Biochemistry Flashcards
What do beta cells secrete?
insulin
What do alpha cells secrete?
glucagon
What do omega cells secrete?
Somatostatin
What do PP cells secrete?
Pancreatic polypeptide
What does insulin contain?
2 poly peptide chains linked by disulfide bonds
How does glucose enter beta cells?
through the GLUT2 glucose transporter, its phosphorylated by glucokinase
What does ATP inhibit?
ATP-sensitive K+ channel K(ATP)
What does inhibition of K(ATP) lead to?
Depolarisation of the cell membrane
What does cell membrane depolarisation lead to?
Opening of voltage-gated Ca2+ channels
What does an increase in internal Ca2+ conc lead to?
fusion of secretory vesicles with the cell membrane and release of insulin
What’s the subunit of inward rectifier subunit (K(IR))?
Kir6.1
What’s the subunit of a sulphonylurea receptor?
SUR1
Loss of insulin secreting beta cells is what type of diabetes?
1
Defective glucose sensing in the pancreas and/or loss of insulin secretion is what?
MODY
Initially hyperglycaemia with hyperinsulinemia so primary problem is reduced insulin sensitivity in tissues is what?
Type 2 diabetes
Describe the insulin receptor?
A dimeric tyrosine kinase
Two extracellular alpha subunits with insulin binding domains
Two transmembrane beta subunits
Linked by disulfide bonds
What happens to beta cells when alpha cells bind to insulin?
They self phosphorylate (autophosphorylation)
What is Leprechaunism (Donohue Syndrome)?
rare autosomal recessive genetic trait
Mutations in gene are for insulin receptor
Severe insulin resistance
What are features of Donohue syndrome?
Elfin facial expression
Growth retardation
Absence of subcutaneous fat, decreased muscle mass
What is Rabson Mendenhall syndrome?
rare autosomal recessive Sever insulin resistance hyperglycaemia, hyperinsulinemia Developmental problems Acanthosis nigricans (hyperpigmentation)
Where are ketone bodies formed?
In liver mitochondria
derived from acetyl-CoA from beta oxidation
When are ketone bodies converted back to acetyl-CoA?
When they renter the TCA cycle
Ketoacidosis is associated with which diabetes type?
1
