7.3 The Pancreas, Insulin and Glucagon

Question 1

How long is the pancreas?

Answer 1

15cm

Question 2

Where in the abdomen does the pancreas sit? On what side of the abdomen is the head of the pancreas?

Answer 2

Back of the abdomen. Head is on the right side.

Question 3

What is the structure that connects the pancreas to the duodenum?

Answer 3

Pancreatic duct

Question 4

What percentage of the volume of the pancreas consist of pancreatic islets?

Answer 4

2%

Question 5

What percentage of a pancreatic islet is beta cells?

Answer 5

~70%

Question 6

Where are alpha cells located in a pancreatic eyelet?

Answer 6

Closer to the edges

Question 7

What percentage of a pancreatic islet is alpha cells?

Answer 7

~20%

Question 8

What organ does glucagon primarily target?

Answer 8

The liver

Question 9

Which cells secrete somatostatin?

Answer 9

Delta cells

Question 10

What does somatostatin do?

Answer 10

• Inhibits secretion of insulin and glucagon
• Inhibits gastric secretion

Question 11

Describe the steps of insulin formation from transcription to vesicle

Answer 11

Pre-proinsulin -> proinsulin (by cleavage) -> insulin (golgi apparatus)

Question 12

What type of secretory stimulation prompts beta cells to release insulin?

Answer 12

Humoral (high blood glucose)

Question 13

What structure transports glucose into beta cells?

Answer 13

GLUT-2

Question 14

Draw a diagram of how glucose stimulates insulin secretion

Question 15

Which glucose transporters does insulin cause to become added to the target cell membrane?

Answer 15

GLUT-4

Question 16

Is insulin necessary for insertion of GLUT1/GLUT2/GLUT3?

Answer 16

No

Question 17

What effect does the action of insulin have on protein synthesis?

Answer 17

Increase

Question 18

How does insulin promote storage and utilisation of glucose?

Answer 18

Increases activity of enzymes involved in cellular respiration and glycogen formation

Question 19

Which genes can insulin alter through transcription factors?

Answer 19

• Growth
• Repair
• Cellular development

Question 20

List the actions of insulin when it comes to carbohydrates

Answer 20

1. Faciliates uptake and utilisation of glucose
2. Promotes glycogenesis and inhibits glycogenolysis
3. Promotes conversion of glucose into fatty acids and triglycerides
4. Inhibits gluconeogenesis

Question 21

List the actions of insulin when it comes to fats

Answer 21

1. Increases fatty acid uptake into adipose
2. Increases fatty acid synthesis from glucose in adipose
3. Decreases lipolysis (triglyceride breakdown)

Question 22

List the actions of insulin when it comes to proteins

Answer 22

1. Promotes active transport of amino acids into muscle
2. Increases protein synthesis

Question 23

What are three things that cause alpha cells to secrete glucagon?

Answer 23

1. Low insulin activity
2. Catecholamines (sympathetic stimulation)
3. Low free fatty acids (starving)

Question 24

Describe the actions of glucagon with regards to glucose

Answer 24

• Decreases glycogen synthesis and increases glycogen breakdown in liver
• Maintains hepatic glucose output via gluconeogenesis

Question 25

Describe the actions of glucagon with regards to proteins

Answer 25

• Inhibits hepatic protein synthesis
• Promotes hepatic protein lysis

Question 26

Describe the actions of glucagon with regards to fat

Answer 26

• Promotes fat breakdown and inhibits triglyceride synthesis in adipose
• Enhances ketone production

Question 27

Effects of Diabetes mellitus: micro- and macrovascular damage

Answer 27

• Artherosclerosis
• Hypertension
• Decreased perfusion to certain structures

Question 28

Effects of diabetes mellitus: Peripheral neuropathis and ANS dynfunction

Answer 28

• Impaired cardiovascular reflexes/bladder control
• Distal sensory neuropathy
• Gastroenteropathy (constipation with episodes of diarrhoea)