Lungs

lung The respiratory organ of air-breathing vertebrates. A pair of lungs is situated in the thorax, within the ribcage. Each consists essentially of a thin moist membrane that is folded to increase its surface area. Exchange of oxygen and carbon dioxide takes place between blood capillaries on one side of the membrane and air on the other. The lung is supplied with air through a bronchus. 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.

Common cold

The common cold usually causes a runny nose, nasal congestion, and sneezing. You may also have a sore throat, cough, headache, or other symptoms. Colds can occur at any time of the year, but they are most common in the winter or rainy seasons. A cold virus spreads through tiny, air droplets that are released when the sick person sneezes, coughs, or blows their nose. You can catch a cold if:
1. A person with a cold sneezes, coughs, or blows their nose near you
2. You touch your nose, eyes, or mouth after you have touched something contamined by the virus, such as a toy or doorknob.
People are most contagious for the first 2 to 3 days of a cold. A cold is usually not contagious after the first week.