7.4 and 7.5 Accumulation of by-products

What causes the decrease in muscle pH during high-intensity exercise?

• Accumulation of hydrogen ions (H+)
• Accumulation of lactate
• Depletion of oxygen
• Increase in bicarbonate
• Rise in calcium ions

Answer explanation

H+ ions increase acidity, lowering muscle pH during anaerobic glycolysis.

How does a lower muscle pH affect energy production?

• It inhibits glycolytic enzymes
• It increases CP resynthesis
• It accelerates ATP production
• It improves calcium binding
• It promotes oxygen delivery

Answer explanation

A lower pH slows glycolysis by inhibiting enzymes involved in the process.

Which of the following is a by-product of ATP breakdown that contributes to fatigue?

• Inorganic phosphate (Pi)
• Oxygen
• Glucose
• Carbon dioxide
• Creatine

Answer explanation

Pi builds up from CP and ATP breakdown and is linked to fatigue.

What is a known impact of Pi and ADP accumulation during exercise?

• Interference with muscle contraction
• Improved ATP binding
• Enhanced calcium release
• Increased glycogen breakdown
• Faster muscle recovery

Answer explanation

Pi and ADP are thought to interfere with calcium and cross-bridge cycling, reducing contraction force.

What is the primary cause of fatigue in the anaerobic glycolysis system?

• Hydrogen ion accumulation
• Oxygen depletion
• Glycogen sparing
• Dehydration
• Bicarbonate loss

Answer explanation

The buildup of H+ is the main contributor to fatigue when this system is dominant.

Which statement about lactate is supported by current research?

• Lactate does not directly cause fatigue
• Lactate blocks calcium release
• Lactate prevents ATP resynthesis
• Lactate damages muscle tissue
• Lactate increases muscle pH

Answer explanation

Lactate is no longer considered a fatigue factor; it may help buffer H+ ions.

How does the accumulation of ADP during intense activity affect muscle performance?

• It contributes to muscular fatigue
• It enhances ATP resynthesis
• It improves enzyme function
• It buffers muscle acidity
• It stimulates glucose uptake

Answer explanation

ADP buildup is associated with fatigue, possibly by interfering with force generation.

What happens to muscle pH as H+ ions accumulate?

• It decreases, causing acidosis
• It increases, causing alkalosis
• It remains neutral
• It rapidly fluctuates
• It stays slightly basic

Answer explanation

H+ accumulation lowers pH, increasing acidity and contributing to fatigue.

How does inorganic phosphate (Pi) accumulation impair muscle function?

• Interferes with calcium’s role in contractions
• Enhances actin-myosin binding
• Increases enzyme activity
• Stimulates CP resynthesis
• Raises pH of muscle cells

Answer explanation

Pi may interfere with calcium and the contractile process, weakening muscle contractions.

What is the primary cause of decreased force and velocity of muscle contractions during anaerobic glycolysis?

• Inhibition of glycolytic enzymes by H+
• Excess lactate production
• Fuel depletion
• Bicarbonate loss
• Reduced oxygen uptake

Answer explanation

H+ accumulation lowers pH, inhibiting glycolytic enzymes and reducing contraction efficiency.