Thyroid Flashcards
Thyroid tissues consist of
Sac like structures called thyroid follicles
How are the follicular cells arranged
In circular pattern
Characteristics of the follicle cells (2)
Single layer of epithelium
Synthesize the thyroid hormone
Follicles are filled with what
Colloid
What is the colloid (2)
Viscous protein rich liquid
Main storage form of the thyroid hormone
C cells or parafollicular cells are located where
outside follicle
C cell secrete
Calcitonin
Calcitonin is
A hormone that regulate calcium metabolism
Molecules important for the production of thyroid hormones (2)
Tyrosine
Iodine
Tyrosine is a part of a large protein called
Thyroglobulin
Where does iodine come from
From the diet
Iodine is converted to
Where
Iodide
In the intestinal tract and transported to thyroid
T or F
Iodide concentration is higher in the outside of the cell
False
Concentration is 25-200x higher IC
How do follicle cell trap iodide
With the Na/I transporter
The 1st step in the production is
Oxidation of iodide into iodine
Who oxidizes iodide into iodine
Thyroid peroxidase (TPO) located in the apical membrane
Binding of the iodine with the thyroglobulin molecule is called
And happens where
Organification of the thyroglobulin
In colloid or outside of cell
Tyrosyl ring can accommodate 2 iodine molecules which are
MIT monoiodotyrosine
DIT diiodotyrosine
MIT is
One molecule of iodine
DIT is
Two molecules of iodine
TPO catalyzes the fusion of
2 of these iodinated tyrosines
1 DIT + 1DIT=
4 iodine molecules
1MIT + 1 DIT=
3 iodine molecules
3 iodine-tyrosine molecules are called
T3 OR TRIIODOTHYRONINE
4 iodine-tyrosine molecules are called
T4 OR THYROXINE
What is the major hormone produced by follicle cells
T4
Thyroid hormones will secreted after stimulation by
TSH
TSH is released by
Adenohypophysis
Who releases TRH
Hypothalamus
How are thyroid hormones are transported
In plasma attached proteins such as Thyroxine binding protein (TBG) and albumin
TGB and albumin are produced by
Liver
Free T4 enters and is converted into T3 by
Iodothyronine deiodinases in cytosol
What is the primary factor for the control of metabolism
Thyroid hormones
Actions of thyroid hormones (7)
Increase the number of mitochondrial prot and activity Increase basal metabolic rate of cells Stimulate carbohydrate metabolism Fat metabolism Influence growth and development Increase blood flow and cardiac output Increase heart rate
T or F
Weight gain in hypo
Weight loss in hyper
True
T or F
Plasma and liver fat are decreased under thyroid stimulation
True
