Structure:
The thyroid gland is the two-lobed organ in the neck, in front of the trachea,
below the larynx. A tissue bridge called the thyroid isthmus, connects
the lobes. The follicular cells of the gland secrete thyroxine and the
parafollicular cells secrete calcitonin.
Function:
The thyroid gland secretes thyroxine into
the circulation after stimulation by TSH
from the hypophysis, and calcitonin
in response to elevated levels of Ca++ in the blood.
