page_title: Hypoxic ventilatory response
section_title: High Altitude Adaptation
hierarchical_section_title: Hypoxic ventilatory response / High Altitude Adaptation
caption_attribution_description: English: From left to right; the Andean, Simian, and Tibetan Plateaus have populations that have adapted to their high altitude environments.
context_page_description: Hypoxic ventilatory response is the increase in ventilation induced by hypoxia that allows the body to intake and process oxygen at higher rates. It is initially elevated in lowlanders who travel to high altitude, but reduces significantly over time as people acclimatize. In biological anthropology, HVR also refers to human adaptation to environmental stresses resulting from high altitude.
  In mammals, HVR invokes several physiological mechanisms. It is a direct result of the decrease in partial pressure of oxygen in arterial blood, and leads to increased ventilation. The body has different ways of coping with acute hypoxia. Mammals that rely on pulmonary ventilation will increase their ventilation to account for the lack of oxygen reaching the tissues. Mammals will also experience decreases in aerobic metabolism and oxygen demand, along with increases in ATP production.
  The physiological mechanisms differ in effect and in course of time. HVR is time dependent and can be divided into two phases: the first of ventilation increase, and the second of slow decline.
context_section_description: Populations residing in altitudes above 2,500 meters have adapted to their hypoxic environments. Chronic HVR is set of adaptations found among most human populations historically native to high-altitude regions, including the Tibetan Plateau, the Andean Altiplano, and the Simian Plateau. Up to 140 million people in total reside in such areas, although not all possess these adaptations. Populations that have permanently settled in high altitude locations show virtually no reaction to acute hypoxia. Natives of the Andes and the Himalayas have been shown to develop adaptation to hypoxia from birth to neonatal years in the form of larger lungs and greater gas exchange surface area. This response can be attributed to genetic factors, but the development of the resistance to acute hypoxia is highly affected by when the individual is exposed to high altitude; while genetic factors play an indefinite role in a person’s HVR, because long term migrants do not show reduction in their reactions of high altitude even after living in high altitudes in long term, the discrepancy suggests that reaction to HVR is the combination of environmental exposure and genetic factors.
caption: This image depicts the three high altitude areas where studied populations have adapted to their environment: (From left to right) Andean Altiplano, Simian Plateau, and Tibetan Plateau.[17]
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