Pancreas Flashcards
1
Q
describe the structure of insulin
A
- A chain and B chain are connected by disulfide bonds
- The C peptide (connecting peptide) connects the A and B chain
2
Q
what is the clinical signifiance of C peptide?
A
Measurement of C peptide is clinically useful to measure the amount of endogenous insulin as it is not metabolized by the liver
3
Q
describe signaling pathway in the pancreatic beta cell
A
- GLUT 2 receptor = low affinity
- high amount of glucose = entry through transporter
- Glucose converted into G6P via glucokinase
- G6P oxidized to synthesize ATP
- ATP closes ATP/K channel, high levels of ATP closes channel
- closing of this channel causes intracellular K to rise, depolarizing the cell
- Depolarization causes Ca channel to open causing release of insulin
4
Q
describe the function of insulin on liver
A
5
Q
describe the function of insulin on muscle cells
A
6
Q
describe the function of insulin on adipose
A
7
Q
describe function of glucagon
A
effect is only on liver
- increases glucose levels by increasing glycogenolysis and gluconeogenesis
8
Q
explain cell signaling of glucagon
A
increases cAMP
9
Q
describe function of somatostatin
A
- release stimulated by ingesting food
- actions:
- decrease insulin and glucagon secretion
- decrease GIT motility
- decrease secretions and absorption by GIT
10
Q
describe diabetes mellitus (type I)
A
- insulin-dependent, juvenile onset
- caused by destruction of B cells
- disruption of carbohydrate, lipid and protein metabolism
- increased levels of glucose, FFAs and AAs in blood
- increased ketone bodies (DKA)
- in DKA, H+ ion is exchanged for intracellular K+
- there is K in ECF which is lost in urine
11
Q
describe type II diabetes
A
- late onset, non-insulin dependent
- tissues are insulin-resistant due to down regulation of insulin receptors
- hereditary and obesity are main factors
- these individuals have sufficient insulin and do not develop ketoacidosis
12
Q
describe treatments for diabetes
A
- sulfonylurea drugs which stimulate insulin secretion
- biguanide drugs (metformin) which up-regulate the insulin receptors