Respuesta :
Answer:
Option A, diaphragm
Explanation:
Ventilation -- the process of breathing, involving inhalation and exhalation -- in the mediastinum essentially occurs because the lungs and surrounding skeletal muscles function like a vacuum.
When the strip of skeletal muscle seated at the base of the lungs known as the diaphragm contracts then flattens, the intercostal muscles expand the rib cage and the lungs pull air in past nasal and or oral cavities, down the trachea, through the bronchii, and into the lungs. This is the inhalation phase.
Once gas exchange occurs -- oxygen in, carbon dioxide out -- the diaphragm relaxes and returns to its dome-like shape, deflating the lungs and pushing air back up the respiratory tract and into the environment. This is the exhalation phase.
Both inhalation and exhalation in the lungs are results of contractions from the diaphragm, option A.
Final answer:
Inhaling is an active process that relies on the contraction of the diaphragm. This muscle, along with others like the external intercostal muscles, helps expand the thoracic cavity and draw air into the lungs.
Explanation:
Inhaling is an active process that results mainly from the contraction of a muscle called the diaphragm. The diaphragm is a large, dome-shaped muscle below the lungs that separates the thoracic (chest) and abdominal cavities. When the diaphragm contracts, the thoracic cavity expands and the contents of the abdomen are pushed downward. Other muscles, such as external intercostal muscles between the ribs, also contribute to the process of inhalation, especially when inhalation is forced, as when taking a deep breath.
With the chest expanded, there is lower air pressure inside the lungs than outside the body, so outside air flows into the lungs via the respiratory tract.
