Pancreas

Question 1

describe the structure of insulin

Answer 1

• A chain and B chain are connected by disulfide bonds
• The C peptide (connecting peptide) connects the A and B chain

Question 2

what is the clinical signifiance of C peptide?

Answer 2

Measurement of C peptide is clinically useful to measure the amount of endogenous insulin as it is not metabolized by the liver

Question 3

describe signaling pathway in the pancreatic beta cell

Answer 3

• 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

Question 4

describe the function of insulin on liver

Answer 4

Question 5

describe the function of insulin on muscle cells

Answer 5

Question 6

describe the function of insulin on adipose

Answer 6

Question 7

describe function of glucagon

Answer 7

effect is only on liver

• increases glucose levels by increasing glycogenolysis and gluconeogenesis

Question 8

explain cell signaling of glucagon

Answer 8

increases cAMP

Question 9

describe function of somatostatin

Answer 9

• release stimulated by ingesting food
• actions:
  
  • decrease insulin and glucagon secretion
  • decrease GIT motility
  • decrease secretions and absorption by GIT

Question 10

describe diabetes mellitus (type I)

Answer 10

• 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

Question 11

describe type II diabetes

Answer 11

• 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

Question 12

describe treatments for diabetes

Answer 12

1. sulfonylurea drugs which stimulate insulin secretion
2. biguanide drugs (metformin) which up-regulate the insulin receptors