respiratory center vs medulla

respiratory center and medulla both are nouns.

Word	Noun	Adjective	Verb	Adverb
respiratory center	Yes	No	No	No
medulla	Yes	No	No	No

respiratory center (noun)	medulla (noun)
the center in the medulla oblongata and pons that integrates sensory information about the level of oxygen and carbon dioxide in the blood and determines the signals to be sent to the respiratory muscles	the inner part of an organ or structure in plant or animal
	lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata)
	a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers