Oxygen. Significance of Oxygen in Biosphere

In the nature the processes of oxygen consumption and excretion constantly take place. The consumption of oxygen occurs at respiration of human and animals, at burning, different oxidizing processes, etc. However, its content in the atmosphere remains practically constant due to its excretion by phytoplankton of oceans and green plants.

For a person oxygen is necessary for oxidizing biochemical processes in organism. At lack of oxygen in organism hypoxia of various degree of severity occurs. It is not the percentage but absolute amount of О2 in the air, depending on its partial pressure (part of the atmospheric pressure for the given gas) is of great importance for a person. Partial pressure of oxygen decreases at cyclones and also at climbing a height.

Pathogenesis, Symptomatology, Prevention of Mountain (High-Altitude) Illness

This disease may be encountered in mountaineers, inhabitants of mountains and pilots.

Pathogenesis: It is a decrease of partial pressure of oxygen in the air at ascending heights and decrease of partial pressure of oxygen in the alveolar air. Amount of oxygen entering organism depends on gradient G (difference between the partial pressure of oxygen in the alveolar air (Pair) and in blood (Pblood):

 

G = Р in air / Р in blood

 

On ascending heights Pair decreases. If gradient of pressure decreases, hypoxia of various degree of severity occurs.

 

The following zones of oxygen pressure affecting a human organism are distinguished:

v Inert — up to 2 km → it is safe for health

v Complete compensation — up to 4 km → increase of lung ventilation, minute volume of blood

v Incomplete compensation — up to 5.5 km → headache, euphoria, sleepiness, memory impairment

v Critical — up to 8 km → loss of consciousness

v Threshold of mortality — higher than 8 km → death.

Height of 8 km is a death threshold.

Symptomatology of Mountain Illness

Acute, subacute (in climbers) and chronic (in inhabitants of high-mountainous settlements) forms of mountain illness of a mild, moderate and severe degree are distinguished, e.g. high-mountainous lung hypostasis.

The symptoms of the disease are dyspnea, palpitation, malaise, fatigability, sleepiness, nausea, vomiting, nasal bleeding, skin cyanosis.

Prophylaxis of Mountain Illness

· A step-by-step (gradual) climbing mountains with making camps for the development of compensatory reactions to hypoxia (development of physiological erythrocytosis).

· Usage of oxygen apparatuses by pilots of planes

· Cabin pressurization of planes

 

Ozone is anallotropic form of oxygen having formula О3.

The ozone layer in atmosphere is located at a height of 20-30 km. Ozone absorbs a space short-wave radiation, including ultraviolet (UV) radiation. The decrease of ozone layer by 20 % due to anthropogenic and natural factors results in "ozone gaps" which in their turn cause the increase of UVR leading to growth of skin melanoma in people. Ozone has high oxidizing properties reducing chemical and microbe pollution of atmosphere.

Nitrogen. Significance of Nitrogen in Biosphere

Nitrogen is a part of some proteins and nitrogenous compounds. It is the basis of all living beings on our planet. However, living organisms cannot receive nitrogen directly from the atmosphere, except for some bacteria and blue-green seaweeds. Then nitrogenous compounds through food chains pass into other organisms.

Effect of Nitrogen on Organism

Nitrogen under normal conditions (the normal atmosphere pressure) is an inert gas (no effect on organism). At the increased pressure nitrogen produces a narcotic effect on the CNS (it is proved by laboratory tests on animals). In divers on the depth of 100 m in 5 minutes dizziness, euphoria, spotty memory defect, hallucination occur.