The person inhales a lot of water, which soaks the lungs, causing suffocation, unconsciousness and even death. Drowning is the fourth leading cause of accidental death in adults and one of the top three in children. Every year, 500,000 drownings happen in the world.
Among adults, half of accidents are related to alcohol consumption, while in childhood drowning occurs due to lack of parental supervision. Lack of knowledge of the dive site, overconfidence and exhaustion when swimming are other reasons that cause this type of accident.
BY WATER BELOW
In drowning, water enters through the nose, invades the lungs and detonates blood cells.
At the beginning of drowning, the person struggles, trying to stay afloat. She holds her breath as long as she can and involuntarily aspirates small amounts of water, which closes the larynx, an organ located between the windpipe and the base of the tongue. This is our body’s defense mechanism so that water doesn’t flood the lungs.
After a few minutes, the larynx relaxes and the person involuntarily breathes underwater, inhaling and swallowing large amounts of water. Part of the liquid goes to the stomach and the rest follows the same path as the air: it travels through the trachea and reaches the lungs, passing through the bronchi, bronchioles and alveoli.
With a soaked lung, gas exchange (oxygen in and carbon dioxide out) no longer works. The reduction in the oxygen rate causes damage to all tissues, especially those that need more air, such as nerve cells. The brain is severely injured and the person becomes unconscious.
After reaching the alveoli, water enters the blood and penetrates the red blood cells, destroying them. With this, the potassium present in these cells leaks into the blood plasma. In high concentration, potassium is fatal: it eliminates the difference in charge inside and outside the cell, preventing the transmission of nerve impulses and thus muscle contraction. With this, the heart can stop beating.
5With cardiac arrest, the person dies, and the large amount of liquid that enters the body causes the corpse to swell and become heavy, sinking – alive, the body floats because there is air entering the lungs. From then on, the bacteria present in the body begin to proliferate, releasing gases. Then the corpse inflates and floats again
CONSULTANCY: Daniel Muñoz, professor of forensic medicine at the Faculty of Medicine of the University of São Paulo