Exercise increases oxygen delivery demand
הוצג| English | משמעות |
|---|---|
| breathing rate/ˈbriːðɪŋ reɪt/ | קצב נשימה |
| fatigue/fəˈtiːɡ/ | עייפות |
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.
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?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Working muscles respire harder and need more oxygen and glucose, so heart rate and breathing rise to deliver them faster. The heart pumps blood but makes no oxygen, and preventing respiration would be fatal.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
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.
In the lab: 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?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- 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.
Your turn: A fictional record has 18 breaths per minute and 0.6 litres per breath. Calculate air volume per minute.
A fictional record has 18 breaths per minute and 0.6 litres per breath. Calculate air volume per minute.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 10.8 L/min. Known: 18 breaths per minute; 0.6 litres per breath. Use volume per minute = rate x volume per breath. Volume = 18 x 0.6 = 10.8 litres per minute. This is air moved, not oxygen absorbed.
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.
Not true: Air volume per minute is always equal to oxygen uptake per minute. Only part of each breath's oxygen crosses into the blood, and some air never reaches the alveoli. Air volume per minute therefore overstates oxygen uptake per minute.
- Exercise increases the energy demand of muscle cells.
- During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.
- Watch for: the heart moves blood and does not generate oxygen.
Air volume per minute is always equal to oxygen uptake per minute.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Only part of each breath's oxygen crosses into the blood, and some air never reaches the alveoli. Air volume per minute therefore overstates oxygen uptake per minute.
Number of breaths per unit time: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
breathing rate means Number of breaths per unit time.