MEDICAL BIOLOGY, ANATOMY, HUMAN PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

CHAPTER 6. THE RESPIRATORY PROCESS AND ITS PATHOLOGY

RESPIRATION UNDER VARIOUS CONDITIONS

2. RESPIRATION AT REDUCED ATMOSPHERIC PRESSURE

When ascending to high altitudes (mountaineers, parachutists), a person is exposed to reduced atmospheric pressure, which results in a decreased oxygen intake and The Development of Hypoxia.

Hypoxia develops already at an altitude of 2.5–3 km above sea level, stimulating the carotid chemoreceptors. This triggers hyperventilation, characterized by deep and frequent breathing.

With further ascent to 4–5 km, atmospheric pressure drops significantly, leading to altitude sickness. The primary cause of this condition is a sharp decrease in Blood carbon dioxide tension (due to its intensive elimination during hyperventilation). Since carbon dioxide acts as a respiratory stimulant, its reduced levels cause a sharp decrease in breathing depth. Hypoxia leads to weakness, elevated blood pressure, headaches, and loss of consciousness. Breathing pure oxygen through a mask allows individuals to maintain physical performance even at altitudes of 11–12 km.

Prolonged stay in mountainous regions leads to acclimatization to hypoxia. In such individuals, the erythrocyte count and Hemoglobin levels in the blood increase, the tolerance of Nerve Cells to hypoxia improves, and pulmonary ventilation rises.



Last update: 08/08/2026

Editorial and Educational Adaptation: This material has been compiled based on the primary/original source text. The project team performed an editorial review, corrected technical inaccuracies, structured sections, and adapted the content for an educational format.

What was processed:

  • elimination of formatting defects (OCR errors, structural breaks, corrupted characters);
  • editorial organization of content;
  • standardization of terminology in accordance with academic sources;
  • verification of factual statements against the original source text.

All mentions of the author, publication year, and origin of the primary text have been preserved in accordance with the source.