5.11Chapter 5: Respiration and the Respiratory System

Coping with extremes — Alhussan Biology - Stage 8 Revision Notes & Topical Questions

5 min read 7 parts Lesson 11 of 12 2 quizzes

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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

Part 1 of 5Living at high altitude

Nepal

Nepal many people live at altitudes over 4000 m.

Air

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

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.

Part 2 of 5Adaptations of people born at altitude

Adaptations of people born at altitude

Large rib cages (chests)

Large rib cages (chests) they hold larger lungs to take in more air.

More small airways and alveoli in the lungs

More small airways and alveoli in the lungs they give a larger surface area for gas exchange.

Extra capillaries in the lungs

Extra capillaries in the lungs more blood flows close to the alveoli to take up oxygen.

Many extra red blood cells

Many extra red blood cells they carry more oxygen in the blood.

Efficient

Efficient people whose families have lived at altitude for generations exchange gases very efficiently.

Part 3 of 5Acclimatisation at altitude

Sea-level people

Sea-level people they never fully adapt, but the body tries hard.

After a few weeks

After a few weeks the body makes more red blood cells with more haemoglobin, and breathing rate and heart rate increase.

Athletes

Athletes they train at altitude for a few weeks so they have more red blood cells when they compete.

Part 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.

Part 5 of 5Comparing the adaptations

Comparing the adaptations

Humans at altitude

Humans at altitude they obtain more oxygen from thin air by increasing the oxygen-carrying capacity of the blood.

Whales

Whales they use less oxygen and store more of it, because none can be taken in during a dive.

Same system

Same system in both, aerobic respiration needs a steady oxygen supply, so the organism increases supply or reduces demand.

Other examples

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.

Key terms

Term	Meaning
Altitude	Height above sea level.
Apnea	Stopping breathing.
Bradycardia	A slow heart rate.
Capillary shutdown	The closing of capillaries in some organs to save oxygen for vital ones.
Myoglobin	A protein in muscle that stores oxygen.
Haemoglobin	A protein in red blood cells that carries oxygen.