Respirometers and Anaerobic Respiration

Respirometers and Anaerobic Respiration


Function and Components

  • A respirometer is a device used to measure the rate of carbon dioxide production in respiration, as an indicator of metabolic rate.
  • It consists of a chamber that contains the organism or tissue, a manometer to measure pressure changes, and an absorber of carbon dioxide.
  • As organisms respire, they use up oxygen and produce carbon dioxide. The carbon dioxide is absorbed, causing a fall in pressure which moves the liquid in the manometer.

Interpretation of Results

  • A change in the level of the manometer fluid indicates a change in the volume of gas in the respirometer, which implies metabolic activity.
  • Increase in fluid level indicates a decrease in gas volume, suggesting respiration has occurred, while decrease signifies gas production.
  • It is important to control environmental conditions (like temperature), since these can affect respiration rate and thus the accuracy of measurements.

Anaerobic Respiration


  • Anaerobic respiration is respiration without oxygen, producing energy from the anaerobic breakdown of glucose.
  • Two common types exist in humans: lactic acid and alcohol fermentation.
  • In muscle cells, glucose is converted into lactic acid, while yeast and some bacteria convert glucose to ethanol and carbon dioxide.

Yield and Efficiency

  • Anaerobic respiration produces just 2 ATP per glucose molecule, a much lower energy yield compared with aerobic respiration’s 38 ATP.
  • However, it has the advantage of being able to occur even when oxygen supplies are low or non-existent.
  • Despite the lower energy yield, anaerobic respiration is an essential survival mechanism during times of oxygen deficiency.

Role in Muscles

  • During intense exercise, when oxygen can’t be delivered to muscles fast enough for aerobic respiration, muscles resort to anaerobic respiration.
  • Under these conditions, lactic acid builds up in the muscles and blood, potentially leading to muscle fatigue and a burning sensation.
  • After exercise, the body needs to remove the lactic acid from muscles and convert it back to glucose. This requires oxygen and leads to oxygen debt.