Kelenjar Tiroid 1 : Pembentukan Hormon Tiroid

Summary

This video explains the process of thyroid hormone formation from a histological perspective. It covers the structure of the thyroid gland, highlighting the follicular cells that produce T3 and T4 hormones and the C cells that produce calcitonin. The video also delves into the role of colloid as a temporary storage site and precursor for thyroid hormones, the enzymatic conversion of iodide, and the synthesis of hormones by attaching iodine to the amino acid tyrosine. Finally, it discusses how the hormones T3 and T4 are released into the bloodstream after processing within the follicular cells.

Takeaways

• 😀 The thyroid gland consists of follicular cells that surround a colloid, and between these follicular cells are parafollicular cells (C cells) that produce calcitonin.
• 😀 Follicular cells are responsible for producing thyroid hormones T3 and T4, while C cells produce calcitonin.
• 😀 The colloid in the thyroid is a temporary storage area and contains the main substance for thyroid hormone production.
• 😀 The key component in the colloid is thyroglobulin, which is essential for synthesizing thyroid hormones.
• 😀 The process of thyroid hormone formation begins with the synthesis of thyroglobulin by the endoplasmic reticulum and Golgi apparatus in follicular cells.
• 😀 Tyrosine, an amino acid, is present in large quantities within thyroglobulin and plays a crucial role in thyroid hormone synthesis.
• 😀 Iodide from the bloodstream is taken into the follicular cells and converted to an inactive iodide by the enzyme thyroid peroxidase.
• 😀 The iodide is then transported to the colloid where it is activated and attached to tyrosine molecules.
• 😀 Mono-iodotyrosine (MIT) is formed when one iodide attaches to tyrosine, while di-iodotyrosine (DIT) is formed when two iodides attach.
• 😀 The combination of MIT and DIT forms T3 (triiodothyronine), while DIT and DIT combine to form T4 (thyroxine).
• 😀 Once the thyroid hormones T3 and T4 are formed, thyroglobulin is broken down by lysosomes in the follicular cells, releasing T3 and T4 into the bloodstream.

Q & A

What is the primary function of the thyroid gland?

The primary function of the thyroid gland is to produce thyroid hormones (T3 and T4), which regulate metabolism, growth, and energy production in the body.

What are the key components of the thyroid gland's structure?

The thyroid gland is primarily composed of follicular cells, colloid, and C cells (parafollicular cells). Follicular cells surround the colloid, and C cells are found between the follicles.

What is the role of C cells in the thyroid gland?

C cells, or parafollicular cells, are responsible for producing calcitonin, a hormone that regulates calcium levels in the blood.

How are thyroid hormones (T3 and T4) synthesized?

Thyroid hormones are synthesized by the follicular cells of the thyroid gland. Iodine from the bloodstream is converted to iodide within the cells, where it is attached to the amino acid tyrosine in thyroglobulin to form MIT (mono-iodotyrosine) and DIT (di-iodotyrosine), which combine to form T3 and T4.

What is the role of the colloid in thyroid hormone synthesis?

The colloid serves as the storage site for thyroglobulin, the precursor of thyroid hormones. It temporarily holds the iodinated thyroglobulin before the hormones are released into the bloodstream.

What is the process by which iodide is converted to an active form in the thyroid gland?

Iodide from the bloodstream is absorbed into the follicular cells, where it is converted into iodine by the enzyme thyroid peroxidase. This active iodine is then attached to tyrosine residues in thyroglobulin.

What happens when MIT and DIT combine?

When MIT (mono-iodotyrosine) and DIT (di-iodotyrosine) combine, they form T3 (triiodothyronine) and T4 (thyroxine), the active thyroid hormones.

What happens to thyroglobulin during the release of T3 and T4 into the bloodstream?

When T3 and T4 need to be released into the bloodstream, thyroglobulin is broken down inside the follicular cells by lysosomes. This breakdown results in the release of the active thyroid hormones, T3 and T4.

What is the difference between T3 and T4?

The difference between T3 and T4 lies in the number of iodine atoms attached to the tyrosine molecule. T3 (triiodothyronine) has three iodine atoms, while T4 (thyroxine) has four. T3 is the more active form, while T4 serves as a precursor that is converted to T3 in peripheral tissues.

How does the thyroid hormone synthesis process contribute to the regulation of metabolism?

Thyroid hormones (T3 and T4) regulate metabolism by controlling the rate of energy production in cells, affecting growth and development, and maintaining body temperature. They ensure that cells have the right amount of energy to carry out essential functions.