M3 - Converting Energy Flashcards
What is a sarcomere?
The contractile unit of a muscle cell.
What filaments are found in a sarcomere?
Actin (thin) and myosin (thick).
What ion is required for actin and myosin to bind?
Calcium.
What molecule is needed for actin and myosin to detach?
ATP.
What are the three mechanisms muscle cells use to produce ATP?
Creatine phosphate, fermentation, and aerobic cellular respiration.
How does creatine phosphate help regenerate ATP?
It donates a phosphate group to ADP during contraction.
Can creatine phosphate directly power muscle contraction?
No, it only regenerates ATP.
What is creatine phosphate made from?
The amino acid creatine, which is phosphorylated and stored in muscles.
What type of athletes may benefit from creatine phosphate?
Sprinters and weightlifters—those needing short, intense bursts of energy.
What happens during aerobic cellular respiration?
Glucose or fatty acids are converted to ATP in the presence of oxygen.
What pigment helps muscles store oxygen?
Myoglobin, which has a higher affinity for oxygen than hemoglobin.
What causes an oxygen deficit in muscles?
When oxygen is insufficient for aerobic respiration and fermentation occurs instead.
What is produced during fermentation in muscle cells?
Lactic acid.
What happens if lactic acid builds up?
Sarcoplasm becomes acidic, enzymes stop functioning, causing cramping and fatigue.
How can lactate be reused?
It can be converted back to pyruvate or sent to the liver to make glycogen.
Why is glucose more essential to the brain than to muscles?
The brain can only use glucose, while muscles can use fatty acids too.
How does athletic training affect mitochondria?
Increases mitochondria, enabling muscles to use fatty acids and save glucose for the brain.
What are slow-twitch muscle fibers?
Type I fibers; dark, high in myoglobin, many capillaries, resist fatigue, suited for endurance.
What are fast-twitch muscle fibers?
Type II fibers; light, low in myoglobin, fatigue quickly, suited for power and speed.
What are intermediate muscle fibers?
Fast-twitch fibers with high oxidative capacity, fatigue slowly, increased by training/genetics.
What is a myogram?
A graph showing the force of muscle contraction over time.
What are the phases of a single muscle twitch?
Latent period, contraction period, and relaxation period.
What is summation in muscle contraction?
When stimuli occur before full relaxation, resulting in stronger contractions.
What is tetanus (in muscle physiology)?
A sustained contraction from rapid, repeated stimulation with no relaxation phase.
