The endocrine pancreas

Question 1

What is the embryology of the pancreas?

Answer 1

At junction of foregut and midgut 2 pancreatic buds (dorsal and ventral) are generated and eventually fuse to form the pancreas
Exocrine functions begin after birth
Endocrine (hormone ) functions from 10-15 weeks

Question 2

Which two buds fuse to form the pancreas in the embryo?

Question 3

What small clusters make up the pancreas?

Answer 3

Formed of small clusters of glandular epithelial cells
98%-99% of cells are clusters called acini

Question 4

How is the exocrine activity of the pancreas performed?

Answer 4

Acinar cells
They manufacture and secrete fluid and digestive enzymes, called pancreatic juice, which is released into the gut

Question 5

How is the endocrine activity of the pancreas performed?

Answer 5

By islet cells
Manufacture and release several peptide hormones into the portal vein

Question 6

How much of the pancreas is the islets of Langerhans?

Answer 6

only 2-3% of total volume of the pancreas

Question 7

What are the different cells in the Islets of Langerhans and what do they secrete?

Answer 7

a-cell secretes glucagon
b-cell secretes insulin
d-cell secretes somatostatin

Question 8

What is insulin?
What is its function?

Answer 8

Polypeptide, 51 amino acids
Reduces glucose output from the liver
Increases storage of glucose, fatty acids, amino acids

Question 9

What is glucagon?
What is its function?

Answer 9

Peptide - 29 amino acid
Mobilises glucose, fatty acids, amino acids from stores

Question 10

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Question 11

What does insulin supress?

Question 12

What does insulin increase?

Question 13

What does glucagon increase?

Question 14

What does glucagon reduce?

Question 15

What are other counterregulatory hormones the have similar effects to glucagon?

Question 16

Describe mechanism behind insulin secretion?

Answer 16

Glucose enters b-cell by GLUT2 glucose transporter

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Question 17

What is insulin released as initially?

Answer 17

Proinsulin
A and B chains of insulin joined by a C-peptide
Disulphide bridges link A and B chains
presence of C peptide implies endogenous insulin production

Question 18

What is biphasic release of insulin?

Answer 18

B-cells sense rising glucose
First phase response - rapid release of stored product
Second phase response - slower, release of newly synthesised hormone

Question 19

What action does insulin have in muscle and fat cells?

Question 20

What are the numeric boundaries of a normal blood glucose?

Answer 20

> 6(mmol/mol) too high
~5 is normal
<4 too low

Question 21

What is the short term response to blood glucose of >6?
What is the long term response?

Answer 21

Make glycogen (glycogenesis)

Make triglyceride (lipogenesis)

Question 22

What is the short term response to a blood glucose of <4 mmol/mol?

What is the long term response?

Answer 22

Split glycogen (glycogenolysis)

Make glucose from amino acids/lactate (gluconeogenesis)

Question 23

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Question 24

What is CHO metabolism?

Answer 24

Metabolism of carbohydrates

Question 25

Best way to eat a meal?

Answer 25

Chatting with family or friends over a meal - feel fuller quicker from smaller portions

Question 26

What are insulins most important mechanisms?

Answer 26

Getting glucose out of the bloodstream
Letting the body know it doesn’t have to produce MORE glucose - e.g. doesn’t have to produce ketones

No hepatic insulin effect - unrestrained glucose + ketone production - more glucose enters the blood

No muscle/fat insulin effect? - impaired glucose clearance + muscle/fat breakdown - less glucose enters peripheral tissues

Question 27

How is CHO metabolism regulated during fasting?

Answer 27

Glucose from the liver - glycogenolysis, gluconeogenesis
Glucose delivered to insulin independent tissues - brain and red blood cells
Insulin levels low
Muscles use free fatty acids for fuel