The Endocrine Pancreas

Question 1

How many islet cells are in the human pancreas?

Answer 1

1 million

Question 2

Which islet cells secrete insulin?

Answer 2

Beta cells

Question 3

Which islet cells secrete glucagon?

Answer 3

Alpha cells

Question 4

Which islet cells secrete somatostatin?

Answer 4

Delta cells

Question 5

Which islet cells secrete pancreatic polypeptide?

Answer 5

PP cells

Question 6

Which islet cell secretes ghrelin?

Answer 6

Epsilon cell

Question 7

What is the value for basal blood glucose level?

Answer 7

< 5.5mM

Question 8

How many secretory granules are present on the beta cell?

Answer 8

10000

Question 9

How many secretory granules are released per beta cell per day?

Answer 9

<1000

Question 10

How much insulin is in each secretory granule?

Answer 10

8fg

Question 11

What do the beta cells respond to in order to determine the correct amount of glucose for secretion?

Answer 11

Nutrients - amino acids, free fatty acids, glucose
Hormones - IL6, Leptin, Adiponectin, IGF1, Glucagon, GLP1, GIP
Neurotransmitters - Acetylcholine

Question 12

What is the relationship between insulin sensitivity and insulin release in type 2 diabetes?

Answer 12

As insulin sensitivity decreases, insulin release does not increase to match.

Question 13

What is meant by plasticity in beta cell function?

Answer 13

This is the ability of beta cells to adjust to the body’s demand for insulin

Question 14

What is meant by biphasic insulin secretion?

Answer 14

In non-diabetics, there are two phases of insulin secretion - 1st phase when the insulin comes for RRP and the 2nd phase when it comes form stores.
In T2DM, the separation of these two phases is lost

Question 15

How do alpha cells sense glucose?

Answer 15

1. When glucose levels are low, the KATP channels will be partially open.
2. The voltage gated sodium channels then partially open to contribute to the action potentials.
3. There is then opening of calcium channels to cause calcium influx.
4. This triggers glucagon exocytosis.

Question 16

What is the role of glucagon in glucose homeostasis?

Answer 16

Glucagon is secreted from alpha cells in the pancreas and acts on the liver to stimulate hepatic glucose production. In turn the blood glucose acts on beta cells to secrete insulin which then reduces hepatic glucose secretion. Thus maintaining glucose homeostasis.

Question 17

What happens to glucagon secretion in type 2 diabetes?

Answer 17

Glucagon secretion is dysregulated because of a lack of suppression at high glucose levels. Glucagon will still be secreted in the fed state.

Question 18

What is somatostatin 14 secreted in response to?

Answer 18

Nutrient or hormonal stimulation

Question 19

What is the action of somatostatin 14?

Answer 19

It suppresses beta cell and alpha cell function in a paracrine manner.

Question 20

What does endocrine mean?

Answer 20

Glands that secrete hormones and other products directly into the blood

Question 21

What does exocrine mean?

Answer 21

Glands which secrete their products into ducts through the epithelium

Question 22

What does paracrine mean?

Answer 22

This relates to a hormone that has an affect on adjacent cells

Question 23

What does autocrine mean?

Answer 23

A cell-produced substance that has an effect on the cell by which it is secreted

Question 24

What does juxtacrine mean?

Answer 24

This is signalling that requires the close contact of cells.

Question 25

What is the incretin effect?

Answer 25

Insulin secretion is greater from oral glucose relative to an isoglycaemic IV infusion

Question 26

What type of pancreatic cells secrete GLP-1?

Answer 26

L-cells

Question 27

What is the principle incretin hormone?

Answer 27

Glucagon Like Peptide 1 - it potentiates insulin secretion from pancreatic beta cells

Question 28

What are the anorexigenic (satiety) signal?

Answer 28

Peptide YY

Oxyntomodulin

Question 29

Wh