How does Thomas Harris use imagery in Red Dragon?

Imagery:

"There was an opinion he wanted. A very strange view he needed to share; a mindset he had to recover after his warm round years in the Keys. The reasons clacked like roller-coaster cogs pulling up to the first long plunge, and at the top, unaware that he clutched his belly, Graham said it aloud. 'I have to see Lecter."'

"Throat seared with smoke. BONG BONG. Door here. Under the knob. Don't drop it. Click the lock. Snatch it open. Air. Down the ramp. Air. Collapsed in the grass. Up again on hands and knees, crawling."