These are essential for the exchange of oxygen in the blood: when they break down, the lung loses its elasticity and there is less surface in the lung to absorb oxygen.
(they; break down; ) (the lung; loses; its elasticity; T:when they break down) Context(the lung loses,List([83, 97))):(These; are; essential for the exchange of oxygen in the blood)
the lung loses,List([83, 97))
they the lung These
break down loses are
its elasticity T:when they break down
essential for the exchange of oxygen in the blood