Endocrine pancrease - Glucagon

Question 1

What is glucagon produced by and what type of hormone is it?

Answer 1

It is a peptide hormone produced by Pancreatic A cells in islets of langerhans

Question 2

What is the function of glucagon?

Answer 2

Its purpose is to raise blood sugar a

• Mainly acts upon the liver
• Plasma half life 5-10 mins

Question 3

Describe the glucose counter regulatory hormones?

Answer 3

• Glucagon
• Cortisol
• GH
• Epinephrine

Question 4

What receptors do glucagon bind too?

Answer 4

G-protein coupled receptors linked too adenylate cyclase/cAMP

Question 5

What are the primary functions of glucagon?

Answer 5

• Increase Liver glycogenolysis
• Increase gluconeogensis (Substrates aa and glycerol)
• Formation of ketones from fatty acids (lipolysis)
  These processes occur in the liver
• Also Adipose breaks down tricylglycerol to fatty acids and glycerol
• Muscles break down proteins to amino acids

Question 6

Describe amino acids and its effect on insulin and glucagon production

Answer 6

• A meal high in amino acids causes the release of insulin and glucagon
• If it weren’t for the counteract effects of glucagon the insulin stimulating effects would result in very low amino acids

Question 7

What are the stimuli that promote glucagon production

Answer 7

• Low [BG}
• High amino acids, prevents hypoglycemia following insulin release
• Sympathetic innervation and epinephrine, B2
• Cortisol
• Stress, exercise & infection

Question 8

Stimuli that prevent glucagon release

Answer 8

• Glucose
• FFA and ketones
• Insulin
• Somatostatin

Question 9

Describe parasympathetic (vagus) activity on Islet cells

Answer 9

• Increases stimulation of insulin

- Glucagon to an extent to prevent hypoglycemia

Question 10

Describe the effects of Sympathetic activation

Answer 10

• Increased glucagon production

- Increased epinephrine and inhibition of insulin

Question 11

Describe the effects of glucagon

Answer 11

• Liver Glycogenolysis

- Gluconeogensis

Question 12

Describe the effects of epinephrine

Answer 12

• Increased muscle glycogenolysis
• Increased Liver glycogenolysis
• Increased gluconeogensis
• Increased lipolysis

Question 13

Describe the effects of cortisol

Answer 13

• Increased gluconeogensis
• Inhibition of glucose uptake
• Lipolysis
• Protein catabolism

Question 14

Describe the effects of growth hormone

Answer 14

• Gluconeogensis
• Inhibition of glucose uptake
• Lipolyisis

Question 15

Describe the release and function of somatostatin

Answer 15

Somatostatin is released from the D cells of the pancrease (and hypothalmus via GHIH)

• Main function is too slow down gastric motility
• Strongly suppresses the release of insulin and glucagon

Question 16

Describe the effects of exercise on [BG}

Answer 16

• The entry of glucose into the skeletal muscle is increased during exercise even in absence of Insulin

Question 17

Describe the mechanism of exercise on the GLUT 4 transporters

Answer 17

• Increases the insulin sensitivity of muscle and causes an increase in the number of GLUT 4 transporters in the membrane

Question 18

Describe the production of ketone bodies

Answer 18

During periods of starvation, FFA are broken down from adipose tissue
- The liver will convert excess FFA into ketone bodies

Question 19

Describe the brains adaption during periods of starvation

Answer 19

• The brain adapts to use ketones in periods of starvation

Question 20

Describe the last fat store to be depleted in starvation

Answer 20

Protein stores in muscle are the last to be depleted

- Fat stores depleted first because breakdown of protein leaves you venerable to muscle wasting and infection