Adaptations to Altitude

Question 1

What are the physiological challenges of high altitude?

Answer 1

• Cold + windy
• Dry, affect water balance
• High UV levels
• PO2 low

Question 2

How do you calculate the partial pressure of O2?

Answer 2

21% x atmospheric pressure
E.g. 0.21 x 418 mmHg = 88 mmHg

Question 3

Why does O2 diffuse slower at high altitude?

Answer 3

Lower partial pressure difference

Question 4

What are some symptoms of acute mountain sickness?

Answer 4

• headache
• nausea & dizziness
• loss of appetite
• fatigue
• shortness of breath
• decreased coordination
• impaired vision
• nausea + vomiting
• unconsciousness, convulsions + death

Question 5

What are the 5 stages to supply tissues with O2?

Answer 5

• Ventilation of lungs
• Diffusion in lungs from air to blood
• O2 transport in blood
• O2 diffusion from blood to tissues
• Tissue utilisation of O2

Question 6

What can affect oxygen tension in inhaled air through the stages of supplying tissues with O2?

Answer 6

Barometric pressure

Question 7

What is the oxygen cascade?

Answer 7

The change in PaO2 as oxygen moves from lungs to cells

Question 8

What is one of the first responses to hypoxia?

Answer 8

Increase respiration + tidal volume (hyperventilation) to extract O2 from ‘thin’ air

Question 9

What can hyperventilation lead to?

Answer 9

Removal of CO2, leading to alkalosis, decreased ventilation, build up of CO2 = hyperventilation
- Can lead to cycles of increased + decreased respiration

Question 10

What is polycythaemia?

Answer 10

An increase in the production of red blood cells from about 5 million/ml blood to about 8 million

Question 11

What is the effect of DPG?

Answer 11

Reduces affinity of haemoglobin for oxygen, thus facilitating its release to the tissues

Question 12

What is angiogenesis?

Answer 12

Increase in number of capillaries per unit tissue volume, which reduces diffusion distance for oxygen between blood and tissues

Question 13

Why does myoglobin concentrations increase at high altitudes?

Answer 13

Facilitates diffusion of O2 to tissues

Question 14

Adaptions on diffusion from air to blood in lungs?

Answer 14

• larger lung volumes = greater lung SA
  = increases of Hb, alveolar volumes + membrane diffusion

Question 15

How are llamas adapted to high-altitude environments?

Answer 15

• Hb has high affinity for O2 (lies left to the normal curve)

Question 16

Why is having a high affinity for O2 more beneficial than a low affinity in the llama?

Answer 16

Llama Hb more willing to release but harder to pick up
PO2 is lower in environment than in tissues

Question 17

Do Deer mice have a higher or lower affinity to O2?

Answer 17

Lower (lies right of the curve )