Gastric Motility and Pancreatic Function Flashcards
Why does no mixing occur due to peristaltic waves in the body of the stomach
The presence of thin muscle, mean only a weak contraction occurs
How does thorough mixing occur in the antrum of the stomach due to peristalic waves
Peristalic waves occur and cause the pyloric spinchter to contract
therefore encourages mixing of contents while only a small amount of chyme enter duodenum to then be forced back up by spinchter for further mixng
What generates peristaltic waved
Pacemaker cells found in the longitudinal muscle layer
How is there a basic electrical rhythm of peristaltic waves
Due to spontaneous depolarisation and re-polorisation conducted through the gap junctions in the longitudinal muscle
creating a constant slow wave
How does a contraction occur above peristaltic waves basic electrical rhythm
Further depolarisation occurs above sub threshold inducing AP and causing a contraction
What two things increase the level of contractions in the stomach
Gastrin
Distension of stomach wall -
What inhibits contractions in peristaltic waves
Fat/acid/amino acid/hypertonicity in duodenum decreases gastrin production therefore decreases motility
How does the distension of the stomach wall increase the level of contraction
Distension stimulates Long/short reflex via vagus nerve
releasing ACH to stimuli above sub threshold
What is secreted from Brunners glands found in the submucosa of the duodenum
Bicarbonate
What is the purpose of Bicarbonate secretion
To neutralise the acid in the stomach
What are the two ways bicaboante secretion is stimulates
When acid is present the duodenum
stimulates long/short ENS reflex which triggers the release of bicarbonate
and stimulates the release of secretin which triggers the release of bicarbonate
How is there a negative feedback control in acid neutralisation
Once acid has been neutralised it feedback and inhibits secretin release
What does the hormone secretin do
Decreases acid secretion
Increase Bicarbonate secretion
Decreases gastric emptying time
Where is secretin secreted from
S cells
What is present in the endocrine portion of the pancreas
Pancreatic inlets - Islets of langerhan
What is Secreated by the islet of langerhan
Insulin (alpha)
Glucagon (beta)
Somatostatin
What is the function of somatostatin
Controls the secretion of insulin and glucagon
What cells are present in the exocrine portion of the pancrease
Accinar cells that come together to from lobules
Duct cells
What do accinar cells come together to fuse and how are the connected
Lobules connected via intercalated ducts
How does the lobules feed into the main pancreatic duct
Intercalated ducts feed into intralobular duct which then feeds into interlobular, which then feed into the main pancreatic duct
What fuses with the main pancreatic duct before entering the duodenum
Bile duct
How does the main pancreatic duct enters the duodenum
enters via the hepatopancreatic ampulla - spinchter of oddi
If the pancreatic duct no longer works how does it feed into the duodenum
through the accessory pancreatic duct
What kind of cells are the duct cells in the pancreas
cubodial
What is the function of accinar cells
Secretes digestive enzyme
What is the function of duct cells
secreate bicarbonate
How does the digestive enzymes not autodiggest the pancreas
Are stored in inactive form called zymogen granules
How are digestive enzymes converted to active form
Due to membrane bound enterokinase converting trypsinogen to trypsin and trypsin further converting inactive enzymes to active from
Where is enterokinase found
On the membrane of the duodenum
What hormone stimulates the release of inactive digestive enzymes (zymogen) from the pancreas
Cholecystokini
When is cholecystokinin released
Released un the response of organic nutrients e.g. fat or amino acids in duodenum
When is cholecystokini released under neural control
Due to parasympathetic innervation through the vagal nerve and local reflexes
Name the 6 pancreatic enzymes
Proteases
Elastases
Nucleases
Phospholipases
α-Amylase
Lipases
PEN PAL
What is the function of protease
Cleave peptide bonds
What is the function of nuclease
Hydrolyse DNA / RNA
What is the function of elastase
Collages digestion
What is the function of Phospholipases
break down phospholipids to fatty acids
What is the function of lipase
Break down of Triglycerides to fatty acids+ glycerol
What is the function of α-Amylase
Breakdown of starch to maltose and glucose
Where is all the places that secrete bicarbonate stimulated by secretin
Duodenal - brunners glands in submucosa
Pancreatic - duct cells
Bile duct
