U3 Lecture 22

Question 1

What is the immediate source of energy to create tension?

Answer 1

ATP

Question 2

What are the two ways ATP is hydrolyzed?

Answer 2

1. hydrolysis by the myosin head group fuels tension generation
2. hydrolysis by the Ca2+ pump of the SR supports relaxation

Question 3

What are the two energy metabolism in the cell?

Answer 3

Anaerobic and Aerobic

Question 4

What is anaerobic

Answer 4

Glycolysis only (breakdown of glucose)

Question 5

What is aerobic?

Answer 5

glycolysis and oxidative phosphorylation (has O2)

Question 6

Where does ATP come from?

Answer 6

1. Cell pool of ATP
2. Creatine Phosphate (CP) pool
3. Anaerobic Glycolysis (glucose breakdown)
4. Aerobic metabolism - glucose,(from glycogen) fatty acids (from lipids) and amino acids (from proteins)

Question 7

Cell pool of ATP

Answer 7

ATP is not “stored” bc there’s only enough to support ~2 seconds of maximal force

Question 8

Creatine Phosphate (CP) pool

Answer 8

CP stores ‘high energy phosphate’ = ~ 15 seconds of maximal contraction

Question 9

ATP formula for after a meal

Answer 9

ATP + C -> ADP + CP

Question 10

ATP formula during exercise

Answer 10

ADP + CP -> ATP + C

Question 11

Define creatine

Answer 11

a small amino acid like molecule that is synthesized in the liver, kidney, and pancreas and transported to muscle fibers

Question 12

What do muscle cells “store” ATP as?

Answer 12

creatine phosphate

• in a relaxed muscle fiber, there is 3-6x more creatine phosphate than ATP

Question 13

Glycogen used anaerobically

Answer 13

• occurs in the ctyoplasm
• occurs rapidly
• can support ~2 min of contraction

Question 14

Glycogen fat and protein used aerobically

Answer 14

• occurs in mitochondria and is SLOW

- can support ~40 min to several hours of contraction (intensity dependent)

Question 15

Energy Use in Sustained Activity

Answer 15

1. Resting - aerobic production of ATP - supports activity and buildup of CP pool
2. Moderate - aerobic production of ATP increases - supports activity, but NO CP buildup
3. Peak - aerobic production of ATP is maximal; as O2 becomes limiting, anaerobic metabolism fills needs - CP depleted - lactic acid builds up Increase [H+]

Question 16

Pathway of fatigue

Answer 16

psychological -> nervous system -> muscle

Question 17

What is the major cause of fatigue?

Answer 17

Failure of EC coupling because of increase [Pi]cell

1. due to breakdown of Creatine Phosphate
2. Inhibits Ca2+ release from SR

Question 18

Other causes of fatigue

Answer 18

insufficient Oxygen, depletion of glycogen, ADP and lactate build up

Question 19

Define the Cori Cycle

Answer 19

Lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is metabolized back to lactate

Question 20

Define lactic acid

Answer 20

Byproduct of intense exercise that causes muscle fatigue and soreness

Question 21

What also eliminates lactate?

Answer 21

Aerobic cellular respiration in the heart, kidneys and skeletal muscle

Question 22

Define O2 Debt

Answer 22

Excess Post-exercise oxygen comsumption

• the cost of ‘resting’ the system after exercise

Question 23

How does the body reset itself after exercise?

Answer 23

1. Metabolizing lactic acid

2. Repair of tissue

Question 24

Elevated O2 consumption after exercise

Answer 24

1. Lactic acid conversion back to glycogen in the liver (cori cycle)
2. Resynthesize creatine phosphate
3. Replace oxygen removed from myoglobin
4. Repair