Insulin Secretion Flashcards
Is the insulin receptor a G-protein coupled receptor?
A. Yes
B. No
B. No - The insulin receptor is a tyrosine kinase receptor.
What is the name of the transporter that allows glucose entry into muscle? A. Glut1 B. Glut2 C. Glut3 D. Glut4
D. Glut4 is the transporter that allows glucose entry into muscle
Where is the Glut2 transporter found?
In beta-cells
What impact does glucagon have on glycolysis?
Glucagon inhibits glycolysis. Glucagon is aiming to raise your blood glucose levels, so you don’t want glucose to be metabolised so glycolysis is inhibited.
What component of the beta-cells sets the threshold for glucose stimulated insulin secretion? A. Glut2 B. Glucokinase C. Krebs Cycle D. K+ATP channel
B. Glucokinase sets the threshold for glucose stimulated insulin secretion.
Beta-cells have Glucokinase rather than Hexokinase. It will only start to form glucose-6-phosphate from glucose when the glucose levels are above the normal range.
Glucokinase has a lower affinity for glucose?
A. True
B. False
A. True
What action does increasing ATP levels have on the K+ATP channels in beta-cells? A. Opens B. Closes C. Translocates D. Lyses
B. Closes
Is glucose the only molecule that modulates insulin secretion?
A. Yes
B. No
No. Glucose is not the only molecule that can moderate insulin secretion.
Fatty acids, Amino acids, GLP-1 and nervous innervation can.
Which second messanger does GLP-1 increase in beta-cells to promote insulin secretion? A. FA-acyl CoA B. Gsq C. IP3 D. DAG E. cAMP
E. cAMP
How do fatty acids stimulate insulin secretion? A. By increasing DAG B. By increasing ATP C. Binding to GRP40 D. All of the above
D. All of the above
Which one of these transcription factors is NOT present in adult beta-cells? A. PDX-1 B. HNF1b C. NeuroD1 D. Nkx6.1
B. HNF1b
What are the characteristics of Type 1 diabetes?
Young age onset Sudden onset Thin Immune Genetic Family history Insulin deficient Ketoacidosis
When might you suspect a diagnosis of Type 1 diabetes in children might not be correct?
A diagnosis of diabetes before 6 months (<1% Type 1)
Family history of diabetes with a parent affected (2-4% Type 1)
Evidence of endogenous insulin production outside the ‘honeymoon’ phase (after 3 years of diabetes) with detectable C peptide (>200nmol/l) when glucose > 8 mmol/l . (1-5% Type 1).
When pancreatic islet autoantibodies are absent, especially if measured at diagnosis (3-30% Type 1).
What are the characteristics of Type 2 diabetes?
Long duration – months or years
Older at diagnosis: 50’s and 60’s
Overweight/obese
Strong family history
Thirst, hunger, polyuria (symptoms of high glucose)
Oral and vaginal thrush; periodontal disease
Tiredness, sleepiness, change of behaviour
Diabetes defining complications:
Microvascular disease - Retinopathy, nephropathy, neuropathy or foot ulcers
Macrovascular disease – Myocardial infarction, stroke, peripheral gangrene
When might you suspect a diagnosis of Type 2 diabetes in adults might not be correct?
Not markedly obese or diabetic family members who are normal weight (20% Type 2)
Acanthosis nigricans not detected (10% Type 2)
Ethnic background from a low prevalence Type 2 diabetes race e.g. European Caucasian (0-45% Type 2)
No evidence of insulin resistance with fasting C peptide within the normal range (0-20% Type 2)
In monogenic diabetes >80% of cases a molecular genetic diagnosis can be made by DNA testing
