Pancreas Flashcards
What is the name of the group of secretory cells? What epithelium is it lined with?
Groups of acini
Simple cuboidal
What is the function of the exocrine and endocrine pancreas?
Exocrine = digestion Endocrine = regulation of metabolsim
What are the two major components of pancreatic juice?
Bicarbonate ions - neutralise stomach acid
Enzymes - digest food material for absorption
When does pancreatic juice remain highly alkaline and why?
At high flow rates e.g. during digestion it remains highly alkaline as there is not enough time for bicarbonate reabsorption
Duodenal epithelial surface contains enteropeptidase, what is the role of this enzyme?
Activates trypsinogen into trypsin, this then activates proteases
What is the intestinal phase of digestion in the pancreas regulated by?
It is the hormonal phase so is regulated by secretin and CCK
What is secretin released in response to and what is its role?
Released from duodenum in response to hydrogen ions
It increases bicarbonate secretion
What is CCK released in response to?
Describe how it works as a positive feedback mechanism
Released from duodenum in response to fat / protein metabolites
- Increased enzyme secretion produce more metabolites which in turn stimulate further CCK release
What is the name of the clusters of cells scattered through pancreatic tissue?
islets of Langerhans
What is insulin released in response to, what is the overall effect of its secretion?
- increased plasma levels of glucose and amino acids
- anabolic effect
How is insulin de-activated in the liver?
Cleavage of di-sulphide bonds
Describe the bi-phasic secretion of insulin
- Initial immediate secretion of stored insulin lasting 5-15 mins
- Followed by more prolonged secretion of newly synthesised insulin adjusted to plasma levels of glucose
Activity of which part of the ANS increases insulin secretion?
Parasympathetic NS
- long reflex arc
How does insulin help to enhance glucose uptake?
Mobilisation of glucose transporter GLUT4 to cell membranes
Where does insulin mostly act to increase the conc of intra-cellular enzymes involved in metabolism?
Liver
Skeletal muscle
Adipose tissue