L27 Regulation Of Glucose

Question 1

What are the other grouped endocrine cells?

Answer 1

1. F or polypeptide cells
2. e cells
3. enterochromaffin cells

Question 2

What are the 3 main islet secretory cells?

Answer 2

1. β (65%)
2. α (20%)
3. Delta (10%)

Question 3

What does the beta and alpha cells of endocrine pancreas secrete?

Answer 3

β cells – insulin (peptide hormone), proinsulin, C peptide, amylin (IAPP)
α cells – glucagon (G) together regulate glucose, FA and AA metabolism

Question 4

What does delta and f cells secrete?

Answer 4

δ cells – somatostatin - regulates hormone release
F (PP) cells – pancreatic polypeptide - decrease exocrine pancreas

Question 5

What does e (epselon) cells produce?

Answer 5

Ghrelin protein - stimulates hunger

Question 6

How does communication and control - humoral happen?

Answer 6

1. Small arteries enter islet core and distribute blood through the fenestrated capillaries.
2. Through vascular arrangement - venous blood of one cell type bathes the others.
3. Richly perfused blood metabollically activate, releases hormone and sense nutrients.

Question 7

How do beta and alpha cells communicate to each other?

Answer 7

Via gap junctions between the cells
Delta cells send dendrite like processes to beta cells

Question 8

What are the islets innervated by?

Answer 8

Adrenergic
Cholinergic
(Peptidergic neurons)

Question 9

What is the mechanism of secretion in the beta cells of pancreas?

Answer 9

1. Secretion happens though a process called GSIS (glucose-stimulated insulin secretion).
2. Glucose enters beta cell through GLUT 1 and is metabolized through glycosis generating ATP.
3. KATP channels close preventing outflow of K.
4. Reduced outflow of K starts depolaristaion in membrane causing opening of the calcium channels.
5. Calcium ion enter and secrete out insulin through exocytosis.

Question 10

How is insulin secretion regulated?

Answer 10

Through the beta cells:
1. High blood glucose stimulate secretion and low inhibits.
2. Neural control
3. Humoral factor like somatostatin and GIP
4. Drugs - Sulphonylureas.

Question 11

How does neural control of insulin regulation takes place?

Answer 11

1. Sympathetic stimulation - increase in beta adrenergic secretion and decrease in alpha adrenergic secretion.
2. Parasympathetic stimulation - increase in acetylcholine release from vagus nerve.

Question 12

Insulin acts via receptors

Question 13

Which body cells are mainly targeted by endocrine hormones?

Answer 13

Liver + muscle tissues are targeted to store glucose as glycogen

Question 13

What is glycogenesis?

Answer 13

Conversion of glucose to glycogen

Question 14

Blood glucose

Question 14

What is lipogenesis?

Answer 14

Excess glucose converted into fat

Question 15

Do insulin have a stimulatory and an inhibitory effect?

Answer 15

Stimulates formation of glycogen from glucose (glycogenesis)
Inhibits glycogenolysis
Inhibits gluconeogensis

Question 16

What are the 4 major muscle effects that the actions of insulin have?

Answer 16

1) Increased glucose uptake
2) Promotes glycogen synthesis
3) Promotes glycolysis and carbohydrate oxidation
4) Promotes protein synthesis

Question 17

Adipocytes

Question 18

What effects do insulin have on Na+/K+ pumps?

Answer 18

Promotes K+ uptake into cells through increased activity of N+/K+ ATPase

Direct effect on hypothalamic satiety centre

Question 19

What is diabetes mellitus?

Answer 19

It’s a chronic disease that occurs when the pancreas does not produce enough insulin

Question 20

What is type 1 diabetes?

Answer 20

Where the body’s immune system destroys the pancreatic islet ( insulin- producing cells)

Question 21

What is type 2 diabetes?

Answer 21

The body doesn’t produce enough insulin because the receptors don’t respond to the insulin (resistance receptors)

Question 22

What is the result of the autoimmune destruction of the Islet, beta cells?

Answer 22

• Secrete inadequate insulin
• Hyperglycaemia
• Increased blood fatty acids
• Increased blood amino acids
• Osmotic diuresis
• Polyuria
• Hypotension
• Hyperkalaemia

Question 23

What is insulin replacement therapy?

Answer 23

It’s a treatment for diabetes that involves administering insulin to replace the insulin that the body is unable to produce on its own

Answer 24

Down regulation of insulin receptors in target tissue - insulin resistance