Question

During inhalation, the pressure in the lungs is slightly less than external pressure and the muscles controlling exhalation are relaxed. Under water, the body equalizes internal and external pressures. Discuss the condition of the muscles if a person under water is breathing through a snorkel. Would a snorkel work in deep water?

Answer 1

During inhalation, the diaphragm moves downward, reducing the pressure inside the lungs, allowing air to enter. During exhalation, the muscles relax, and the surface tension in the alveoli creates a positive pressure, forcing air out. Breathing through a snorkel underwater would make it difficult to expel air effectively.

Step-by-step explanation:

During inhalation, the muscles expand the chest and the diaphragm moves downward, reducing the pressure inside the lungs to less than atmospheric pressure. This pressure difference allows air to rush into the lungs. During exhalation, the muscles relax, and the surface tension in the alveoli creates a positive pressure inside the lungs, forcing air out. If a person is breathing through a snorkel underwater, the muscles controlling exhalation would still be relaxed because the pressure between the chest wall and lungs needs to remain negative to keep them attached. However, the pressure inside the lungs would equalize with the external pressure, making it difficult to expel air effectively through the snorkel.

Answer 2

Underwater, the muscles used for breathing through a snorkel work to equalize lung and external pressure. A snorkel is ineffective in deep water because the water pressure exceeds what lung expansion can overcome. Thus, snorkeling is only viable in shallow water.

Step-by-step explanation:

Understanding Breathing Underwater with a Snorkel

When a person breathes underwater using a snorkel, the muscles involved in respiration function differently than they do on land. The pressure within the lungs must equalize with the water pressure, which can be much greater than atmospheric pressure. During inhalation, muscles such as the diaphragm and rib cage expand the chest cavity, creating a negative gauge pressure that draws air in through the snorkel. However, the function of these muscles is limited by the snorkel's length and the depth of water.

A snorkel cannot be used in deep water due to the increasing water pressure with depth, which significantly exceeds the pressure humans can compensate for by expanding their lungs. At greater depths, the surrounding water pressure would prevent the muscles from expanding the chest cavity effectively, and without additional equipment like a scuba tank and regulator, it becomes impossible to inhale through a snorkel. The diaphragm and rib cage would face undue pressure, and without the proper pressure differential, air could not be drawn into the lungs.

Despite the body's natural capability to equalize pressures, the limited length of a snorkel makes it impractical and unsafe to use beyond shallow water. Additionally, exhalation underwater through a snorkel is primarily passive due to the elasticity of the lungs, although muscle action can add to this positive pressure to produce forced exhalation if needed.