GI Flashcards
Cephalic phase
- the though, sight, smell and taste of food will stimulate the vagal pathway.
- salivary secretion and excitation of the stomach
- pepsinogen and gastrin will be secreted into stomach.
- stimulating the secretion of HCL and enzymes from pancreatic acinar cells.
Gastric phase
-Vagovagal response
- gastrin and histamine secretion will increase acid production
Intestinal phase
- further breakdown and absorption of nutrients
- amino acids and fatty acids will stimulate the release of CCK and secretin into the small intestine.
- cck will cause contraction of the gallbladder (increase bile secretion) and stimulate acinar cells in the pancreas to secret digestive enzymes.
Purpose of secretin and cck?
CCK= contraction of the gallbladder
Secretin = aids in amplification of bile production of the liver and stimulates the pancreas to release enzymes and bicarbonate to neutralise chyme.
What can CCK and secretin work together to do?
They can act together to inhibit peristaltic movements to allow for proper absorption.
What is the purpose of amylase and saliva mixing with food in the mouth?
They will improve the environment for stomach enzymes and make the food easier to swallow.
It also allows amylase to start digesting carbs.
4 phases of swallowing
Voluntary
Pharyngeal
No name
Oesophageal
Migrating motor complex
Prevent bacterial overgrowth and keeps stomach and intestine clean.
Stimulated by motilin (a hormones released during fasted state)
Segmentation
- Mixing chyme with secretions and mucosa.
- contraction of the circular muscle layer.
Peristalsis
Propels chyme along the small intestine via contraction of the longitudinal smooth muscle
main pancreatic blood supply?
splenic artery (from coeliac trunk)
pancreatic-duodenal arteries (from super mesenteric artery)
endocrine pancreas
islets of langerhans - insulin and glucagon
exocrine pancreas
bicarbonate and enzyme
the bicarbonate is what gives the pancreas its high alkalinity .
what stimulates duct cell secretion from of bicarbonate?
- secretin (increases cAMP levels)
- Ach (increase Ca levels)
how does the Cl-/HCO3- exchanger work?
carbonic anhydrase will catalyse the release of CL- through the CFTR chloride channel, allowing the chloride to re-enter the cell through the Cl/HCO3 channel. this moves bicarbonate out and Cl back in.