AP BIOLOGY

Detailed explanation-1: -When the lungs inhale, the diaphragm contracts and pulls downward. At the same time, the muscles between the ribs contract and pull upward. This increases the size of the thoracic cavity and decreases the pressure inside. As a result, air rushes in and fills the lungs.

Detailed explanation-2: -Contraction of these muscles raises the rib cage upward and outward, thereby contributing to the expansion of the thoracic cavity and reduction of pressure within the lung, causing air to move from the air into the lungs (see Figure 6.1. 3).

Detailed explanation-3: -During inhalation, the diaphragm is relaxed, allowing the lungs to expand. The innermost intercostal muscles relax, while the external intercostal muscles contract, causing the chest cavity to expand. This expansion allows the lungs to fill with air, due to the negative pressure created by the extra space.

Detailed explanation-4: -When you breathe in (inhalation), the diaphragm moves down toward the abdomen, and the rib muscles pull the ribs upward and outward. This makes the chest cavity bigger and pulls air through the nose or mouth into the lungs.

Detailed explanation-5: -Primary Muscles The primary inspiratory muscles are the diaphragm and external intercostals. Relaxed normal expiration is a passive process, happens because of the elastic recoil of the lungs and surface tension.