It is an adjustment to environmental conditions.

Astructural difference between the trachea and esophagus that prevents the trachea from collapsing is the presence of: a) smooth muscle b) skeletal muscle c) respiratory cilia d) rings of cartilage

Which of the following is not a possible cause of conduction deafness? a) cochlear nerve degeneration b) middle ear infection c) impacted cerumen d) otosclerosis

Why would one lymph node in the neck be swollen and not the other? what causes them to swell?