4 - Fuel Metabolism and the Control of Glucose

Question 1

What’s the difference between absorption vs postabsorptive states?

Answer 1

Absorptive: “fed state” lots of glucose

Post-absorptive: “fasting state” endogenous energy stores are mobilized to provide energy

Question 2

Explain this diagram

Answer 2

Blood glucose concentration and islet Beta cell relationship

Question 3

What causes insulin release?

Answer 3

• increased blood glucose

- neural stimulation resulting from ingestion of a meal

Question 4

What happens to glucose, insulin and glucagon when you eat?

Answer 4

After meal: glucose and insulin increase, glucagon decrease

Question 5

What is glucagon?

Answer 5

• A hormone that mobilizes molecules from storage for energy
• Secreted in response to a fall in blood glucose on pancreatic beta cells
• Opposes actions of insulin

Question 6

What’s the difference between insulin and glucagon?

Answer 6

Insulin: hormone of abundance, promotes storage of metabolic fuels

Glucagon: hormone of starvation, promotes mobilization of metabolic fuels

Question 7

Explain what’s going on here.

Question 8

What’s hypoglycaemia?

Answer 8

Low blood sugar.

occurs after rise in Insulin

Question 9

What does this table show?

Answer 9

Hormones that have effect on blood glucose levels and roles in metabolism

Question 10

What would happen if you had no access to food for an extended period of time?

Answer 10

Carbs used first
Fats used second
Proteins used second

One fat is used up, protein is used.
The loss of protein leads to muscle weakness, organ dysfunction and death.

Question 11

Which processes are anabolic and which are catabolic?

Answer 11

1. Glycogenesis: Anabolic
2. Glycogenolysis: Catabolic
3. Gluconeogenesis: Anabolic
4. Protein synthesis: Anabolic
5. Protein degradation: Catabolic
6. Fat synthesis: Anabolic
7. Fat breakdown: Catabolic

Question 12

What are the key tissues involved in metabolism?

Answer 12

1. Liver (Maintaining normal blood glucose levels - gluconeogenesis)
2. Adipose tissue (aka fat, energy storage site)
3. Muscle (amino acid storage)
4. Brain (can only use glucose as energy source)
5. Pancreas (endocrine cells - islets)

** Insulin and glucagon are most important in regulating fuel metabolism

Question 13

Is insulin anabolic or catabolic?

Answer 13

Anabolic.

Promotes cellular uptake of glucose, fatty/amino acids and promotes their conversion into glycogen, fats, proteins

Question 14

How does insulin get glucose into the cell?

Answer 14

• insulin binds to membrane protein, allows GLUT 4 transporters into the membrane
• Glucose enters through carrier mediated transport (usually facilitated diffusion)

Question 15

What are the two kinds of diabetes?

Answer 15

1. Type 1: Lack of insulin secretion

2. Type 2: Normal or increased insulin secretion but reduced sensitivity of insulin’s target cells