Closer look of alveoli
Alveoli are the tiny air sacs in the lungs at the end of the smallest airways, where the exchange of oxygen and carbon dioxide takes place
Anatomy of a human lung
At the bottom of the trachea, or windpipe, there are two large
tubes. These tubes are called the main stem bronchi, and one heads
left into the left lung, while the other heads right into the right lung. Each main
stem bronchus – the name for just one of the bronchi – then branches off into tubes
or bronchi that get smaller and even smaller still, like branches on a big tree. The tiniest tubes are called bronchioles and there are about 30,000
of them in each lung. Each bronchiole is about the same thickness as a hair.
the end of each bronchiole is a special area that leads into clumps of teeny tiny
air sacs called alveoli. There are about 600 million alveoli in
your lungs and if you stretched them out, they would cover an entire tennis court. Each alveolus – what we call just one of the alveoli – has a mesh
– like covering of very small blood vessels called capillaries. These capillaries are so tiny that the cells in your blood need to line up single
file just to march through them.