - only lets a small amount into duodenum meaning rest is pushed back up and mixed further
What is the peristaltic rhythm?
3 per min
What generates these waves?
Pacemaker cells in the longitudinal muscle layer
What is the slow wave rhythm called?
Basic electrical rhythm (bER) - caused by spontaneous depolarisation/repolarisation
What determines the strength of contraction?
Number of APs per wave
What hormone increases contractions?
Gastrin
What reflexes increase contraction?
Distension of stomach wall = long/short reflexes
What inhibits motility of stomach ?
Fat
Acid
Amino acids
Hypertonic solutions
These in the duodenum
What neutralises acid in the duodenum?
Bicarbonate secretion from brunner’s gland duct cells
Where are brunner’s gland duct cells?
In the submucosa
Describe the neural control of duodenal bicarb secretion.
Acid in duodenum triggers a long reflex (vagal) and short reflex (enteric NS) leading to bicarbonate secretion
Describe the endocrine control of bicarb secretion.
Release of secretin from S cells leads to bicarb secretion from pancreas and liver
When acid is neutralised this inhibits secretin release
Describe the shape of the pancreas.
Head - sits in curve of duodenum
Neck
Body
Tail - extends to spleen
What is the endocrine portion of the pancreas?
Contains the pancreatic islets cells/ islets of langerhans
These make several hormones such as insulin, glucagon and somatostatin
What is the exocrine portion of the pancreas responsible for?
Secreting digestive enzymes - duct cells
Secreting bicarbonate - acinar cells
What is the exocrine portion made up of? How do all these connect and feed back to the duodenum?
-Lobules feed into an intercalated duct
-Goes on to an intralobular then an interlobular duct
Interlobular feeds into the pancreatic duct
- Pancreatic duct feeds back towards the head where it anastomoses with the common bile duct
- Then heads towards the duodenum through the sphincter of oddi
What is another duct that feeds directly into the duodenum not through the sphincter of oddi?
Accessory pancreatic duct
Do acinar cells store digestive enzymes?
Yes but in an inactive zymogen form
How are zymogens activated when they enter the duodenum?
Enterokinase is bound to the brush border of duodenal enterocytes
Enterokinase converts trypsinoigen to trypsin
Trypsin converts all other zymogens to active forms
What do proteases do?
Cleave peptide bonds
What do nucleases do?
Hydrolyse DNA
What digests collagen?
Elastases
What turns phospholipids to FFAs?
Phospholipases
What do lipases do?
TAG to FFA + glycerol
What does alpha amylase do?
Starch to maltose + glucose
What stimulates zymogen secretion?
Cholecystokinin - CCK which is released in response to fat/amino acids in duodenum
CCK is also released va vagal/ENS reflexes which are also triggered by arrival of fat/amino acids
