Bronchi And Bronchioles

The windpipe divides into two smaller tubes called bronchi. The two bronchi enter lungs and are also made of hoops of cartilage and have the same lining as the windpipe. The bronchi divide in to many smaller tubes called bronchioles. These have a diameter of about 1 mm.

The bronchioles divide many times. They have walls made of muscles can make the bronchiole diameter narrower or wider. Terminal bronchioles divide into narrower respiratory bronchioles.

These tiny airways end in a cluster of alveoli that looks like a bunch of grapes through which oxygen enters the bloodstream. Squeezed into the chest, all those alveoli provide a surface area for absorbing oxygen.