A person may bleed from the nose when at a great height above the sea level. With reference to this, which one of the following statements is correct ?

At sea level, the internal blood pressure within human capillaries is balanced by the external atmospheric pressure. As one ascends to a great height, the atmospheric pressure decreases rapidly [1]. Specifically, the air pressure drops by approximately 1 mb for every 10 meters of elevation. While the external pressure decreases, the internal hydrostatic pressure exerted by the blood in the capillaries remains relatively constant or does not drop at the same rate [2]. Consequently, the pressure exerted by the blood becomes significantly higher than the surrounding atmospheric pressure [3]. This pressure gradient creates a net outward force on the thin walls of the nasal capillaries, which are particularly delicate and close to the surface. The resulting imbalance causes these vessels to rupture, leading to epistaxis or nosebleeds [3].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 23: Pressure Systems and Wind System > Vertical Variation of Atmospheric Pressure > p. 305
2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 9: Atmospheric Circulation and Weather Systems > Vertical Variation of Pressure > p. 76
3. [3] https://www.sciencedirect.com/topics/medicine-and-dentistry/capillary-pressure