The ozone layer and the structure of the upper atmosphere
A complex multi-level gas envelope surrounds the planet's surface. The ozone layer is of particular biological importance. Although its thickness is only a few millimeters, this shield, formed by oxygen molecules, plays a critical role in preserving life on the planet.
Above the stratosphere, the air envelope has a clear gradation. Studying these remote altitudes is of immense interest to space medicine, especially in the context of life support for astronauts in extreme conditions:
- Mesosphere: characterized by severe air rarefaction and extends up to an altitude of 80 kilometers.
- Thermosphere: begins at an altitude of 80–90 km. Here, a pronounced temperature rise is observed up to altitudes of 200–300 km, where it reaches extreme values of about 1500 K (a change of 1 K is equivalent to 1 °C). Above this mark, the temperature remains virtually unchanged.
- Ionosphere: a massive layer of ionized air. Its boundaries are extremely unstable and vary within 500–1000 km depending on the specific time of day and season.
- Exosphere: a layer that extends into outer space up to an altitude of 3000 km.
- Magnetosphere: ranges from 3,000 to 50,000 km and forms the ultimate upper boundary of the Earth's atmosphere.
Biological and ecological role of the air environment
Atmospheric air acts as a fundamental environmental factor. The human body is in a constant and inseparable connection with the surrounding gas. The average time during which life is possible without an air supply is extremely short, about 5 minutes, after which irreversible death occurs.
Global functions of the air environment include:
- Respiration support: uninterrupted supply of oxygen to all living organisms, necessary for cellular metabolism.
- Heat exchange: implementation of thermoregulation processes, allowing the body to release excess heat through various pathways.
- Transmission of solar radiation: the atmosphere acts as a filter, transmitting the most important optical part of the spectrum to the planet's surface, including visible light, ultraviolet (UV), and infrared (IR) rays.
- Retention of the Earth's thermal radiation: formation of the so-called greenhouse effect. The atmosphere prevents excessive cooling of the planet by trapping IR radiation with water vapor, carbon dioxide, and ozone.
- Spatial orientation: air serves as a physical medium for the unhindered transmission of sound waves and visual signals perceived by sensory organs.
Mechanisms of body adaptation
Over the course of long evolutionary development, the human body has developed a complex set of adaptive mechanisms enabling it to function optimally in the terrestrial air environment. These mechanisms are tuned to specific physicochemical parameters of the atmosphere.
However, this system has its limits of endurance. If normal air properties undergo sharp, abrupt changes, the defense systems cannot adapt in time. This inevitably leads to a breakdown of adaptation and, consequently, triggers a cascade of reactions forming various pathological conditions.
Briefly: answers to topical questions
What are the characteristics and altitude boundaries of the mesosphere and thermosphere?
The characteristics and altitude boundaries of the mesosphere and thermosphere are determined by their location above the stratosphere, the degree of rarefaction, and the temperature regime.
- Mesosphere — a rarefied layer that extends up to an altitude of 80 km.
- Thermosphere — a layer starting from 80–90 km. The temperature within it rises up to altitudes of 200–300 km, reaching ~1500 K (where a change of 1 K = 1 °C), and then remains almost constant up to great heights.
MTIEM — the order of layers above the stratosphere: Mesosphere, Thermosphere, Ionosphere, Exosphere, Magnetosphere.
Class and exam questions
Why does medicine need to study the exosphere and magnetosphere?
This knowledge is critically important for space medicine to ensure the safety and vital activity of cosmonauts under extreme conditions.
What are the consequences of a sharp change in the habitual properties of air for humans?
Sharp fluctuations in the parameters of the gas environment cause a breakdown of evolutionary adaptation mechanisms, leading to the development of pathologies.
Through which components does the atmosphere retain the Earth's thermal radiation?
The greenhouse effect and the retention of infrared radiation are ensured by the presence of water vapor, carbon dioxide, and ozone in the air.
What else to study on this topic
- Physiology of thermoregulation and heat loss pathways into the air environment
- Pathogenesis of conditions in acute oxygen deficiency (asphyxia)
- Basics of space medicine and life support systems
- Biological effects of ultraviolet and infrared radiation spectra on the skin
Master the entire topic in the "Hygiene" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "The impact of atmospheric air pollution on human health" and 530 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 95 video lessons for the subject
Other topics in "Chapter 1. Ecological and hygienic problems of atmospheric air"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.