Gastric Motility and Pancreatic Function Flashcards
What part(s) of the stomach is the mixing of it contents done
Antrum
How is chyme moved through the stomach from body to Antrum
peristaltic waves
What are two functions of the pyloric sphincter
Prevent dumping large amounts of chyme into the duodenum
Generates further mixing with its squeeze effect
What cell type generates the peristaltic rhythm in the stomach
Pace maker cells (cajal cells)
Where are the pacemaker cells in the stomach located
In the longitudinal smooth muscle layer
What is the slow wave pattern set up by the pace maker cells called
The basal electric rhythm (BER)
What ions are responsible for the generation of the BER
Sodium leaking in and potassium leaking out
How does the BER conduct through the stomach cells
Through gap junctions along the longitudnal muscle layer
Is the basal electric rhythm threshold or subthreshold
Sub-threshold
What stimulus is needed to bring the BER above threshold
Mechanoreceptors respond to distension of stomach wall Chemoreceptors in the stomach activate in response to food
Gastrin is released
These all trigger the action potential
What determines the strength of peristaltic contraction in the stomach
The number of action potential generated from Mechanoreceptors and chemoreceptors in the stomach in response to food
What changes the frequency of the BER
It doesnt change
What inhibits the peristaltic movements of the stomach
Fat/Acid/Amino Acid in the duodenum
Hypertonicity in the the duodenum
What does the PH of the duodenum need to be in order for the digestive enzymes to work
7
How is a Ph of 7 achieved in the duodenum
through the release of bicarbonate from brunners glands
What hormone regulates the release of bicarbonate
Secretin
What histoligical layer are brunners cells found
Submucosa
What reflex(s) regulates the release of bicarbonate from brunners glands
Vagal (long and ENS (short) reflexes
What causes secretin production to stop
When no acid is detected in the duodenum
Where does secretin trigger the release of bicarbonate from
Pancreas and liver
What are the two active portions of the pancreas called
The endocrine portion
The exocrine portion
What is the endocrine portion of the pancreas called
The islets of langerhaans
What do the islets of langerhans produce
Insulin, glucagon and somatostatin
What specific cell type produces insulin in the pancreas
B cells
What specific cell type produces glucagon in the pancreas
A cells
What does somatostatin do?
it regulates the production of insulin and glucagon
What is the exocrine portion of the pancreas made up of
Aciner cells and lobules
What is the function of the exocrine portion of the pancreas
It has a digestive function
It produces the enzymes responsible for digestion
What do the acinar cells of the pancreas secrete
Digestive enzymes
What do the duct cells of the pancreas secrete
Bicarbonate
In what state are the enzymes released from the acinar cells of the pancreas
As zymogens
How are the zymogens activated after leaving the pancreas
Enterokinase converts trypsinogen to trypsin
Trypsin then converts all the other zymogens to active forms
Where is enterokinase found
Bound to the brush border of duodenal enterocytes
Name 6 enzymes types that are released from the acinar cells of the pancreas
Proteases Nucleases Elastases Phospholipases Lipases A-amylase
What do proteases do
cleave peptide bonds
What do Nuclease enzymes do
Hydrolyse DNA/RNA
What do Elastase enzymes do
Break down connective tissue
What do phopspholipase enymes do
Break down phopholipids to fatty acids
What do lipase enzymes do
break down triglycerides to fatty acids
What do a-amylase enzymes do
Breaks down starch to maltose and glucose
What triggers the release of digestive stuff from the pancreas
Acid in the duodenum
CHO/Fat in the duodenum
How does Acid in the duodenum trigger the release of bicarbonate
Acid triggers the releases of secretin from S cells.
Secretin then triggers bicarbonate release from the pancreas and liver (duct cells)
How does CHO/Fat in the duodenum trigger the release of enzymes from the pancreas
CHO/Fat in the duodenum triggers the release of CCK.
CCK causes zymogen release from the pancreas
Where is CCK released from
The duodenal mucosa
What effects does CCK have on the digestive tract
Enzyme secretion from pancreas
Relaxation of sphincter of Oddi
Bile release via contraction of gall bladder
