Insulin helps with homeostasis of what?
Blood glucose concentration
What is the normal blood glucose concentration?
What cells in the pancreas produce insulin?
What cells in the pancreas produce glucagon?
The majority of pancreatic cells are acinar cells which secrete ___ enzymes.
Where specifically in a beta cell is insulin produced?
The precursor of insulin is a large chain polypeptide called ___.
What activates insulin?
Cleavage of C peptide which is found in the middle of preproinsulin
Which bonds connect the two polypeptide chains of activated insulin?
Which structure connect the two polypeptide chains for inactive proinsulin?
Depending on the position of amino acids, insulin can be ___-acting or ___-acting.
Which type of insulin acts ultra-quickly and is injected by T1 diabetics 15 minutes before meals?
Which type of insulin acts over an ultra-long period and is injected by diabetics at bedtime to maintain their blood glucose level overnight?
What activates the secretion of insulin by beta cells?
Presence of glucose
By which transporter do glucose molecules enter beta cells?
Within beta cells, glucose is phosphorylated by ___ to form what?
In Type 1 diabetes, what happens to beta cells?
Destroyed by immune system
In Type 2 diabetes, why does insulin resistance develop?
Beta cells fail to sense glucose because they are constantly surrounded by it (hyperglycaemia), no longer produce insulin
What is produced by the metabolism of one molecule of glucose?
36 ATP molecules
When ATP is produced in a beta cell, what happens to
a) Potassium channels
b) Calcium channels
K+ channels close
Beta cell depolarises
Ca2+ channels open
Triggers secretion of insulin by exocytosis
Beta cells release insulin in response to blood glucose concentration rising above __ mM.
In hyperglycaemia, the blood glucose concentration is (below / above) the KM of glucokinase.
What does this cause?
above KM of glucokinase
Over time, Type 2 diabetes:
hyperglycaemia > hyperinsulinaemia > insulin resistance > hyperglycaemia causing complications via Poyol pathway in a vicious cycle
Release of insulin occurs in ___ phases.
What percentage of insulin vesicles are immediately available for release from beta cells?
The other 95% of insulin is released in the (first / second) phase of insulin release.
What type of drug mimics ATP to depolarise beta cells and trigger insulin release?
-amides and -azides
What channel do suphonylurea drugs bind to?
cause them to close - depolarisation due to lack of K efflux - Ca influx - insulin release
What drug has the opposite effect on potassium channels to sulphonylamides and is used to treat functional tumours like insulinomas?
Mutations in the genes for the potassium channels of beta cells can lead to what type of diabetes?
What drug is used to treat this?
Neonatal / congenital diabetes
What disease is caused by mutations affecting beta cell function and presents like T2 diabetes i.e problems with insulin secretion in young people?
maturity-onset diabetes of the young