Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones.
A singular subject is a noun or a pronoun for just one person, place, or thing. A plural subject is a noun or a pronoun that is two or more persons, places, or things. Exampl â¦ es: Singular subject: The boy came for lunch. He was hungry. Plural subject: The boys came for lunch.
Definition of subject for Students. 1  1 : the person or thing discussed : topic She's the subject of rumors. 2  2 : an area of knowledge that is studied in school Geography is my favorite subject. 3  3 : a person who owes loyalty to a monarch or state.  4 : a person under the authority or control of another.