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.
Each lung is encased in a sack of tissue called the pleura. The lung is stuck to this sack by a small amount of liquid, which creates surface tension. It creates a very smooth surface so that as the lungs expand and contract they can ride over the heart and surrounding elements.ach lung is encased in a sack of tissue called the pleura. The lung is stuck to this sack by a small amount of liquid, which creates surface tension. It creates a very smooth surface so that as the lungs expand and contract they can ride over the heart and surrounding elements.