Surfactant prevents this collapse by reducing the surface tension of the fluids that line the lungs and helping to equalize the pressures between large and small air spaces. Surface tension is a measure of the attraction molecules of a fluid have for each other.
Buffalo Bill Cody, who later became famous for his Wild West Show, was a rider for the Pony Express and wrote of his experiences. We join Bill's story as he is hired - at the age of 15 - to ride a section of the trail that lies in modern-day Wyoming:
Pony rides are offered daily from 10:00 AM to 5:00 PM near Pioneer Hall at Disneyâs Fort Wilderness Resort & Campground. Riders must be at least 2 years of age, under 80 pounds, no taller than 48 inches and able to hang on by themselves. A parent or guardian must lead the pony at all times. A fee is associated with this activity.