Lecture 12- Endocrine pancreas Flashcards
Pancreas functions?
Two functions
Digestive enzymes exocrine and hormones endocrine
Hormones produced by pancreases?
Insulin, glucagon, ghrelin, somatostatin
What do insulin and glucagon regulate?
Metabolism of carbohydrates, fats and proteins
Plasma glucose levels?
Normally 3.3 to 6 mMol/Litre
Rising to 7-8 after a meal.
At what blood glucose level will you got glycosuria?
When renal threshold exceeds 10 mMol/L
Actions of insulin?
Anabolic
Anti gluconeogenic
Anti lipolytic
Anti ketogenic
How is insulin synthesised?
Made in RER and sent to Golgi where secretory vesicles contain insulin and c peptide.
Vesicles undergo margination as they move to the cell membrane ready for exocytosis
What is the role of KATP channels in insulin release?
When no glucose present channels open and get hyperpolarisation. When glucose present channels close and get depolarisation which is detected by voltage gated calcium channels. These channels open and calcium influx causes vesicles to be exocytosed. High ATP from glucose metabolism in cell shuts channels
What type of receptor is that for insulin?
Tyrosinee kinase
Actions of insulin on cell?
Causes glucose uptake. Leads to glycogen formation as well as pyruvate and fatty acids
Glucagon actions?
Glycogenolytic
Gluconeogenic
Ketogenic
Lipolytic
Insulin nand glucagon both undergo margination, what is it?
Movement of vesicles to cell surface
Where does glucagon have its main effect?
Liver glycogenolysis
Main difference in structure between glucagon and insulin?
Glucagon is rigid insulin is flexible
When is glucagon used clinically?
Diabetic patient with hypoglycaemia cannot take oral glucose
What is ketogenesis?
Producing ketone bodies using fatty acids and ketogenic amino acids
What is diabetes characterised by?
Chronic hyperglycaemia leading to long term clinical complications.
Associated with elevated glucose levels in urine
What glucose levels indicate diabetes?
Fasting glucose of over 7 and random glucose over 11.1
Cause of type one diabetes?
Autoimmune destruction of pancreatic B cells.
Can be absolute where completely destroyed or relative where failure to secrete adequate amounts of insulin
What happens with KATP channels and type 1 diabetes?
Insensitive to ATP so when glucose metabolised and ATP produced channels fail to shut and hyperpolarisation persists which prevents calcium influx and insulin release
Type 2 diabetes cause?
Insulin secreted but peripheral resistance.
Defective insulin receptor
Defect in post receptor events
Excessive glucagon
What causes type 2 diabetes?
Peripheral insulin resistance caused by a combination of genetic factors and environmental factors including obesity and sedentary lifestyle
What happens with insulin resistance in the young?
Initially beta cells compensate. Eventually unable to maintain and finally their dysfunction leads to relative insulin deficiency and overt type 2 diabetes
Overt vs subclinical diabetes.
Subclinical is early stage where glucose tolerance only abnormal with stress. Overt is advanced clinical stage
