Adaptation Flashcards
What is adaptation?
Adaptation is the compensatory changes observed in populations native to high altitude for many generations that facilitate existence at reduced barometric pressure (reduced PIO2)
Examples of high altitude populations > 2500m
Andes
Tibet
East Africa
What is the most studied pattern of high altitude and why?
The Andean pattern due to the high-altitude research laboratory at Morococha Peru (4540m)
What happens adapted PCO2 at high alt?
Adapted PCO2 is lower than sea-level values (hypocapnic)
What happens adapted PO2 at high alt?
Adapted PO2 is lower than sea-level values (hypoxic)
What happens adapted SaO2 at high alt?
Adapted SaO2 is lower than sea-level
What happens adapted Hb at high alt?
Adapted Hb is higher than sea-level
What happens adapted Hct at high alt?
Adapted Hct is higher than sea-level
Which gender has a higher ventilation at high altitude?
Males have a greater ventilation at high altitude
Who has higher ventilation, sea-level or high-altitude dwellers?
Highland dwellers have a higher rate of ventilation than sea-level at rest
What is the isocapnic hypoxic ventilatory response?
?
Adaptations of high-altitude dwellers
Higher ventilation at rest
Higher exercise ventilation
Higher/similar hypoxic ventilatory response
Higher SaO2 at rest and during exercise
How do the lungs adapt to high altitude?
Higher vital capacity
Higher FEV1 & max expiratory flow rate
Higher diffusing capacities
Lower A-aO2 gaps
What study found O2 environment responsible for body size?
Drosophila - normoxia grew larger than hypoxia, high O2 sat animal grew even larger
How do haemodynamics vary between HA and SL adults?
Increased Hb, PAP and PVR in HA adults compared to SL
Decreased SaO2 in HA adults
How does RV vary compared to LV in Andean population?
RV increased in size relative to left in HA population (ECG, CXR, Postmortem studies)
How does HVR alter vessels in HA adapted population?
Increased load = increased size, therefore, increased thickness, media and adventitia
During exercise, how do haemodynamics of HA change?
Increased HR
Increased CI
Increased SI
Increased PPA
Increased PVR
How do Andeans increased O2 delivery at HA?
Andeans increase O2 delivery at HA predominantly by increasing Hb concentration and thus O2 content of blood
How did SaO2 change in HA natives that moved to SL for two years?
SaO2 increased meaning ventilation had not been impaired
How did PVR change in HA natives that moved to SL for two years?
PVR reduced but not as low as you expect, meaning there could be irreversible changes as a result of adaptation
How did the cardiovascular responses of pika (HA mammals) compare to rats exposed to HA?
No significant difference in HR or PSA
PPA of pika lower at every altitude, indicating that PPA is not increased in adapted animals
How did the vessel remodelling of pika (HA mammals) compare to rats exposed to HA?
Pika vasculature remains unchanged, however, rats at HA have alterations including increased thickness, media & adventitia
Alterations in HA adapted animals
Normal PAP
Normal RV size
Blunted HPV
Normal Hct
Maintain higher PaO2 than sea-level animals at HA
