Thyroid system

In the HPT axis, where are thyrotrophes that secret TSH located?

Thyroid gland

Hypothalamus

Anterior pituitary

The thyroid hormone system stimulates cellular respiration, oxygen consumption, lipid and carbohydrate metabolism and metabolic rates in various parts of the body. What is the byproduct of this?

Raise in body tempurature

Decrease in body tempurature

Increase in energy

Decrease in energy

What are functions of the thyroid hormone system?

Metabolism

Development and growth

Protein synthesis

All of the above

Which is the only endocrine organ that stores its product extracellularly?

Thyroid gland

Pituitary gland

Adrenal gland

None of the above

What contains thyroglobulin with inactive form of thyroid hormones?

Follicle

Colloid

Isthmus

All of the above

Which cells in the thyroid gland secrete thyroid hormones?

Follicle cells

Parafollicular cells

Isthmus cells

All of the above

Which cells are important for the removal of calcium from the blood? (no direct contact with lumen)

Follicle cells

Parafollicular cells

Calcitonin releasing cell

F M L cell

What are the functions of thyroid peroxidase?

How many molecules of iodotyrosines are required to form thyroxine or triiodothyronine?

How are thyroid hormones released?

By follicle cells

By parafollicular cells

Colloid endocytosis

Type-1 deiodinase (D1) converting T4 to T3 allowing passage from the basal surface of the cell into the blood

T3/T4 are poorly soluble when unbound, as more than 99% are bound to a carrier protein such as:

Thyroxine binding globulins

Transthyretin

Albumin

All of the above

What do thyroid hormone receptors bind in the absence of the hormone?

T3 response elements

T4 response elements

RNA

What form of TH receptors have the highest affinity binding for TREs? (contains RXR)

Monomer

Homodimer

Heterodimer

None of the above

Common causes of hypothyroidism are:

Iodine deficiency

Hashimotos disease

Accumulation of colloids

All of the above

What does graves disease do?

Antibodies bind and activate TSH receptor leading to continual TH synthesis

Interferes with iodination of thyroglobulin

Cause hyperthyroidism

Cause hypothyroidism

TH in non mammalian vertebrates can help with amphibian metamorphosis and salmon smoltification

True

False

Thyroid system

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