THYROID GLAND Flashcards
PART 2
- Butterfly shaped gland
- Consists of two lobes in the lower neck below the voice box
Thyroid Gland
It connects the lobe via a NARROW BAND
Isthmus
- A fundamental structural unit of the thyroid glans
- It is where the synthesis and storage of the thyroid hormones
Follicle
- A glycoprotein with positive “ Periodic Acid Schiff” staining
- It acts as a performed matric containing tyrosyl groups
- It is stored in the follicular colloid of the thyroid gland
Thyroglobulin
- 2 types of cells in Thyroid gland
Follicle (T3 and T4) and Parafollicular/ C- cells (Calcitonin)
It is a neuroendocrine system that regulates the production and secretion of thyroid hormes
Hypothalamic-pituitary-thyroid axis (HPTA)
It stimulates the synthesis of thyroid hormones through cellular uptake of dietary iodine
Thyroid-Stimulating Hormone
- It is a glycoprotein secreted by the follicles specially in the RER
- It is rich in Tyrosine
- It is where the integration if iodine and tyrosyl residue occurs
It is the prohormone of thyroid hormone
Thyroglobulin
- It catalyzes the iodination of tyrosyl residue in thyroglobulin
- It is also involved in the coupling of MIT and DIT
Thyroid Peroxidase
- the products of the iodination of tyrosyl residue
Monoioidotyrosine (MIT)
Diiodootyrosine (DIT)
- It is the prehormone of T3
T4
- It is produced in the cytoplasm from the removal of one iodide outer ring of T4
T3
- 2 organ involved in the conversion of T4 to T3
Liver and Kidney
Hormones that are both released in the blood circulation from the thyroid cells
T4 and T3
- it the sources for the formation of free thyroid hormones
Protein-bound thyroid hormones
- It is formed from the removal of one of the iodide inner rings of T4
Reverse T3 (rT3)
- it is a biologically inactive metabolite of T4 and is bound to thyroxine-binding globulin
Reverse T3 (rT3)
- it catalysis the deiodination of T4 producing T3 and rT3
Type 1 iodothyronine 5’ deiodinase
- it maintain the constant level or T3 in the CNS
Type 2 iodothyronine 5’deiodinase
- It is metabolically inactive
Protein bound hormones
- They are physiologically active portion of the thyroid hormones
FT4 and FT3
- they do not enter cells
- they are biologically inert
- they function as storage sites for the circulating thyroid hormones
Protein Bound Thyroid Hormone
- It is the most important element in the biosynthesis of thyroid hormones
Iodine
If the iodine intake is diminishes
MIT produced greater quantities leading to increased T3 formation and released
Iodine intake per day and an indication of deficiency in hormone secretion
Below 50ug
- It is synthesized in the parafollicular cells from the CLEAVAGE and post-translational modification of pre-calcitonin the procalcitonin
Thyrocalcitonin
- It maintains the balance of CALCIUM and PHOSPORUS in the plasma
Thyrocalcitonin
- It is the POTENT CALCITONIN SECRETAGOGUES of CALCIUM and PENTAGASTRIN
Thyrocalcitonin
- It is a protein that RESPONSE to SYSTEMIC inflammatory condition
Procalcitonin
- It is a marker for BACTERIAL SEPSIS and is now part of the PANEL TEST for COVID-19
Procalcitonin
- It is a 116 amino acid and is discovered as a PROHORMONE of CALCITONIN
- The sample is SERUM
- Reference range
Male: 1 - 20 ng/mL
Female: 1 - 25 ng/mL
Procalcitonin
Function of Thyroid Hormone (T3 and T4)
- Tissue Growth
- Mental Development
- Development of CNS
- Heat Production
- Control of oxygen consumption
- Influence carbohydrate and protein metabolism
- Energy consumption
