Hormones of metabolism

Question 1

Insulin =

Answer 1

Insulin is released from the beta cells in the pancreas in response to elevated blood glucose levels, after a meal. It:
- promotes glucose uptake into cells
- promotes glucose conversion into glycogen i.e., glycogenesis
- inhibits glycogenolysis
- promotes glucose conversion into triglycerides- lipogenesis
- promotes protein synthesis

Question 2

Hormonal control of metabolism=

Answer 2

• Insulin is released in response to elevated blood glucose levels
• Insulin has to bind to receptor site to make cells able to uptake glucose
• Insulin promotes glucose conversion into glycogen- glycogenesis
• promotes glucose conversion to triglycerides- lipogenesis
• promotes protein synthesis

Question 3

Glucagon=

Answer 3

Released in response to decreased blood glucose levels. It:
- promotes glucose release from cells
- promotes conversion of glycogen into glucose- glycogenolysis
- promotes lipolysis
- promotes protein catabolism

Question 4

Epinephrine=

Answer 4

Released in response to stress and exercise. It:
- Increases glycogenolysis
- Increases lipolysis

Question 5

Cortisol=

Answer 5

released in response to long term stress and prolonged exercise. It:
- Increases gluconeogenesis
- increases protein catabolism
- increases lipolysis

Question 6

Thyroid hormone=

Answer 6

changes in response to exercise. It:
- Increases lipolysis and enhances β-oxidation
- Increases glycogenolysis & gluconeogenesis

Question 7

What is the overall effect of the metabolic effected hormonal control?

Answer 7

The overall effect is that it raises blood glucose levels and increases availability and use of fatty acids by tissues; glucose is therefore conserved for the brain and red blood cells.

Question 8

Dieting/ prolonged fast can cause:

Answer 8

Low insulin levels:
- With a reduced amount of insulin being secreted, there is reduced glucose uptake into cells and a greater reliance on fats for energy, so greater amounts of ketones being produced.
- There is reduced glycogenesis, as there’s a lack of glucose in the blood stream for storage, and reduced protein synthesis.
- But there is increased hepatic glucose release

Elevated levels of glucagon; cortisol
- with a lack of food being ingested, glucagon is our major circulating hormone and so it is increasing lipolysis (breaking down our fats stores to supply substrates for metabolism) but also turning to our protein stores.
- So, we get increased amino acids catabolism and gluconeogenesis, and when we start running really low on stores, we will begin to break down our body proteins to supply a substrate for energy metabolism

Question 9

Actions of the pancreas in maintaining blood glucose within a normal (homeostatic) range=

Answer 9

For an increase in blood glucose level:
1. Pancreas will release insulin which stimulates glycogen formation in the liver.
2. Release of insulin will also stimulate glucose uptake by cell sin the tissues.
3. The blood glucose then falls to normal range

For decrease in blood glucose levels:
1. Pancreas will release glucagon which stimulates glycogen breakdown in the liver.
2. Blood glucose rises to normal range