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Authors
Abstract(s)
Desde os primórdios da Humanidade que o ser humano tem olhado com curiosidade para o Espaço que o rodeia. Todavia, a exploração espacial só ganhou novos contornos a partir dos anos 60, altura em que decorreram as primeiras viagens espaciais tripuladas. A microgravidade refere-se à ausência quase completa da sensação de peso, tendo um papel importante na readaptação do corpo humano à exploração espacial, nomeadamente no que diz respeito ao ouvido. O ouvido é um órgão humano responsável pela audição e pelo equilíbrio, sendo a acuidade auditiva a capacidade de distinguirmos entre sons diferentes. A perda de acuidade auditiva é uma das consequências conhecidas das viagens espaciais, sendo, todavia, a etiologia desta perda ainda não muito esclarecida. Nas viagens espaciais, o nível de ruído é muito alto, o que, em conjugação com a vibração induzida a bordo dos objetos espaciais, poderá desempenhar um papel importante no deteriorar da audição dos astronautas. Estudos recentes mostram também que existem alterações significativas das sinapses das células ciliadas do utrículo de mamíferos, pelo que poderá este ser mais um fator que contribui para esta perda de acuidade auditiva. O cérebro humano apresentará também uma certa plasticidade com alterações da substância branca a ocorrer e a desempenhar um papel na diminuição da acuidade auditiva, em articulação com as alterações da distribuição da água livre intracraniana. Por fim, apesar das diferenças biológicas existentes entre os sexos, não parece haver diferenças significativas entre estes no que às alterações da acuidade auditiva diz respeito, sendo, todavia, os resultados atuais nesta área ainda escassos e pouco significativos. Em suma, as alterações da acuidade auditiva com a microgravidade a que os astronautas são expostos no Espaço são ainda pouco estudadas e carecem de um melhor esclarecimento etiológico. À luz do conhecimento atual, pensa-se que a etiologia destas alterações é multifatorial, sugerindo-se que mais trabalhos sejam realizados nesta área.
Since the early days of mankind that human beings have been curious about the Space that surrounds them. However, Space exploration only began in the sixties when the first humans embarked on the first outer space travels. Microgravity refers to the condition where gravity seems to be very small; it has a very important role in human body readaptation to space exploration, namely in the readaptation of the ear. The ear is the human organ responsible for hearing and for balance, with hearing ability being the capacity to distinguish between different sounds. The loss of hearing ability is one of the known consequences of space flights. The etiology of this loss is, however, not well established. In space trips, noise level is very high, which, in combination with motors’ vibration within spacecrafts, may have an important role in astronauts’ hearing deterioration. Recent studies also show that significant changes occur in hair cells of the mammalian utricle, which can be a contributing factor for hearing loss. Human brain also has some plasticity. Changes in white matter, in conjunction with changes in the distribution of intracranial free water, may have a role in the hearing loss. Finally, in spite of biological differences between male and female brains, sex doesn’t appear to affect hearing ability. Nonetheless, the results in this matter are still scarce and with low level of significance. In conclusion, changes in hearing ability as a consequence of microgravity conditions to which astronauts are exposed are still not very well studied and demand a better etiological clarification. In light of the present knowledge, these changes appear to be multifactorial; more studies should be conducted in this area for a better understanding of the mechanisms involved.
Since the early days of mankind that human beings have been curious about the Space that surrounds them. However, Space exploration only began in the sixties when the first humans embarked on the first outer space travels. Microgravity refers to the condition where gravity seems to be very small; it has a very important role in human body readaptation to space exploration, namely in the readaptation of the ear. The ear is the human organ responsible for hearing and for balance, with hearing ability being the capacity to distinguish between different sounds. The loss of hearing ability is one of the known consequences of space flights. The etiology of this loss is, however, not well established. In space trips, noise level is very high, which, in combination with motors’ vibration within spacecrafts, may have an important role in astronauts’ hearing deterioration. Recent studies also show that significant changes occur in hair cells of the mammalian utricle, which can be a contributing factor for hearing loss. Human brain also has some plasticity. Changes in white matter, in conjunction with changes in the distribution of intracranial free water, may have a role in the hearing loss. Finally, in spite of biological differences between male and female brains, sex doesn’t appear to affect hearing ability. Nonetheless, the results in this matter are still scarce and with low level of significance. In conclusion, changes in hearing ability as a consequence of microgravity conditions to which astronauts are exposed are still not very well studied and demand a better etiological clarification. In light of the present knowledge, these changes appear to be multifactorial; more studies should be conducted in this area for a better understanding of the mechanisms involved.
Description
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2019
Keywords
Astronautas Microgravidade Ouvido Audição Etiologia Otorrinolaringologia