Diabetes

Question 1

What stimulates insulin release + what process?

Answer 1

insulin is released due to an increase in calcium ions in the pancreatic beta cells = exocytosis of insulin

Question 2

What receptor is responsible for carrying glucose into cells?

Answer 2

GLUT4 which is a glucose transporter protein that carries glucose into fat and muscle cells

Question 3

what type of receptor is the insulin receptor on cells of the skeletal muscles and adipose tissue?

Answer 3

tyrosine kinase

Question 4

what are the 5 insulin-stimulatory factors?

Answer 4

1. cortisol
2. glucagon
3. high concentration of glucose in the blood
4. high concentration of fatty acids and AA in the blood
5. acetylcholine release from M3 receptors by the parasympathetic NS for digestion

Question 5

What is insulin synthesised from? Explain the process

Answer 5

Insulin is a peptide hormone that is synthesised from preproinsulin that has a leader strand attached to a B, C and A chain. The leader strand will be cleaved to form proinsulin.

Proinsulin has a B, C and A chain that will be cleaved at 2 positions thereby leaving the B and A chains together to be joined by 2 disulphide bonds and form INSULIN. Hence preproinsulin yields INSULIN and a C peptide

Question 6

What inhibits insulin release?

Answer 6

1. Norepinephrine due to sympathetic NS stimulation
2. SOMATOSTATIN -INHIBITORY HORMONE that avoids excessive release of pancreatic hormones

Question 7

What is glucagon?

Answer 7

Glucagon is a catabolic peptide hormone

Question 8

Where is glucagon released from and what are its functions?

Answer 8

Glucagon is released from alpha cells in the Islets of Langerhans in the pancreas in response to a low concentration of glucose in the blood - increases blood glucose through breakdown of glycogen to glucose and fatty acids to AA

Question 9

How is glucagon synthesised?

Answer 9

Glucagon is synthesised from PREPROGLUCAGON which has a leader strand cleaved off to form PROGLUCAGON. This will be further cleaved to make GLUCAGON.

Question 10

How is glucagon stored?

Answer 10

As a granule in alpha cells

Question 11

What regulates glucagon?

Answer 11

glucose

Question 12

What are the glucagon stimulatory neurotransmitters/hormones?

Answer 12

1. Adrenaline - parasympathetic NS from B2 receptors
2. Cholecystokinin - by intestinal cells to stimulate digestion and absorption

Question 13

What are the glucagon inhibitory factors?

Answer 13

1. Somatostatin
2. Increased glucose in the blood
3. Growth hormone

Question 14

On what organ does glucagon mainly act on and why?

Answer 14

Liver, to breakdown stores of glycogen into glucose

Question 15

What type of receptor is the glucagon receptor in cells of the liver, adipose tissue and skeletal muscle?

Answer 15

7 pass transmembrane receptor

Question 16

What AA stimulate glucagon secretion?

Answer 16

Alanine and Arginine

Question 17

What happens after glucagon binds its 7TM receptor?

Answer 17

there is a second messenger of the glucagon receptor, cAMP, which activates protein kinases and leads to enzyme phosphorylation

Question 18

Give an example of an incretin hormone.

Answer 18

GLP-1

Question 19

What is GLP-1?

Answer 19

A physiological incretin hormone

Question 20

How is GLP-1 made?

Answer 20

derived from PROGLUCAGON, similar to GLUCAGON

Question 21

What is the role of GLP-1?

Answer 21

Stimulate insulin secretion and inhibit glucagon secretion = decreased glucose levels in the blood

Question 22

What is the half-life of GLP-1?

Answer 22

1.5-2 min

Question 23

What are the 5 functions of GLP-1?

Answer 23

1. Stimulate insulin secretion
2. Inhibit glucagon secretion
3. Delay gastric emptying
4. Suppress appetite
5. Stimulate pancreatic Islet B cell proliferation