From ehealthMD's page on hypothyroidism:
Most symptoms, such as lower heart rate, tiredness, poor memory or difficulty in thinking, even constipation, are due to inadequate stimulation of the various organs in the body due to insufficient amounts of thyroid hormone.
Is the definite article necessary here? Could we omit it? After all, these are not some specific, previously mentioned organs:
Most symptoms, such as lower heart rate, tiredness, poor memory or difficulty in thinking, even constipation, are due to inadequate stimulation of various organs in the body due to insufficient amounts of thyroid hormone.
Or maybe the is used to indicate "the organs that are functioning poorly in hypothyroidism"? Or is "the various organs in the body" a large generic noun phrase?
The authors of the article are native speakers of English, judging by their names and positions.