As the diaphragm contracts, what effect does it have on the thoracic cavity?

As the diaphragm contracts, what effect does it have on the thoracic cavity?

• A. It compresses and shrinks.
• B. It pulls upwards and enlarges.
• C. It pulls downwards and enlarges.
• D. It remains unchanged.

Answer: (C)

When the diaphragm contracts, it moves downward, which increases the volume of the thoracic cavity. This downward movement creates a negative pressure in the thoracic cavity, causing air to be drawn into the lungs as part of the inhalation process. The enlargement of the thoracic cavity allows the lungs to expand, filling with air, which is essential for respiration. This mechanical action is crucial for effective breathing, as it directly influences the pressure dynamics necessary for air movement into and out of the lungs.

When the diaphragm contracts, it moves downward, which increases the volume of the thoracic cavity. This downward movement creates a negative pressure in the thoracic cavity, causing air to be drawn into the lungs as part of the inhalation process. The enlargement of the thoracic cavity allows the lungs to expand, filling with air, which is essential for respiration. This mechanical action is crucial for effective breathing, as it directly influences the pressure dynamics necessary for air movement into and out of the lungs.