Insulin Secretion and signalling Flashcards Preview

Endocrinology > Insulin Secretion and signalling > Flashcards

Flashcards in Insulin Secretion and signalling Deck (22):
1

Where is insulin made?

Pancreatic islets

2

What types of cells pancreatic islets and what do they secrete?

beta cells - insulin
alpha cells - glucagon
delta cells - somatostatin
PP cells - pancreatic polypeptide

3

What is the structure of insulin?

2 polypeptidechains
linked by disulfide bonds
connecring (C) peptide

4

How does glucose enter beta cells?

through GLUT2 transporter

5

What happens when glucose enters the beta cell?

Phosphorylated by glucokinase
Increases intracellular ATP
ATP inhibits K ATP channel
Depolarisation
Voltage gated Ca2+ channels open
Vesicles fuse to membrane
Secrete insulin

6

Desribe the two phases of insulin secretion

1st-readily releasable pool
2nd- mobilization

7

What subunits make up the K ATP channel? What inhibits each subunit?

Kir6.2 pore - ATP
SUR1 regulatory - sulphonylurea

8

What stimulates the K ATP channel at the SUR1 subunit?

diazoxide

9

Describe what the defect in MODY

Glucokinase impared
Glucose sensing defect
Increases threshold for insulin secretion

10

What are the three phases of the signalling cascade?

Reception of hormone
Transduction
Cellular response

11

What is the name of the insulin receptor?

Tyrosine kinase

12

Describe the tyrosine kinase receptor

2 alpha subunits
2 beta subunits
disulfide bridges

13

Describe what happens in insulin signalling

Insulin binds to alpha subunits
Autophosphorylation at beta subunits
Insulin receptor substrates phosphorylated
Causes gene expression and glycogen synthesis


14

Describe how glycogen is synthesised

PKB causes GLUT4 to translocate to surface
Glucose into cell

15

What are the biological processes insulin increases?

Glucose uptake
Lipogenesis
Glycogen synthesis

16

What biological processes does insulin prevent?

Lipolysis
Gluconeogenesis in liver

17

What happens in Donohue syndrome (leprachaunism)

insulin resistance
growth abnormlities
elfin features
growth retardation

18

What happens in Robson Mendenhall syndrome?

insulin resistance
hyperglycaemia
compensatory hyperinsulinaemia
leads to: hyperpigmentatoin
DKA hypoglycaemia respone

19

Where are ketone bodies produced?

liver mitochondira

20

When are ketone bodies formed?

fatty acids oxidised in TCA cycle
excess acetyl co-A turned to ketone bodies

21

Name three ketone bodies

Acetone
Acetoacetic acid
Beta-hydroxybutyric acid

22

When is ketoacidosis most common?

Type 1 diabetes