Which airway directly delivers air to the lobule

Authors Authors and affiliations Martin Caon. Chapter First Online: 04 August This is a preview of subscription content, log in to check access. Martin Caon 1 1. Personalised recommendations. They are protected inside the thoracic cage. The left lung has two lobes and is slightly smaller in volume than the right. It curves in at the cardiac notch to accommodate the heart. The right lung has three lobes. It is slightly shorter, because the diaphragm muscle sits higher below it to accommodate the liver.

During inhalation, air flows into the lungs through the bronchi and bronchioles. Oxygen from the air is then absorbed into the bloodstream: it passes through millions of microscopic sacs, the alveoli, into surrounding capillaries. Carbon dioxide waste diffuses the opposite way, from the capillaries to the alveoli.

The lungs expel the deoxygenated air during exhalation. Alveoli are microscopic air sacs served by the bronchioles. Hundreds of millions of alveoli exist inside each lung. They are the terminal ends of the respiratory tract and the sites of external respiration—the exchange of gases between the air and the bloodstream.

During inhalation, the alveoli fill with air from the bronchioles. Oxygen diffuses through the alveoli into networks of pulmonary capillaries that surround them, and is pumped through the bloodstream.

Carbon dioxide from deoxygenated blood diffuses from the capillaries into the alveoli, and is expelled through exhalation. The lungs sit atop the diaphragm, a muscle that forms the floor of the thoracic cavity. The action of the diaphragm is key to the physical process of breathing. During inhalation, the diaphragm contracts and moves inferiorly, toward the abdominal cavity.

They are separated from each other by the mediastinum , which contains the heart. The only point of attachment for each lung is at the hilum , or root, on the medial side. This is where the bronchi, blood vessels, lymphatics, and nerves enter the lungs. The right lung is shorter, broader, and has a greater volume than the left lung. It is divided into three lobes and each lobe is supplied by one of the secondary bronchi.

The left lung is longer and narrower than the right lung. It has an indentation, called the cardiac notch, on its medial surface for the apex of the heart. The left lung has two lobes.