BIOLOGY · Stage 8 · Chapter 5: Respiration and the Respiratory System
Biology 5.11 Coping with extremes — High Altitude and Marine Adaptations
5 min read 5 parts Lesson 11 of 12
Lesson summary
Biology 5.11 Coping with extremes — High Altitude and Marine Adaptations — Alhussan International Academy — Biology (Stages 7–9) notes: Explain how humans at high altitude and diving whales are adapted to a low oxygen supply.Nepal — many people live at altitudes over 4000 m.Air —…
- Effect on people born at sea level
- Large rib cages (chests)
- More small airways and alveoli in the lungs
- Extra capillaries in the lungs
- Many extra red blood cells
- Sea-level people
Section 1 of 5Living at high altitude
- Nepal
- many people live at altitudes over 4000 m.
- Air
- it still contains about 21% oxygen, but the air pressure is much lower than at sea level.
- The pressure gradient between the air and the lungs when breathing in is smaller.
- Less air moves into the alveoli, so less oxygen is available to be exchanged with every breath.
- Effect on people born at sea level
- they find it hard to get enough oxygen, and blood oxygen saturation falls as altitude rises, so many feel tired and unwell above 4000 m.
Section 2 of 5Adaptations of people born at altitude
- Large rib cages (chests)
- they hold larger lungs to take in more air.
- More small airways and alveoli in the lungs
- they give a larger surface area for gas exchange.
- Extra capillaries in the lungs
- more blood flows close to the alveoli to take up oxygen.
- Many extra red blood cells
- they carry more oxygen in the blood.
- Efficient
- people whose families have lived at altitude for generations exchange gases very efficiently.
Section 3 of 5Acclimatisation at altitude
- Sea-level people
- they never fully adapt, but the body tries hard.
- After a few weeks
- the body makes more red blood cells with more haemoglobin, and breathing rate and heart rate increase.
- Athletes
- they train at altitude for a few weeks so they have more red blood cells when they compete.
Section 4 of 5Whales and long dives
- Whales
- they are mammals, so they get their oxygen from the air.
- Humpback whales dive to around 200 m for up to 30 minutes, then surface, take several enormous breaths and dive again.
| Adaptation | What it does |
|---|---|
| Apnea | The whale stops breathing while under water, because breathing in water would drown it |
| Bradycardia | The heart rate slows to only a few beats per minute, reducing the oxygen used by tissues |
| Capillary shutdown | Capillaries in areas such as the digestive system close during a dive, saving blood and oxygen for organs that need it |
| Large myoglobin stores in the muscles | Myoglobin, similar to haemoglobin, takes oxygen from the blood and stores it in muscles so they respire aerobically for most of the dive |
- End of a dive
- when the oxygen store is empty the muscles respire anaerobically and lactic acid builds up, eventually ending the dive.
Section 5 of 5Comparing the adaptations
- Humans at altitude
- they obtain more oxygen from thin air by increasing the oxygen-carrying capacity of the blood.
- Whales
- they use less oxygen and store more of it, because none can be taken in during a dive.
- Same system
- in both, aerobic respiration needs a steady oxygen supply, so the organism increases supply or reduces demand.
- Other examples
- llamas and vicuñas in the Andes have haemoglobin that binds oxygen more tightly, and seals divert blood to the brain, heart and lungs during dives.
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