Insulin glucagon and GLOP1 and counter regulatory hormones

Question 1

1. Describe the hormone secreting cells of the pancreas.

Answer 1

alpha- glucagon
- bathed in high levels of insulin, glucagon usually suppressed

Beta- insulin

Question 2

2. Describe structure of insulin and the stimuli that lead to its release.

Answer 2

insulin is released as pro-insulin and its c peptide is cleaved off

Question 3

3. Describe the cellular mechanisms leading to the secretion of insulin in response to an increase in serum glucose.

Answer 3

glucose comes in through a glut 2 transporter, and as it goes through glycolysis the ATP and NADH generated closes off the K+ channel which then depolarizes the cell, causes calcium channel to pen and calcium comes into the cell, casuing release of vesicles with insulin

Question 4

4. Describe the mechanisms for insulin signaling within target cells for metabolic and mitogenic actions.

Answer 4

the insulin receptor is a tyrosine kinase that when activated autophosphorylates, and attracts IRS elements which then activate the P13K–>Akt–> upregulation of glut 4 transporters metabolic pathway or the Map kinase mitogenic pathway

Question 5

5. List the actions of insulin on Muscle, Liver and Adipose tissue.

Answer 5

muscle- causes upregulation of glut 4 to take in glucose
also upregulates glycogen synthase

Liver- increases glycogen formation, Glycolysis, de novo fatty acid synthesis
Adipose-store energy

Question 6

6. Describe in general what insulin resistance is.

Answer 6

there is less upregualtion of glucose 4 transporters in insulin dependent cells to the same insulin concentration

Question 7

7. Describe the incretin effect and list the effects of GLP-1.

Answer 7

GLP-1 which is a product of the proglucagon gene, is released from small intestine in response to meals and it potentiates the insulatin relaese in the presence of glucose

it also lowers glucagon

DPP-4 enzyme inactivates incretins

GLP-1 has many actions outside the pancrease to,

• lowers gastric emptying
• increases cardiac output
• increases insulin sensitivity
• decreases apetite

Question 8

8. List the effects of the counter-regulatory hormones glucacon, catecholamines, cortisol and growth hormone.

Answer 8

they have similar actions to glucagon