In computer networks and telecommunications, a dedicated line is a communications connection or other hardware resource dedicated to a certain application or use. This is different than a shared connection such as a telephone network or the Internet.
Carbon dioxide, a waste product of metabolism, travels from the blood to the alveoli, where it can be exhaled. Between the alveoli is a thin layer of cells called the interstitium, which contains blood vessels and cells that help support the alveoli. The lungs are covered by a thin tissue layer called the pleura. The same kind of thin tissue lines the inside of the chest cavity -- also called pleura. A thin layer of fluid acts as a lubricant allowing the lungs to slip smoothly as they expand and contract with each breath.
The lungs occupy most of the space in the thoracic cavity. The heart sits between the right and left lung. The lungs are soft and spongy because they are mostly air spaces surrounded by the alveolar cells and elastic connective tissue. Each lung is enclosed by a double-layered serous membrane, called the pleura.The visceral pleuron is firmly attached to the surface of the lung. Visceral pleura is continuous with the parietal pleura that lines the wall of the thorax. The small space between the visceral and parietal pleurae is the pleural cavity.he lungs occupy most of the space in the thoracic cavity. The heart sits between the right and left lung. The lungs are soft and spongy because they are mostly air spaces surrounded by the alveolar cells and elastic connective tissue. Each lung is enclosed by a double-layered serous membrane, called the pleura.