Question

match the following.

sarcomere lengthens as calcium is returned to sarcoplasmic reticulum, and the troponin-tropomyosin complex attaches to myosin binding sites on actin.

aerobically break down fatty acids and glucose

anaerobically utilize creatine phosphate for energy

time between the stimulation of a muscle and the beginning of a muscle contraction

contain gap junctions that permit rapid electrical stimulation of muscle cells

actin filaments slide over myosin filaments, and the sarcomere shortens

increases muscle force by activating more motor units

relaxation
latent period
fast-twitch fibers
fatigue
intercalated discs
twitch
contraction
slow-twitch fibers

Explanation:

1. Muscle relaxation involves calcium being pumped back into the sarcoplasmic reticulum, which restores the troponin-tropomyosin complex to block myosin binding sites on actin, lengthening the sarcomere.
2. Slow-twitch muscle fibers rely on aerobic metabolism to break down fatty acids and glucose for sustained, low-intensity contractions.
3. Fast-twitch muscle fibers use anaerobic energy sources like creatine phosphate for quick, high-intensity bursts of energy.
4. The latent period is the short delay between a muscle being stimulated and the start of contraction, as the signal propagates and calcium is released.
5. Intercalated discs are specialized structures in cardiac muscle that contain gap junctions, allowing rapid electrical communication between muscle cells.
6. Muscle contraction follows the sliding filament theory, where actin filaments slide over myosin filaments, causing the sarcomere to shorten.
7. Motor unit recruitment is the process of activating more motor units to increase the overall force of a muscle contraction.

Answer:

• Sarcomere lengthens as calcium is returned to sarcoplasmic reticulum, and the troponin-tropomyosin complex attaches to myosin binding sites on actin. → relaxation
• aerobically break down fatty acids and glucose → slow-twitch fibers
• anaerobically utilize creatine phosphate for energy → fast-twitch fibers
• Time between the stimulation of a muscle and the beginning of a muscle contraction → latent period
• contain gap junctions that permit rapid electrical stimulation of muscle cells → intercalated discs
• Actin filaments slide over myosin filaments, and the sarcomere shortens → Contraction
• increases muscle force by activating more motor units → motor unit recruitment (implied correct match)