Topic 10: Skeletal Muscle Physiology - Muscle Fatigue and EPOC

Question 1

What are the two types of muscle fatigue? (2)

Answer 1

• physiological and psychological

Question 2

What is physiological fatigue? (2)

Answer 2

• inability to maintain tension
• not completely understood

Question 3

What occurs in physiological fatigue? (2)

Answer 3

• fatigue decreases ATP use, therefore protective
• if too little, cross bridges cannot release

Question 4

What is physiological fatigue caused by? (3)

Answer 4

• depletion of energy supplies, like oxygen
• build up of end products (hydrogen and phosphate)
• failure of APs

Question 5

What occurs in build up of Hydrogen?

Answer 5

Build up of H+ from lactic acid causes muscle contraction to compress blood vessels
- decreases oxygen to muscles
- therefore anaerobic for periods, even in long term exercise

Question 6

What occurs in build up of phosphate? (5)

Answer 6

• build up from ATP -> ADP + Pi
• Pi binds to calcium
• less binds to troponin
• slows the release of the Pi from the myosin
• thus slowing down cross bridge release from actin

Question 7

What occurs during failure of APs?

Answer 7

• increased [K+] in small space of T-tubules during rapid stimuli disturbs MP and stops calcium release from SR

Question 8

What occurs if failure of AP is long term? (2)

Answer 8

• neuron runs out of ACh
• not usual in a healthy person

Question 9

What is Pyschological fatigue? (2)

Answer 9

• failure of CNS to send commands to muscles
• probably due to lactic acid

Question 10

What is EPOC? (2)

Answer 10

• excess post-exercise O2 consumption
• recovery oxygen consumption (deep rapid breathing)

Question 11

in EPOC, what is oxygen used for? (2)

Answer 11

• replenish stores of glycogen, C∼P, O2 on Hb/myoglobin
• convert lactic acid to pyruvic acid then krebs, and glucose in liver

Question 12

What occurs to body temperature in EPOC? (2)

Answer 12

• increase body temperature from exercise increases O2 demaand
• so faster chemical rxns