Differing Mechanisms of High Altitude Adaptation Flashcards
How long have the Andean population lived at HA?
Andean pop. have lived at HA for 3,000 years
How long have the Tibetan population lived at HA?
Tibetan pop. have lived at HA for 25,000 years
What changes occur to respiratory features in the Tibetan population compared to acclimitised lowlanders?
Increased TLC/RV/FEV1/Minute ventilation/Diffusing capacity
Decreased A-aO2 gradient
What changes occur to oxygen carriage in the Tibetan population compared to acclimitised lowlanders?
Decreased Hb, viscosity, SaO2
Oxygen affinity (curve) unchanged
Decreased oxygen content of blood per litre
What are two single nucleotide polymorphisms at high frequency in Tibetans?
PHD2 & HIF2a are polymorphisms which have been suggested as causal in low Hb
How do Tibetans achieve increased BV?
Increased plasma volume (decreased viscosity)
How do Andeans achieve increased BV?
Increased Hct (increased viscosity)
Significance of increased NO metabolites in Tibetan pop.
Increased vasodilation = increased BF
What happens to PAP in Tibetans?
Decreased PAP compared to acclimitised lowlanders
Why is increased myoglobin important in Tibetan pop?
Increased solubility of O2 which results in easier diffusion of O2 into mitochondria
Why is decreased cross sectional area of fibres important in Tibetan pop?
Distance of O2 diffusion reduced, closer to capillaries for easy diffusion
What happens to appetite when sea-level natives travel to high altitude?
Loss of appetite when SL natives travel to HA
Which adaptation is more advantageous between Tibetans & Andeans?
Tibetan adaptation more advantageous based on decreased viscosity
How do Tibetans increase O2 delivery at HA?
Tibetans increase O2 delivery at HA by increasing CO and tissue blood flow
