Answer Happy

Follow-up Question 3: Compare your breath-hold times for Trial 4 (maximal inhalation following re-breathing) and Trial 2 (maximal inhalation). Typically, a person can hold their breath longer during Trial 2. (Note: Your results may have been different). What is the best explanation for why most people are normally able to hold their breaths longer during Trial 2 versus Trial 4? The lung volume is larger during Trial 2, which allows more oxygen to be stored in the lungs during the breath- hold. O The production of CO2 from the body's tissues was lower in Trial 2, allowing more time to elapse before arterial PCO2 built up to the critical level triggering people to breathe. O During Trial 4, the levels of arterial PCO2 were higher before the start of the breath-hold when compared to Trial 2. This caused less time to elapse before arterial PCO2 built up to the critical level triggering people to breathe. O During Trial 4, there was extra oxygen in the bag, allowing a larger supply of oxygen during the breath-hold. This allowed people to hold their breaths for a shorter amount of time during Trial 2, since they ran out of oxygen faster.