Muscle Fiber Type and Energy Metabolism

Question 1

Stages of Muscle Contraction

Answer 1

1. Resting state
2. Motor nerve AP arrives at motor end plate
3. ACh released, sarcolemma and membranes depolarized
4. AP transmitted via T-tubules to SR
5. Ca released from SR terminal cisternae into sarcoplasm
6. Ca bound troponin
7. Tropomyosin shift from actin binding site
8. Myosin ATPase activated and ATP hydrolyzed
9. Actin-myotsin crossbridge formation
10. Repeat. Filaments slide and sarcomere shorters

Question 2

Muscle Fiber Types

Answer 2

White: Type I, Type IIA
Red: Type IIB, Type IIX(D)

Question 3

Type I

Answer 3

1. Beta-red
2. Slow contraction
3. Oxidative metabolism
4. small diameter
5. high lipid, mitochondria, myoglobin

Question 4

Type IIA

Answer 4

1. alpha-red
2. fast contraction
3. anaerobic/aerobic

Question 5

Type IIB

Answer 5

1. alpha-white
2. fast contraction
3. anaerobic
4. larger fiber
5. high glycogen
6. low lipid, mitochondria, myoglobin

Question 6

Type IIX(D)

Answer 6

1. beta-white
2. fast contraction

Question 7

What uses ATP in the muscles?

Answer 7

`1. contractile process (most ATP used)
2. pump Ca back into SR (during relaxation)
3. maintain Na/K pump across sarcolemma

Question 8

Three processes to resynthesize ATP

Answer 8

1. Phosphocreatine
2. Glycolysis
3. Mitochondrial respiration (TCA cycle)

Question 9

Phosphocreatine is _____________ source of ATP synthesis

Answer 9

most immediate

Question 10

Aerobic metabolism is ____________ source of ATP synthesis

Answer 10

most efficient

Question 11

What happens with phosphocreatine?

Answer 11

It is broken down into H2O and creatine, ATP is made on the side

Question 12

What are the limits of phosphocreatine?

Answer 12

It is only for short, intense movements

Question 13

Chemical input and output of aerobic metabolism

Answer 13

C6H12O6 + 6O2 –> 6CO2 + 6H2O + ATP

Question 14

Key steps of aerobic metabolism

Answer 14

1. Glycolysis
2. Pyruvate processing
3. TCA Cycle
4. ETC

Question 15

How much ATP is made from 1 glycogen in aerobic metabolism?

Answer 15

37 ATP (3 from glycolysis, 2 from TCA, 32 from ETC)

Question 16

What happens during anaerobic metabolism?

Answer 16

pyruvate is converted into lactic acid (pH is lowered)

Question 17

What happens when you switch from anaerobic metabolism to aerobic metabolism?

Answer 17

1. lactic acid is transported out of the muscle and goes into the blood
2. lactic acid is converted into glucose + glycogen in the liver
3. ATP and phosphocreatine are replenished