Thyroid Structure and Hormone Regulation

Questions and Answers

What is the primary function of the thyroid gland?

Filtering blood

Regulating thyroid hormone production (correct)

Regulating blood pressure

Producing insulin

Thyroid hormones T3 and T4 are hydrophilic molecules.

False

What amino acid are thyroid hormones derived from?

tyrosine

The thyroid gland regulates the production of thyroid hormones via __________ secretion.

TSH Signup and view all the answers

Match the following components of the thyroid gland with their characteristics:

Thyroid follicles = Sac-like structures Thyroid hormones = Bind to nuclear receptors T3 and T4 = Derived from tyrosine Follicular cells = Arranged in circular patterns Signup and view all the answers

What substance is the main storage site for thyroid hormones?

Colloid Signup and view all the answers

Thyroid hormone synthesis involves the active transport of iodine into the follicle cells.

True Signup and view all the answers

What hormone do parafollicular cells secrete to decrease plasma calcium levels?

calcitonin Signup and view all the answers

The active form of thyroid hormone produced from thyroglobulin is __________.

thyroxine Signup and view all the answers

Match the following components of the thyroid gland with their functions:

Follicular cells = Synthesize and secrete thyroglobulin Parafollicular cells = Secrete calcitonin Thyroid hormones = Increase metabolic rate Iodine transport = Active transport into thyroid follicles Signup and view all the answers

Study Notes

Thyroid Tissue Structure

Composed of numerous sac-like structures known as thyroid follicles.
Thyroid follicles vary in size and play a crucial role in hormone production.
Follicular cells are organized in a circular arrangement within the follicles.

Regulation of Hormones

The thyroid gland controls the production of thyroid hormones through the secretion of Thyroid Stimulating Hormone (TSH).
TSH plays a significant role in stimulating the activity of follicular cells.

Thyroid Hormones

Thyroid hormones, specifically T3 (triiodothyronine) and T4 (thyroxine), are produced from the amino acid tyrosine.
Both T3 and T4 are hydrophobic, allowing them to easily pass through cell membranes.
Thyroid hormones exert their effects by binding to nuclear receptors, influencing gene expression and metabolic activity.

Thyroid Follicles and Hormone Storage

Thyroid follicles are filled with colloid, serving as the primary storage site for thyroid hormones.
Colloid contains thyroglobulin, a protein component that includes the amino acid tyrosine.

Thyroid Hormone Synthesis

Thyroglobulin is synthesized within follicular cells and secreted into colloid for hormone production.
Iodine is absorbed from the diet by follicular cells and actively transported into thyroid follicle cells.
Iodide is trapped within these follicular cells through active transport mechanisms.
The conversion of colloid to active thyroxine occurs within follicular cells, leading to increased metabolic rate, thermogenesis, and gluconeogenesis.

Parafollicular Cells (C-cells)

Parafollicular cells are located outside thyroid follicles, are large, pale, and round in appearance.
They secrete calcitonin in response to elevated plasma calcium levels.
Calcitonin functions to reduce blood calcium levels by decreasing osteoclast activity and increasing renal calcium excretion.

Description

Explore the intricate structure of thyroid tissue, including the essential thyroid follicles and their role in hormone production. Learn about the regulation of thyroid hormones, including T3 and T4, and their impact on metabolic activity.