Thyroid Gland Histology Flashcards
What is the embryological origin of the thyroid gland?
Endoderm downgrowth between pouches I and II
What are C-cells from?
Neural crest cells
What do C cells make?
Calcitonin
What do follicular cells synthesize?
Thyroid hormones
What activates follicular cells?
TSH
What do inactive follicular cells look like?
cuboidal/squamous
Few mitochondria, small golgi, some RER
What do activated follicular cells look like?
Columnar Many mitochondria, enlarged golgi Increased RER Colloid absorbed Apical lysosomes
C cells are also known as…
Parafollicular cells
What does calcitonin do?
LOWERS calcium in blood by inhibiting bone resorption
Decreases osteoclasts
Promoting clacium and phosphate excretion
What protein makes up colloid in the thyroid gland?
Thyroglobulin
What oxidizes iodide in the colloid?
Thyroid peroxidase
What gets iodinated in colloid?
Tyrosyl residues
What protein on the colloid surface transports iodide? Blood surface?
Colloid: Pendrin
Blood: Na/I symporter
How is thyroglobulin taken up?
Pinocytosis
Where is thyroglobulin proteolyzed?
In lysosomes
