Brenda - Tissue Specific Metabolism

Question 1

What is the preferred metabolism by the muscle?

Answer 1

Glucose
Fatty acids
Ketone bodies

Question 2

What is the preferred metabolism by the heart?

Answer 2

Fatty acids

Question 3

What is the preferred metabolism by the brain

Answer 3

Glucose nearly entirely except in starvation

Question 4

How does ATP help muscle contraction?
(3)

Answer 4

Myosin in muscle has an enzyme ATPase which breaks down ATP to ADP

This releases energy -> causes myosin to crossbridge and attach and pull on actin

After one pull another ATP attaches on for the myosin to attach to the next actin

Question 5

What is slow twitch muscle also called?

Answer 5

Red muscle

Question 6

What is slow twitch muscle?
(4)

Answer 6

Muscle that provides relatively low tension and is highly resistant to fatigue

Produces ATP by oxidative phosphorylation

Very rich in mitochondria

Dense network of blood vessels to bring oxygen needed for ATP production

Question 7

What is fast twitch muscle also called?

Answer 7

White muscle

Question 8

What is fast twitch muscle?
(5)

Answer 8

Muscle that is quicker to fail as it uses ATP faster than it can replace it when active

Fewer mitochondria than red muscle

Less well supplied with blood vessels

Can develop greater tension

With training the endurance of fast twitch can be improved

Question 9

How much of body glycogen stored in muscle?

Answer 9

3/4

Question 10

Describe metabolism in muscle
(3)

Answer 10

Primary fuel = fatty acids from adipose tissue and ketone bodies from liver

These are oxidised and degraded to yield acetyl CoA, which enters TCA for oxidation to CO2

Ensuring transfer of electrons to O2 provides energy for ATP synthesis by oxidative phosphorylation

Question 11

Describe metabolism in fast-twitch muscle
(4)

Answer 11

High demand for ATP

Aerobic respiration alone insufficient for ATP supply

Glycogen and glucose broken down to lactate

Adrenaline stimulates glycogen breakdown (liver and muscle)

Question 12

Describe muscle after exercising
(3)

Answer 12

Heavy breathing -> most of O2 used for oxidative phosphorylation in liver

The ATP produced is used for gluconeogenesis in the liver from lactate

The glucose formed then returns to muscles and is converted to glycogen via the Cori cycle

Question 13

Describe metabolism used for a burst of heavy activity
(4)

Answer 13

Skeletal muscle contains phosphocreatine

Energy for contraction comes from molecules of ATP (this is in limited supply)

Creatine phosphate stores excess energy released by the mitochondria

Creatine phosphate is present to regenerate ATP from ADP and phosphate

Phosphocreatine + ADP in the presence of creatine kinase forms ATP and creatine