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Questions and Answers

Where is the thyroid gland located?

Just below the larynx (correct)

Near the pancreas

Above the larynx

Next to the heart

What is the function of parafollicular cells in the thyroid gland?

To secrete calcitonin and regulate blood calcium levels (correct)

To regulate thyroid-stimulating hormone (TSH)

To produce thyrotropin-releasing hormone (TRH)

To secrete T3 and T4

What is the role of thyrotropin-releasing hormone (TRH)?

To stimulate the production of TSH (correct)

To regulate thyroid gland location

To regulate blood calcium levels

To secrete T3 and T4

What is the role of TSH?

To stimulate the production of T3 and T4 Signup and view all the answers

What is a characteristic of follicular cells in the thyroid gland?

They secrete T3 and T4 Signup and view all the answers

What is essential for the production of thyroid hormones?

Iodine Signup and view all the answers

What is the function of the pituitary gland in relation to the thyroid gland?

To secrete TSH Signup and view all the answers

What is the hierarchy of regulation of thyroid hormone production?

TRH > TSH > Thyroid gland Signup and view all the answers

What is the result of the reaction between iodine and tyrosine in the thyroid gland?

Formation of T3 and T4 Signup and view all the answers

What is the function of thyroid hormones in regulating metabolism?

Regulating protein synthesis Signup and view all the answers

What is the effect of thyroid hormones on the sensitivity of tissues to catecholamines?

They increase the sensitivity Signup and view all the answers

What is the difference between T3 and T4 in terms of half-life?

T3 has a half-life of 1 day, while T4 has a half-life of 1 week Signup and view all the answers

What is the term for a patient with a normal functioning thyroid gland?

Euothyroid Signup and view all the answers

What is the main cause of endemic goitre?

Low iodine intake Signup and view all the answers

What is the term for the enlargement of the thyroid gland?

Goitre Signup and view all the answers

What is the effect of goitre on the airway?

It endangers the airway Signup and view all the answers

What is the definition of goitre?

An enlarged thyroid gland due to lack of iodine Signup and view all the answers

What is the term for the syndrome of hyperthyroidism, exophthalmos, and enlargement of the thyroid gland?

Graves' disease Signup and view all the answers

Study Notes

Anatomy and Physiology of the Thyroid Gland

The thyroid gland is located just below the larynx.
Follicular cells secrete T3 and T4, which are assembled in colloid.
Parafollicular cells secrete calcitonin, which regulates blood calcium levels by decreasing blood levels of calcium ions.

Regulation of Thyroid Hormones

TSH (thyrotropin) from the pituitary gland regulates thyroid hormone secretion.
TSH is regulated by thyrotropin-releasing hormone (TRH) from the hypothalamus.
Iodine from the blood is converted to iodide, which is then used to produce T3 and T4.

Thyroid Hormones

Thyroxine (T4) has a half-life of 1 week.
T4 is converted to tri-iodothyronine (T3), the active form, which has a half-life of 1 day.
Thyroid hormones are stored as iodide-rich 'thyroid colloid'.

Functions of Thyroid Hormones

Thyroid hormones act on metabolism by regulating protein synthesis.
Thyroid hormones have profound effects on the sensitivity of tissues to catecholamines.
Thyroid hormones have roles in growth and development.

Types of Patients

Euothyroid: patients with normal thyroid function.
Hyperthyroid: patients with an overactive thyroid gland.
Hypothyroid: patients with an underactive thyroid gland.

Goitre

Enlargement of the thyroid gland.
Causes of goitre include:
- Physiological enlargement (e.g., during pregnancy).
- Low iodine intake or natural goitrogens.
- Drugs (e.g., thiouracil, carbimazole).
- Thyroid disease (e.g., Graves' disease).
- Thyroiditis.
- Carcinoma.
- Cretinism.
Goitre can endanger the airway.
Goitre can be due to lack of iodine.

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