High Elevation (W12c)

Question 1

Air composition? (3)

Answer 1

• 78% N2.
• 21% O2.
• 0.04% CO2.

Question 2

What is the problem with high elevation?

Answer 2

The partial pressure of O2 is low at high elevation.

Question 3

Partial pressure?

Answer 3

= pressure exerted by a single gas.

Question 4

Dalton’s law?

Answer 4

= states that the total pressure exerted is equal to the sum of the partial pressures of the individual gases, provided that volume & temperature are constant.

Question 5

Atmospheric pressure?

Answer 5

= the force exerted on a surface by the air above it as gravity pulls it to Earth.

Question 6

Atmospheric pressure at sea level value?

Answer 6

760 mmHg.

Question 7

How to determine the partial pressure of gases (N2, O2 & CO2) given atmospheric pressure at sea level?

Answer 7

● PN2
= 760 × 0.78 = 593mmHg.

● PO2
= 760 × 0.21 = 160mmHg.

● PCO2
= 760 × 0.0004 = 0.3mmHg.

Question 8

What happens as you go to higher altitudes?

Answer 8

Low Partial pressure of O2, Low diffusion gradient.

Question 9

What will be the consequence of inspiring air with a low partial pressure of O2?

Answer 9

Because mammals have tidal ventilation, the inspired air is mixed with “stale” air that is left inside the alveoli at the end of normal expiration, which will further drop the partial pressure of O2 in the lungs.

Question 10

What determines how much O2 can be extracted from the air & delivered to the tissues that require O2 for cellular respiration?

Answer 10

The partial pressure gradient between O2 in the alveoli & the capillaries.

Question 11

Explain “Effect of elevation on PO2” graph?

Answer 11

• Compares the partial pressures of O2 throughout the system of a person living at sea level & a person living at 4540m above sea level (highest elevation which humans inhabit).

• Person living at high elevation has small partial pressure gradients between air in the alveoli & venous blood.

Question 12

Acclimatization?

Answer 12

= the process in which an individual organism adjusts to a change in its environment.

Question 13

Acclimatization types? (2)

Answer 13

• Short-term acclimatization.
• Long-term acclimatization.

Question 14

Physiological acclimatizations at high altitude? (6)

Answer 14

• Body becomes more efficient at taking deep breaths.
• Increased production of red blood cells (more hematocrit).
• Pressure in pulmonary arteries increases for efficient lungs.
• More kidney synthesis of erythropoietin.
• Increased capillary density.
• Increased Myoglobin.

Question 15

Short-term acclimatization period?

Answer 15

4-7 days.

Question 16

Medium-term acclimatization period?

Answer 16

~ 3 months.

Question 17

First climbers to reach the peak of Mount Everest in 1953? (2)

Answer 17

• Hillary.
• Norgay.

Question 18

High-altitude physiologist who developed the clothing & equipment?

Answer 18

Griffith Pugh.

Question 19

Mountaineers who summited Mount Everest without supplementary O2? (2)

Answer 19

• Messner.
• Habeler.

Question 20

Challenges of summiting Mt Everest? (3)

Answer 20

• Increased ventilation.
• Headaches.
• Can never get warm due to lack of O2 to generate heat.

Question 21

Long-term acclimatization to high altitude?

Answer 21

Via genetic adaptation.

Question 22

Egs of the Native populations that have evolved genetic adaptations to cope with hypoxia? (3)

Answer 22

• Tibetans.
• Andeans.
• Ethiopian highlanders.

Question 23

Genetic adaptations in Tibetans? (5)

Answer 23

• Decreased Hb concentrations (rbc).
• Low arterial O2 saturation.
• More vasodilation.
• High breathing rate.
• Large lung volume.

Question 24

Genetic adaptations in Andeans? (2)

Answer 24

• Increased Hb concentrations (rbc).
• High arterial O2 saturation.

Question 25

Genetic adaptations in Ethiopian highlanders? (2)

Answer 25

• Same Hb concentrations.
• Same arterial O2 saturation.

• Same as people living at sea level (no tweaks in their genes).

Question 26

CMS stands for?

Answer 26

Chronic Mountain Sickness.

Question 27

Incidence of CMS in Tibetans?

Answer 27

1%.

Question 28

Incidence of CMS in Andeans?

Answer 28

18%.

Question 29

Incidence of CMS in Ethiopian highlanders?

Answer 29

0%

Question 30

Hypoxia?

Answer 30

= having too little O2 in your tissues.

Question 31

Tibetans are AKA?

Answer 31

Sherpas.

Question 32

Egs of mammals that have adapted to high elevations? (3)

Answer 32

• Bar-headed goose.
• Yak.
• Llama.

Question 33

Adaptions to respiratory & circulatory system of high altitude species? (3)

Answer 33

• Large hearts.
• Large lungs.
• Increased ability to transport O2 via morphological changes to their Hb.

Question 34

Specialized adaptations of Bar-headed geese to high altitude? (4)

Answer 34

• Larger lungs.
• High blood O2 affinity.
• High capillarized flight muscle fibers with abundant mt.
• High ventilation rates & a breathing pattern that’s effective for gas exchange.

Question 35

General avian traits in Bar-headed geese? (4)

Answer 35

• Thin & strong gas exchange surface with large SA.
• Insensitivity of cerebral blood vessels to hypocapnia.
• Large hearts.
• Lung-air sac ventilation mechanism that’s highly effective for gas exchange.