19.1 Thyroid gland Flashcards
What are the 4 peripheral endocrine glands
Thyroid gland, Adrenal glands, Parathyroid glands, and endocrine pancreas
discuss the structure and location of the thyroid gland
consists of two lobes of endocrine tissue
joined in the middle by a narrow portion of the gland, the isthmus, giving it a bow-tie shape (alternatively described as a butterfly shape) . The gland is located in the neck over the trachea just below the larynx
What is the name of the thyroid cells that secrete thyroid hormones and are organised into colloid-filled follicles
follicular cells
Each follicle is a hollow sphere of follicle cells surrounding the colloid, where ________ stores thyroid hormones during synthesis
Thyroglobulin (Tg)
What is Thyroglobulin
It is a large glycoprotein that stores thyroid hormoness during synthesis
What are the two thyroid hormones
Thyroxine/ tretriodothyronine (T4) and tri-iodothyronine (T3)
The two thyroid hormones are derived from?
iodine and tyrosine
What is the function of thyroid hormones?
To regulate the body’s basal metabolic rate
Where is iodine obtained since the body cannot synthesis it?
from diet
How is iodine transported into follicular cells?
Through the iodine trap, where iodine is oxidised and attached to tyrosine within thyroglobulin
The process of iodine getting transported into the follicular cells forms?
Monoiodotyrosine (MIT) and diiodotyrosine (DIT), which then couple to form T3 (MIT + DIT) and T4 (DIT + DIT)
Where do the synthesised thyroid hormones remain stored until they are needed?
In the colloid
Where are C cells located and what is their function
They are located between the follicles and they secrete calcitonin
What does calcitonin do?
It is a hormone involved in calcium metabolism (not related to T3 and T4)
Where are thyroid hormones synthesised
On thyroglobulin
The supply of thyroid hormones allows the body to meet its metabolic needs for how long
several months
What are the 6 effects of thyroid hormone
- control the body’s basal metabolic rate
- Influence synthesis and degradation of carbohydrate, fat and protein
- Increases target-cell responsiveness to catecholamines
- Increased heart rate and force of contraction
- Essential for normal growth
- Plays a crucial role in the normal development of the nervous system
Thyroid hormone binds to which receptor
a nuclear receptor bound to the thyroid-response element of DNA
