Comparative Anatomy of the Respiratory Systems in High Altitude vs. Low Altitude Populations
Article Sidebar
Main Article Content
Abstract
Background: The comparative anatomy of the respiratory systems in high-altitude versus low-altitude populations offers significant insights into human adaptation to hypoxic conditions. High-altitude populations, exposed to chronic hypobaric hypoxia, exhibit distinct physiological adaptations that enhance oxygen uptake, transport, and utilization. This study investigates these adaptations by comparing the respiratory systems of high-altitude and low-altitude residents.
Objective: To compare the respiratory anatomy and function between high-altitude and low-altitude populations, elucidating the physiological adaptations to chronic hypoxia.
Methods: A cross-sectional survey was conducted at the University Institute of Physical Therapy, University of Lahore, Pakistan. The study included 200 participants, with 100 individuals from high-altitude regions (>2,500 meters) and 100 from low-altitude regions (sea level). Inclusion criteria required participants to be aged 18-60 years, non-smokers, and free from chronic respiratory or cardiovascular diseases. Data collection involved medical history interviews, physical examinations, spirometry to measure forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), chest radiographs to evaluate lung volumes and structural differences, and blood tests for hemoglobin concentration. Respiratory muscle strength was assessed using maximal inspiratory and expiratory pressures. Statistical analysis was performed using SPSS version 25, with independent t-tests and chi-square tests used for comparisons, and multivariate regression analysis to adjust for confounders.
Results: The high-altitude group demonstrated significantly higher hemoglobin levels (17.5 ± 1.2 g/dL) compared to the low-altitude group (14.2 ± 1.1 g/dL, p < 0.001). Lung volumes, including FVC (4.8 ± 0.7 L vs. 4.1 ± 0.6 L, p < 0.001) and FEV1 (4.0 ± 0.5 L vs. 3.4 ± 0.4 L, p < 0.001), were significantly greater in the high-altitude group. Total lung capacity was also higher (6.3 ± 0.8 L vs. 5.5 ± 0.7 L, p < 0.001), as was alveolar surface area (130 ± 15 m² vs. 110 ± 10 m², p < 0.001). Respiratory muscle strength measurements showed higher maximal inspiratory pressure (130 ± 20 cmH₂O vs. 110 ± 18 cmH₂O, p < 0.001) and maximal expiratory pressure (160 ± 22 cmH₂O vs. 140 ± 20 cmH₂O, p < 0.001) in the high-altitude group.
Conclusion: High-altitude populations exhibit significant respiratory adaptations, including increased lung volumes, enhanced alveolar surface area, higher hemoglobin concentrations, and improved respiratory muscle strength, to cope with chronic hypoxia. These findings enhance the understanding of human adaptation to extreme environments and have implications for medical practice in managing hypoxia-related conditions.
Keywords: High-Altitude Adaptation, Respiratory System, Chronic Hypoxia, Lung Volumes, Hemoglobin Concentration, Respiratory Muscle Strength, Physiological Adaptations, Hypobaric Hypoxia
Article Details
This work is licensed under a Creative Commons Attribution 4.0 International License.
References
Beall CM. Two routes to functional adaptation: Tibetan and Andean high-altitude natives. Proc Natl Acad Sci U S A. 2007 Sep 18;104 Suppl 1:8655-60.
Bigham AW, Lee FS. Human high-altitude adaptation: forward genetics meets the HIF pathway. Genes Dev. 2014 Jun 1;28(20):2189-204.
Gilbert-Kawai ET, Milledge JS, Grocott MP, Martin DS. King of the mountains: Tibetan and Sherpa physiological adaptations for life at high altitude. Physiology (Bethesda). 2014 Mar;29(3):388-402.
MacInnis MJ, Wang P, Koehle MS, Rupert JL. The genetic basis of altitude adaptation. Mol Genet Genomics. 2017 Apr;292(6):991-1002.
Moore LG, Charles SM, Julian CG. Humans at high altitude: hypoxia and fetal growth. Respir Physiol Neurobiol. 2011 Aug 1;178(1):181-90.
Simonson TS. Altitude adaptation: a glimpse through various lenses. High Alt Med Biol. 2015 Jun;16(2):125-37.
Storz JF, Scott GR, Cheviron ZA. Phenotypic plasticity and genetic adaptation to high-altitude hypoxia in vertebrates. J Exp Biol. 2010 Jun;213(Pt 16):4125-36.
Gassmann M, Muckenthaler MU. Adaptation to hypoxia in high-altitude dwellers. Front Genet. 2015 Jul 22;6:122.
Niermeyer S, Andrade Mollinedo P, Huicho L. Child health and living at high altitude. Arch Dis Child. 2009 Sep;94(10):806-11.
Beall CM, Laskowski D, Strohl KP, Soria R, Villena M, Vargas E, et al. Pulmonary nitric oxide in mountain dwellers. Nature. 2001 May 24;414(6862):411-2.
Grocott MP, Martin DS, Levett DZ, McMorrow R, Windsor J, Montgomery HE. Arterial blood gases and oxygen content in climbers on Mount Everest. N Engl J Med. 2009 Jan 8;360(2):140-9.
Lundby C, Calbet JA, Robach P. The physiological response to hypoxia: the result of 50,000 years of evolution. Exp Physiol. 2009 May;94(5):377-88.
West JB. Physiological effects of chronic hypoxia. N Engl J Med. 2017 Sep 14;377(11):1070-1.
Yi X, Liang Y, Huerta-Sanchez E, Jin X, Cuo ZX, Pool JE, et al. Sequencing of 50 human exomes reveals adaptation to high altitude. Science. 2010 Jul 2;329(5987):75-8.
Zubieta-Calleja GR, Zubieta-Calleja L, Paulev PE. Altitude adaptation through hematocrit changes. J Physiol Pharmacol. 2006 Dec;57 Suppl 4:431-42.
Ward MP, Milledge JS, West JB. High Altitude Medicine and Physiology. 5th ed. CRC Press; 2013.
Weitz CA, Garruto RM. The human adaptive response to high altitude: an evolutionary perspective. Anthropol Rev. 2015 Jul;78(1):21-43.
Bigham AW. Genetics of human origin and evolution: high-altitude adaptations. Curr Opin Genet Dev. 2016 Dec;41:8-13.
West JB. High-altitude adaptations: lung and pulmonary circulation. Compr Physiol. 2012 Oct;2(4):2113-31.
Petousi N, Robbins PA. Human adaptation to the hypoxia of high altitude: the Tibetan paradigm from the pregenomic to the postgenomic era. J Appl Physiol (1985). 2014 Dec 15;116(7):875-84.