Exercise increases oxygen delivery demand
| English | 中文 | Pinyin |
|---|---|---|
| breathing rate/ˈbriːðɪŋ reɪt/ | 呼吸频率 | hū xī pín lǜ |
| fatigue/fəˈtiːɡ/ | 疲劳 | pí láo |
What would explain this observation?
- During activity, working muscles need more energy. The body increases delivery of oxygenated blood, rather than producing oxygen in the heart.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Exercise increases the energy demand of muscle cells. Heart rate, breathing rate 呼吸频率 and breath volume increase, helping supply muscles with more oxygenated blood for aerobic respiration. If oxygen supply is insufficient for the demand, anaerobic respiration takes place in muscles. Incomplete oxidation of glucose causes lactic acid to build up and creates an oxygen debt.
- breathing rate: Number of breaths per unit time; fatigue 疲劳: Reduced ability of muscles to contract efficiently during prolonged vigorous activity.
Why do heart rate and breathing increase during exercise?
During long periods of vigorous activity muscles become fatigued and stop contracting efficiently. Breathing can remain elevated during recovery as extra oxygen is needed. Distinguish rate from volume: breaths per minute and volume per breath are separate quantities, so both can affect the volume of air moved per minute.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- During long periods of vigorous activity muscles become fatigued and stop contracting efficiently. Breathing can remain elevated during recovery as extra oxygen is needed. Distinguish rate from volume: breaths per minute and volume per breath are separate quantities, so both can affect the volume of air moved per minute.
- Use supplied fictional exercise-and-recovery records or a voluntary teacher-approved low-intensity observation. Participation needs consent and an alternative data task; do not test maximal effort, illness, medication or distress. Keep timing and measurement method consistent and protect personal information. Explain trends without treating classroom results as a health diagnosis.
Which two habits make the investigation or model in this case more defensible?
Use supplied fictional exercise-and-recovery records or a voluntary teacher-approved low-intensity observation. Participation needs consent and an alternative data task; do not test maximal effort, illness, medication or distress. Keep timing and measurement method consistent and protect personal information. Explain trends without treating classroom results as a health diagnosis.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a fictional record has 12 breaths per minute and 0.5 litres per breath at rest, giving 6 litres per minute. During the stated activity, 20 breaths per minute and 0.8 litres per breath give 16 litres per minute. This is air movement, not pure oxygen uptake; air contains other gases and exchange is not complete.
A fictional record has 18 breaths per minute and 0.6 litres per breath. Calculate air volume per minute. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A fictional record has 18 breaths per minute and 0.6 litres per breath. Calculate air volume per minute.
The result is 10.8 L/min. Known: a fictional record has 12 breaths per minute and 0.5 litres per breath at rest, giving 6 litres per minute. During the stated activity, 20 breaths per minute and 0.8 litres per breath give 16 litres per minute. This is air movement, not pure oxygen uptake; air contains other gases and exchange is not complete.
Check the conclusion and its limits
- The heart moves blood and does not generate oxygen. Faster breathing does not mean every oxygen molecule in the air enters the blood. The detailed liver handling of lactic acid and quantitative definition of oxygen debt are Higher Tier content taught separately.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Air volume per minute is always equal to oxygen uptake per minute. This claim is false: The heart moves blood and does not generate oxygen. Faster breathing does not mean every oxygen molecule in the air enters the blood. The detailed liver handling of lactic acid and quantitative definition of oxygen debt are Higher Tier content taught separately.
Exercise increases oxygen delivery demand: During long periods of vigorous activity muscles become fatigued and stop contracting efficiently. Breathing can remain elevated during recovery as extra oxygen is needed. Distinguish rate from volume: breaths per minute and volume per breath are separate quantities, so both can affect the volume of air moved per minute.
Air volume per minute is always equal to oxygen uptake per minute.
The heart moves blood and does not generate oxygen. Faster breathing does not mean every oxygen molecule in the air enters the blood. The detailed liver handling of lactic acid and quantitative definition of oxygen debt are Higher Tier content taught separately.
Number of breaths per unit time: write the technical term.
breathing rate means Number of breaths per unit time.