Pancreatic Endocrinology

Question 1

What proportion of pancreatic cells are acini?

Answer 1

98-99%

Question 2

What do acini release?

Answer 2

EXOCRINE function.

Secrete digestive enzymes through pancreatic ducts and the ampulla of vata into the small intestine

Question 3

What proportion of pancreatic cells are islets of Langerhans?

Answer 3

1-2%

Question 4

What do the islets of Langerhans release?

Answer 4

ENDOCRINE function.

Secrete peptide hormones into the portal vein

Question 5

Give the cell types of the islets of Langerhans and each hormone that they release.

Answer 5

Delta cells: Somatostatin
Alpha cells: Glucagon
Beta cells: Insulin

Question 6

What are the effects of insulin?

Answer 6

1. Increases glucose uptake into cells in response to high blood glucose levels
2. Decreases glycogenolysis
3. Increases glycogenesis
4. Increases conversion of glucose to fatty acids

Question 7

What is the target cell for insulin?

Answer 7

Hepatocytes and muscle cells

Question 8

What are the effects of glucagon?

Answer 8

1. Increases Glycogenolysis
2. Increases Gluconeogenesis
3. Stimulates lipolysis for respiration

Question 9

What is the target cell for glucagon?

Answer 9

Hepatocytes

Question 10

What is the precursor to insulin?

Answer 10

Proinsulin.

Question 11

Which molecule is not present in synthetic insulin but is in natural insulin?

Answer 11

C peptide

Question 12

Which glucose transporter is present in beta cells?

Answer 12

GLUT2

Question 13

What is the affinity of GLUT2 to glucose?

Answer 13

Low affinity. Only binds when there is a high concentration of glucose.

Question 14

Once inside the beta cell, which enzyme breaks down glucose into glucose-6-phosphate?

Answer 14

Hexokinase

Question 15

Outline the steps of insulin release from beta cells.

Answer 15

1. ATP binds to a K+ ATP channel and closes the channel
2. K+ ions are unable to leave the cell, resulting in depolarisation of the beta cell membrane
3. Voltage gated Ca2+ channels open and Ca2+ ions diffuse into the cell
4. Ca2+ ions bind to insulin secretory granules
5. Granules fuse with the cell membrane and release the insulin via exocytosis

Question 16

Give the steps that follow when insulin binds to insulin receptors on cell membranes of muscles.

Answer 16

1. Signalling cascade is triggered
2. GLUT4 vesicles fuse with the cell membrane
3. Results with a greater rate of glucose diffusion into the cell
4. This decreases blood glucose levels

Question 17

Where are glucose level sensors located in the body?

Answer 17

Islets of Langerhans
Medulla
Hypothalamus
Carotid bodies

Question 18

Which peptides are secreted from endothelial cells in the GI tract in response to eating?

Answer 18

Incretins

Question 19

In a fasting state, where is glucose produced?

Answer 19

Liver via glycogenolysis

Question 20

How much ingested glucose goes to the liver?

Answer 20

40%. 60% goes to muscle.