Endocrine Pancreas Flashcards
What is the function of the endocrine pancreas?
Regulation of metablism
What are islets of Langerhans?
Isolated clumps of cells
Surrounding a capillary
What are the 3 types of islets of Langerhans and what do they secrete?
Alpha - glucagon
Beta - insulin (majority)
Delta - somatostatin
Where do the hormones secured by islets of Langerhans go?
Into blood stream
Pass to liver via hepatic portal vein
When is insulin released?
In response to increase plasma levels of glucose and amino acids
Is insulin anabolic or catabolic?
Anabolic - builds glycogen
Insulin is synthesised as pre prohormone, then converted to proinsulin. How is proinsulin converted to active insulin?
Cleave of c peptide, which makes the proinsulin inactive
How is insulin deactivated? Where?
Cleavage of sulfur bonds
In liver
What is the parasympathetic innervation via for the production of insulin?
Vagus nerve
What happens to insulin during sympathetic activity and release of adrenaline?
Decreased production
How long is the half life of insulin?
5/10 minutes
Where does insulin bind on a cell? What affect does it have?
Receptors
Mobilises GLUT4 to cell membranes to allow glucose to leave cells
Which tissues are insulin independent? How do they control glucose uptake?
Brain, liver, intestines, kidney, mammary glands
Different GLUT transporters
What happens to the kidneys in diabetes mellitus?
Capacity for kidneys to absorb glucose is exceeded
Cats are more prone to which type of diabetes?
Type II
What is type 1 diabetes?
IDDM
Pancreas inflammation, hypersecretion of hormones.
What is type 2 diabetes?
NIDDM
Normal insulin production, but cells resistant to its effect
What does hyperglycaemia cause?
Polyuria
Polydypsia
Artificially high specific gravity due to glucosuria
How can hyperglycaemia lead to metabolic acidosis?
Increased degradation of lipids
Increased fatty acids in plasma
Increased ketone production (some ketones are acidic)
What is hypoglycaemia caused by? How is it treated? Is it common or rare in ruminants?
Insulin overdose or insulinoma (tumour of pancreatic B cells)
Treated by oral or IV glucose
Rare
What is glucagon? Why is it released?
Hormone released in response to decreased levels of glucose and amino acids
What does glucagon stimulate?
Gluconeogenesis
Glycogenolysis
Glucagon is also synthesised as a prepro hormone, like insulin. Where is active glucagon deactivated and how?
Metabolism in liver and kidneys
Where does glucagon bind to cells?
Target receptors
What does the net effect of glucose plasma levels depend on?
Ratio of insulin to glucagon
