1. Muscle Tissue Cont. Muscle Metabolism Chapter 10

2. Skeletal Muscle Metabolism 3 ways to replenish ATP: 1.Creatine phosphate energy storage system 2.Aerobic respiration 3.Anaerobic respiration = lactic acid system

3. 1. Creatine Phosphate (CP) CP = high energy compound which can be used to make ATP Duration of energy: 15 seconds; only small amount available CP + ADP ↔ creatine + ATP

4. 2. Aerobic Respiration Uses oxygen for ATP production Uses many substrates: carbohydrates, lipids, proteins Good for long term exercise Duration of energy: hours

5. 3. Anaerobic Respiration When O 2 is unavailable Very inefficient, does not create much ATP Produces lactic acid as a by-product – ouch! Duration of energy: 30 – 60 seconds

6. Summary of Muscle Metabolism

7. Regular small contractions caused by spinal reflexes These contractions do not produce movement Provide constant tension development – muscles are firm Example: neck, back and leg muscles – maintain posture Muscle Tone poor muscle tone

8. Other Muscle Terminology Muscle fatigue = muscle can no longer contract despite neural stimulation Muscle hypertrophy = enlargement of muscle due to repeated stimulation; muscle fibers develop more mitochondria, more enzymes for aerobic respiration, more glycogen reserves & grow in size Muscle atrophy = loss of muscle tone & mass due to lack of stimulation

9. Types of Muscle Fibers Fast fibers = white muscles; most skeletal fibers; can contract in 0.01 sec or less after stimulation Slow fibers = red muscles; take three times as long to contract after stimulation; contain lots of myoglobin Intermediate fibers It is genetically determined which types of fiber you have (exercise can change it somewhat)