Altitude Flashcards
Why does pO2 decrease as altitude increase?
Barometric pressure decreases exponentially as altitude increases and proportion of atmospheric pO2 is constant => alveolar and arterial pO2 fall, causing hypoxic hypoxia (induces hyperventilation)
Why do integrated changes in ventilation occur?
Due to changes in activity and environment e.g. exercise, respiratory illness, exposure to high altitudes
What does prolonged exposure to hypobaric conditions cause?
Physiological changes that allow an individual to acclimatise to the “hostile” environment.
How does pO2 change through the respiratory system?
Decrease at each stage of oxygen transport - oxygen is passing down a cascade of pp from atmosphere to tissues.
Reduction in difference between inspired and alveolar air - increased minute ventilation, hyperventilation in visitor at 3000m due to stimulation of peripheral chemoreceptors of carotid and aortic bodies.
What are the acclimatisation difference in a low altitude native?
Develop changes within the first few hours or days which are on-going over weeks and moths. Can be seen long-term in the visitor but may be different to a person who lives and was born at high altitude. After several days, the minute ventilation will begin to increase. The time taken for secondary rise in ventilation to reach maximum increases with increasing altitude. When visitor returns to sea level, there is declimatisation.
What is the difference between high altitude and low altitude natives?
HAN ventilation higher. Relative decrease in ventilation is adaptive so HAN uses less energy consuming methods for hypoxic conditions e.g. more efficient pulmonary gas exchange.
Shows little change in ventilation ver a wide range of pO2 but a v low pAI2 will still induce an increase in ventilation.
Pulmonary diffusions capacity in HAN greater at rest by 20-30% probably due to increase in alveolar SA and increase in pulmonary blood volume
