Gastric Motility and Pancreatic Function Flashcards
What does gastric motility allow for?
Moving food from the upper part of the stomach to the pyloric spincter.
Describe the muscle and force of contraction from the body of the stomach.
Thin muscle so weaker contraction
Describe what is meant by a peristaltic wave.
Contractions which help to move the food from the body of the stomach to the antrum.
Describe the muscle and force of contraction from the antrum of the stomach.
Thick muscle, three layers so much stronger contraction.
Name the three layers of the muscle of the antrum of the stomach.
Circular muscle
Longitudal muscle
Oblique muscle
Which part of the stomach does the mixing of food occur?
Antrum
What does the contraction of the pyloric sphincter help with?
Control of passage of food from the stomach to the duodenum
What is the name given to the gastric content entering the duodenum?
Chyme
What would happen if too much food entered the duodenum at once?
Denature the digestive enzymes of the duodenum as the food would be very acidic and would shock the neutral/alkaline conditions of the duodenum.
Also, there would not be enough bicarbonate in the duodenum to neutralize the HCl
What is the usual peristaltic rhythm?
Three waves/ min
Where are the peristaltic waves generated from?
Pacemaker cells in the longitudal muscle layer
What do the slow peristaltic waves cause to happen?
Spontaneous depolarisation and repolarisation
How are the slow waves conducted from one muscle layer to another?
Via gap junctions
The slow-wave depolarisation is sub-threshold. What is meant by this?
It is not enough to evoke an action potential so further depolarisation is required for an action potential.
How can there be further depolarisation?
Using chemicals or mediators
Give some examples of mediators which help with the depolarization.
Acetylcholine
Gastrin
What determines the strength of contraction?
The number of action potentials
Alongside the spontaneous pacemaker cells, what else is required for a motility?
Neural and hormonal control
What may inhibit the motility in the duodenum?
Fat/acid//amino acid/hypertonicity in the duodenum
Where is the bicarbonate in the duodenum secreted from?
Submucosal glands known as Brunner’s Gland Duct cells
What is the pancreatic head surrounded by?
The C-shaped duodenum
Which organ is the tail of the pancreas close to?
The spleen
Which type of gland is the pancreas?
Mixed- endocrine and exocrine
RECAP- what is meant by endocrine?
Releases hormones or chemicals directly into the bloodstream
RECAP- what is meant by exocrine?
Releases substances through ducts onto the surfaces of the body
What do pancreatic islets (or islets of Langerhan’s) produce?
Insulin
Glucagon
Somatostatin
What do the alpha cells of the islets of Langerhan’s produce?
Glucagon
What do the beta cells of the islets of Langerhan’s produce?
Insulin
What does insulin and glucagon help with?
Levels of blood glucose
What does somatostatin do?
Controls the secretion of insulin and glucagon
Which is the anti-insulin horome?
Glucagon
(When the glucose is GONe)
Which hormone increases blood glucose levels?
Glucagon
Which hormone decreases blood glucose levels?
Insulin
(think, someone would take insulin when their blood sugar is too high).
Which cells are in the exocrine portion of the pancreas?
Acinar cells
Why is part of the pancreas considered to be exocrine:?
It releases enzymes and hormones into the GIT and the GIT is considered to be outside the body
What are the lobules of the pancreas connected by?
Intercalated ducts
What’s the role of the Sphineter of Oddi?
Controls the release of the bile and the pancreatic juices from the common bile duct.
Which part of the pancreas is responsible for digestion?
Exocrine part
Which cells produce the pancreatic juices for the digestion in the pancreas?
Acini cells
Which cells in the pancreas produce bicarbonate?
Duct cells
How are digestive enzymes stored in acinar cells?
As inactive enzymes- inactive zymogen granules
Why are the digestive enzymes in the pancreas stored in zymogen form?
To prevent autodigestion
What is trypsinigen?
An inactive enzyme which can be converted to trypsin
Which pH does trypsin work in?
Neutral or slightly alkaline pH
Which pH does pepsin work in?
Acidic pH
Which enzyme converts trypsinogen into trypsin?
Enterokinase
Where would you find the enzyme enterokinase?
Bound to the brush border of the duodenal enterocytes
What does trypsin do after being converted from trysinogen?
Activates other zymogens to active forms
List the categories of pancreatic enzymes
Proteases
Nucleases
Elastases
Phospholipases
Lipases
Alpha amylase
What is the function of proteases?
Cleave peptide bonds
What is the function of nucleases?
Hydrolyse RNA/DNA
What is the function of elastases?
Collagen distension
What is the function of phospholipases?
Degrade phospholipids into fatty acids
What is the function of lipases?
Degrade triglycerides into monoglycerides and fatty acids
What is the function of alpha amylases?
Convert starch to maltose and glucose
What is bicarbonate secretion stimulated by?
Secretin
Why would secretin be released?
In response to acid in the duodenum.
So secretin will go in the blood and stimulate the release of bicarbonate which will neutralise the acid.
What is zymogen secretion stimulated by?
CCK
When will CCK be released?
In response to fat or amino acids in the duodenum.
What is the long reflex in the GIT?
Vagal reflex
What is the short reflex of the GIT?
Enteric NS reflex
Summarise what will happen if there is fat or amino acids in the duodenum.
Increased CCK release
Enterogastrone released which activates zymogens
Enzymes will flow into the small intestine and help w digestion.
