Write the events that occur during the process of breathing in humans.
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Breathing in humans is divided into 2 steps:
  1. Inhalation: In the process of inspiration, there would be a contraction of muscles attached to the ribs on the outer side which pulls out the ribs and results in the expansion of the chest cavity. Later, the diaphragm, contracts, moves downwards and expands the chest cavity resulting in the contraction of the abdominal muscles. The expansion of the chest cavity produces a partial vacuum which sucks air into the lungs and fills the expanded alveoli.
  2. Exhalation: The expiration process is considered once after the gaseous exchange occurs in the lungs and the air is expelled out. This expulsion of air is called expiration. During this process, muscles attached to the ribs contract, the muscles of the diaphragm and the abdomen relax which leads to a decrease in the volume of the chest cavity and increases the pressure of the lungs, causing the air in the lungs to be pushed out through the nose.
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