physiology vs voluntary

physiology and voluntary both are nouns.

Word	Noun	Adjective	Verb	Adverb
physiology	Yes	No	No	No
voluntary	Yes	Yes	No	No

physiology (noun)	voluntary (noun)
processes and functions of an organism	composition (often improvised) for a solo instrument (especially solo organ) and not a regular part of a religious service or musical performance
the branch of the biological sciences dealing with the functioning of organisms	(military) a person who freely enlists for service

physiology (adjective)	voluntary (adjective)
	of your own free will or design; done by choice; not forced or compelled
	controlled by individual volition