How does Sherwin B. Nuland use imagery in How We Die, Reflections on Life's Final Chapter?

Imagery:

"So commonly do the coronary arteries betray the heart whose muscle they are meant to sustain, that their treachery is the cause of at least half of all deaths in the United States."

"Like the face of a weather-beaten old man, a heart looks its age. It acts its age as well. There is no need to invoke a disease to explain its failure."

"Cancer, far from being a clandestine foe, is in fact berserk with the malicious exuberance of killing."