Lecture 29

Question 2

Three main ATP sources in muscle?

Answer 2

Creatine phosphate, anaerobic glycolysis, aerobic respiration.

Question 3

Creatine phosphate system role?

Answer 3

Transfers phosphate to ADP via creatine kinase for rapid ATP; lasts ~15 s.

Question 4

When is anaerobic glycolysis used?

Answer 4

When CP stores fall (~10–15 s); provides ATP for 30–40 s, up to 2 minutes.

Question 5

Does anaerobic glycolysis require oxygen?

Answer 5

No, it is anaerobic.

Question 6

What does anaerobic glycolysis produce?

Answer 6

2 ATP per glucose and lactate.

Question 7

Aerobic respiration role?

Answer 7

Uses oxygen for ATP production; dominant for long-duration activities.

Question 8

Fuel sources for aerobic metabolism?

Answer 8

Pyruvate, fatty acids, amino acids.

Question 9

How long can aerobic metabolism sustain activity?

Answer 9

Several minutes to hours.

Question 10

Is lactate responsible for DOMS?

Answer 10

No, lactate is removed within ~30 minutes.

Question 11

Is lactate responsible for cramps?

Answer 11

No; cramps relate to injury, low blood flow, overactive neurons, or Ca2+ buildup.

Question 12

Cause of exercise acidosis?

Answer 12

ATP hydrolysis and CO2 production, not lactate.

Question 13

What happens to lactate in the liver?

Answer 13

Converted back to glucose via gluconeogenesis.

Question 14

Is lactate used by the brain?

Answer 14

Yes, it is a metabolic fuel source.

Question 15

What is lactate threshold?

Answer 15

<4 mmol/L; good indicator of performance.

Question 16

Peripheral fatigue definition?

Answer 16

Reduced ability to generate force due to muscle-level mechanisms.

Question 17

Causes of peripheral fatigue?

Answer 17

Low SR Ca2+ release, depleted CP/oxygen/nutrients, low ACh release, low pH.

Question 18

Central fatigue definition?

Answer 18

Reduced voluntary activation from spinal or supraspinal origins.

Question 19

Causes of central fatigue?

Answer 19

Protective reflexes, reduced motor drive, inhibitory feedback from fatigued muscle.

Question 20

Oxygen consumption after exercise increases because?

Answer 20

Higher body temperature, elevated heart/lung activity, tissue repair.

Question 21

Do muscles increase fibre number with training?

Answer 21

No; hypertrophy occurs, not hyperplasia.

Question 22

Endurance training adaptations?

Answer 22

Type IIx → IIa shift, ↑capillaries, ↑mitochondria, improved respiratory muscle efficiency.

Question 23

Strength training adaptations?

Answer 23

Type IIx → IIb shift, ↑capillaries/mitochondria, ↑bone density.

Question 24

Exercise-induced muscle damage signs?

Answer 24

Torn sarcolemma, disrupted Z-discs, elevated myoglobin and creatine kinase.

Question 25

Difference between spasm and cramp?

Answer 25

Spasm = painless single contraction; cramp = painful sustained contraction.

Question 26

Cause of cramps?

Answer 26

Low blood flow, overuse, injury, electrolyte imbalance.

Question 27

DOMS timeline?

Answer 27

12–48 hours post-exercise.

Question 28

Mechanism behind DOMS?

Answer 28

Microscopic muscle damage.

Question 29

Muscle regeneration mechanism?

Answer 29

Hypertrophy; satellite cells assist repair.

Question 30

Effect of aging on muscle?

Answer 30

Loss of muscle mass, replaced by connective/adipose tissue; slower reflexes.

Question 31

Neural adaptation sites?

Answer 31

Supraspinal (corticospinal/cortical circuits) and spinal (motor neurons, interneurons).

Question 32

Motor unit synchronization patterns?

Answer 32

Highest in weightlifters, intermediate untrained, lowest musicians.

Question 33

Does size principle change with training?

Answer 33

No, recruitment order is preserved.

Question 34

Role of muscle spindles?

Answer 34

Detect stretch, trigger stretch reflex to prevent injury.

Question 35

What do spindles increase during stretch?

Answer 35

Motor unit recruitment or rate coding.

Question 36

Role of Golgi tendon organs?

Answer 36

Inhibit excessive force; prevent injury from over-contraction.

Question 37

Flexion reflex function?

Answer 37

Withdraw limb from painful stimulus.

Question 38

Crossed extensor reflex function?

Answer 38

Support body weight during withdrawal.

Question 39

Cardiac muscle key features?

Answer 39

Intercalated discs, desmosomes, gap junctions, uni-nucleated.

Question 40

Why can't cardiac muscle tetanize?

Answer 40

Long refractory period prevents tetanus.

Question 41

How does cardiac muscle resist fatigue?

Answer 41

High mitochondrial content; aerobic metabolism.

Question 42

Smooth muscle features?

Answer 42

Non-striated, involuntary, spindle-shaped cells.

Question 43

Smooth muscle contraction speed?

Answer 43

Slow onset, long-lasting.

Question 44

Smooth muscle stretch ability?

Answer 44

Can stretch and still contract effectively.