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Flashcards in Thyroid Function Deck (22):

Why is the Thyroid Gland brown?

Becuase of the obsorbed iodine


What is the name of the ajoing part between the two lobes of the thyroid?



What are the bumps on the Thyroid?

The bumps are called lobules abd contain follicles which is where the hormone is made


What is the order of organisation of the thyroid gland?

Lobules - Tyroid Follicles - collid and follicular cells and C-Cells


What do you find within the Collid and what does it do?

Thyroglobulin molecules, that carry the T3 and T4


What is a free T3 and T4?

These are hormones that have been released by the Throid globuline molecule. These are now active.


What are the basic ingredients of Throid Hormones?

Tyrosine and Iodine


How is T4 and T3 made?

T4 = 2 x DIT molecules
T3 = 1 x MIT and 1 x DIT


What is the differences between T3 and T4?

T4 is the primary molecule but is usless, it need to be reduced to T3 so that it can complete its role


There are 3 globulines that T3 and T4 bind to, what are there names?

TBG = Thyroid Binding Globuline
TBPA = Thyroid Binding Pre Albumine
TBA = Thyroid Binding Albumine


Explaine how steriod work?

Steroids are lipid soluable so slide through the membrane.
Then bind to receptors in the cytoplasm.
The get carried into cell to act on DNA


Explaine the two ways Thyrodi hormones work?

They bind to a receptor in the cytoplasm and get carried to the DNA (just like a steroid) or they bind to the mitrocondria and make ATP. So can effect the genome (pathway 1) or no genome effect (pathway 2)


How does Adrenaline and noradrenaline work?

They use sencond messangers. Bind onto external receptors on the membrane, which activates the G - Protein linked receptor. This second receptor then leaves and causes the cell response.


List some of the actions caused by increased T3 and T4.

Increased oxygen consumption
increased cardiac output
Increase Basal Metabolic Rate
Increase ATP


What effect does T3 and T4 have physically on the body systems?

Increased HR and Systolic and Diastolic BP, increased blood flow
Increase of ventalation rate
Increase appitites, increase digestive juice


What is the pathway between the hypothalamus and the target response?

Hypothalamus releases Thyroid releasing hormone (TRH) which goes to the Anterior pituitory via portal system. It releases Thyroid Stimulating Hormone (TSH), which travels to the Thyroid gland. It releases T3 and T4 and BMR is increased, protein synthesis is increased etc etc


What effect does the TSH hormone, released by the pituitory gland, have on the Thyroid Gland?

Increase of Iodine absorbtion
Stimulates T3 and T4 creation
Increase in thyroglobulin secreation into colloid
Increase in colloid endocytosis
Increase in follicular cells
Increase of blood flow


What is hyper and hypo thyrodisum?

Over production and underproduction of Thyroid homones.
Primary - problem at Throid gland
Secondary - problem at Pituitory gland
Tertiary - problem at the hypothalamus


Explaine Hypothyroidisum?

This is when the Thyroid dosent produce enough T3 and T4. Causes an increase level of TSH and reduced negative feedback from Tyroid gland, defincency in iodine (Goiter)


What are the common effects of Hyperthyroidisum?

Increased BMR
Weight loss, appitites increase
Anxity, mental excitability
Hair loss
Increased heart rate
Graves disease (toxicity of T3 and T4)


What are the common effects of Hypothyroidsium?

weight gain
Dry skin, brittle hair
Dry cold skin


Are thyroid hormones lipophydic?

Yes - fat loving water hating. as are steroids.