ANATOMY

Detailed explanation-1: -Overview. The two lungs are the primary organs of the respiratory system. They sit to the left and right of the heart, within a space called the thoracic cavity. The cavity is protected by the rib cage.

Detailed explanation-2: -The muscular and nervous systems enable the involuntary breathing mechanism. The main muscles in inhalation and exhalation are the diaphragm and the intercostals (shown in blue), as well as other muscles.

Detailed explanation-3: -The diaphragm (DYE-uh-fram) is a muscle between the chest and the abdomen that allows the body to move air in and out of the respiratory system. When you breathe in (inhalation), the diaphragm moves down toward the abdomen, and the rib muscles pull the ribs upward and outward.

Detailed explanation-4: -The two openings of the airway (the nasal cavity and the mouth) meet at the pharynx (pronounced: FAR-inks), or throat, at the back of the nose and mouth. The pharynx is part of the digestive system as well as the respiratory system because it carries both food and air.

Detailed explanation-5: -The diaphragm relaxes during natural exhalation, helping the air to pass out as the lungs deflate. Like the diaphragm, the ribs shield the lungs and expand while we inhale to promote room for the lungs to expand. Then the ribs contract, expelling the air from the lungs.