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.

Detailed explanation-2: -In addition to helping you breathe, your diaphragm increases pressure inside your abdomen. This helps with other important functions, such as getting rid of your urine (pee) and feces (poop). It helps prevent acid reflux by putting pressure on your esophagus (food tube in your throat).

Detailed explanation-3: -As the diaphragm contracts (moves downward), the volume of the thoracic cavity increases and the intra-alveolar pressure decreases from an atmospheric pressure of 760mmHg to   756mmHg. A pressure gradient is established and air enters the lungs. The external intercostal muscles also assist inspiration.

Detailed explanation-4: -Lung volume expands because the diaphragm contracts and the intercostals muscles contract, thus expanding the thoracic cavity. This increase in the volume of the thoracic cavity lowers pressure compared to the atmosphere, so air rushes into the lungs, thus increasing its volume.

Detailed explanation-5: -The correct option is A True. Inhalation: The diaphragm and intercostal muscles (the muscles that link the rib cage) contract during inhalation, causing the lung capacity to expand and the thoracic cavity to enlarge.