Lecture 6

Question 1

What are the main carbohydrate fuels for contracting skeletal muscles?

Answer 1

Muscle glycogen and blood glucose are the major carbohydrate fuels for contracting skeletal muscle.

Question 2

How are Muscle Glycogenolysis, muscle glucose uptake, CHO oxidation and liver glucose output influenced by exercise?

Answer 2

They are influenced by the intensity and duration of exercise.

Question 3

How is muscle glycogenolysis maintained?

Answer 3

Muscle glycogenolysis is regulated by local and hormonal factors

Question 4

How is the regulation of the liver output of glucose?

Answer 4

Liver glucose output is regulated by redundant controls; this ensures that optimal function is maintained.

Question 5

What does training make the body consume for energy?

Answer 5

Training reduces reliance of the body on carbohydrates and instead directs metabolism to rely on fatty acid oxidation

Question 6

How is glycogen broked down?

Answer 6

glycogen phosphorylase breaks down glycogen

Question 7

What happens to lactate after it is produced?

Answer 7

lactate leaves the muscle but it can be taken up and converted to pyruvate and oxidised

Question 8

What happens to glucose when it is phosphorylated?

Answer 8

Hexokinase phosphorylates glucose which is irreversible meaning the glucose is destined to be metabolised as soon as it’s phosphorylated by hexokinase.

Question 9

How does an increase in exercise intensity influence muscle glycogen breakdown?

Answer 9

With increase in exercise intensity an increase in glycogen breakdown follows. At high intensity this glycogen is broken down to lactate

Question 10

How is glycogen breakdown influenced by duration of exercise?

Answer 10

glycogen breakdown decreases with duration of exercise

Question 11

What are the main factors regulating glycogenolysis?

Answer 11

Ca2+ (calcium activates glycogen phosphorlyase) and Pi (lots of ATP breakdown means more breakdown desired)
Adrenaline (High levels mean high intensity exercis)

Question 12

What are other factors regulating glycogenolysis?

Answer 12

More glycogen in the muscle increases glycogen breakdown.
Free Fatty Acid reduction can increase glycogenolysis and vice versa
High temperature increases adrenaline meaning more glycogen is broken down.

Question 13

What does training do to glycogen breakdown and anaerobic respiration?

Answer 13

Training reduces glycogen breakdown at a given intensity. It also reduces anaerobic respiration.

Question 14

What factors effect glucose uptake?

ITS AFFECT YOU DAFT CUNT

Answer 14

Glucose uptake increases with an increase in intensity and with duration.

Question 15

How is glucose uptake regulated?

Answer 15

Glucose uptake is limited by rate of diffusion which is affected by:
Blood glucose concentration
Amount of receptors
Blood flow
Metabolic rate

Question 16

How do glycogen levels affect glucose uptake?

Answer 16

More glycogen = Less glucose uptake

Question 17

Is insulin necessary for glucose uptake during exercise?

Answer 17

NO

Question 18

What is the effect of adrenaline on glucose uptake?

Answer 18

No known effect of adrenaline on glucose uptake

Question 19

How are liver glucose output and glucose uptake by muscles related?

Answer 19

Liver glucose output is closely matched with glucose uptake this is to maintain stable levels of glucose in the blood. This effect falls with duration.

Question 20

Does gluconeogenesis occur in exercising muscles?

Answer 20

During exercise gluconeogenesis only happens in the liver.

** needs verifying **

Question 21

Interesting Fact

Answer 21

1 hour of exercise drops glycogen by about 50%

Question 22

What happens to liver gluconeogenesis during exercise?

Answer 22

When liver is low on glycogen it increases gluconeogenesis.

Question 23

What substrates can be used for gluconeogenesis?

Answer 23

Amino acids, glycerol, pyruvate, and lactate can be used to produce more glycogen by gluconeogenesis

Question 24

What factors are involved in the regulation of liver glucose output during exercise?

Answer 24

Feedforward and feedback mechanisms (liver output increases in anticipation of exercise)
Insulin & glucagon
sympathetic nerves
Liver glycogen (more glycogen = more release of glycogen into the blood)
Blood glucose (if glucose enters the body via gut then liver doesn’t need to release glucose either)

Question 25

How does training affect glucose uptake, oxidation and gluconeogenesis?

Answer 25

After becoming trained there is a reduction in glucose uptake at a given exercise intensity. A reduction in glucose oxidation follows. Gluconeogenesis is also reduced.

Question 26

What happens to PDH activity with increased intensity and duration of exercise?

Answer 26

Increase in exercise intensity there is an increase in PDH activation. With duration PDH activity decreases due to lower dependence on carbohydrate metabolism.