The presence of this substance in areas of the body where it should not be is easily detectable on X-rays, on which this substance appears dark. For 10 points each:
[10e] Name this substance. The prefix “pneumo-” denotes the abnormal presence of this substance, as in a pneumothorax, when this substance in the chest cavity can collapse a lung.
ANSWER: air [or obvious equivalents]
[10m] Hamman’s crunch signals pneumo·mediastinum (“media-STY-num”), which is often caused by Boerhaave syndrome, or a transmural tear of this structure. In contrast, Mallory–Weiss tears of this structure are not full-thickness.
ANSWER: esophagus
[10h] Portal venous gas and pneumatosis intestinalis are pathognomonic for this frightening condition, which disproportionately affects formula-fed premature infants and has been associated with toxins produced by Clostridium species.
ANSWER: necrotizing enterocolitis [accept NEC; prompt on colitis or enterocolitis]
<AY, Biology>