Thyroid Physiology Flashcards
Anatomical Location of thyroid
C5-T1
Innervation
Parasympathetic = vagus Sympathetic = sympathetic trunk
Blood supply
Superior and inferior thyroid arteries
Which arteries gives off superior and inferior thyroid arteries?
External carotid
Venous drainage
superior, middle and inferior thyroid veins
Where do the thyroid veins drain into?
Superior = internal jugular vein Middle = internal jugular vein Inferior = brachiocephalic vein
What hormone raised blood calcium?
Parathyroid
What hormone decreases blood calcium?
calcitonin
What is a thyroglobulin?
big long chain with lots of tyrosine residues attached
How is iodine involved in hormone synthesis?
iodine enters follicular cell alongside Na
iodine leaves follicular cell and goes into colloid
iodine is attached to tyrosine residues on thyroglobulin
a tyrosine with 1 iodine?
monoiodotyrosine unit
a tyrosine with 2 iodine?
di-iodotyrosine unit
MIT + DIT = ?
tri-iodothyronine, T3
DIT + DIT = ?
Thyroxine, T4
What enzyme is used to add iodine groups to tyrosine residues?
Thyroid peroxidase
Name 3 plasma proteins for thyroid hormones
Thyroxine binding globulin (70%)
Thyroxine binding prealbumin
Albumin
What type of deIodinase enzyme converts T4–>T3?
type 2
What does type 3 deIodinase enzyme do?
convert T4 into inactive T3
