Do You Know What Thyroxine Does in the Human Body?

Thyroxine is one of the main hormones secreted by thyroid follicular cells. What is the role of thyroxine in the human body? Let's take a look at it.

1. The formation of thyroxine

The formation of thyroxine goes through six processes: synthesis, storage, iodization, reabsorption, decomposition and release.

(1) Follicular epithelial cells take amino acids from the blood, synthesize the precursor of thyroglobulin in the rough endoplasmic reticulum, and then add sugar in the Golgi complex and concentrate to form secretory particles, which are then discharged into the follicular cavity by exocytosis for storage.

(2) Follicular epithelial cells can take up I- from the blood, and I- is activated by the action of peroxidase.

(3) Activated I- enters the follicular cavity and binds to thyroglobulin to form iodized thyroglobulin.

(4) Under the action of thyroid stimulating hormone secreted by adenohypophysis, follicular epithelial cells achieve the endocytosis of the iodized thyroglobulin in the follicular cavity and become glial vesicles.

(5) Glial vesicles fuse with lysosomes, and thyroglobulin iodide is decomposed by hydrolytic enzymes to form a small amount of triiodothyronine (T3) and a large amount of tetriodothyronine (T4), namely thyroxine.

(6) T3 and T4 are released into the blood at the base of the cell.

2. The role of thyroxine

Thyroxine affects metabolism and protein synthesis in the body. It is important for human growth and development because of its role in controlling bone growth and neuron maturation. This hormone also increases the effects of catecholamines, and there are a number of health problems linked to high and low thyroxine levels in the body.

Thyroxine is also called T4 because its molecular structure is made up of four iodine molecules called thyroxine molecules. This hormone is synthesized in the thyroid gland and released into the blood through thyroid follicular cells. About 80% of T4 is produced in follicular cells.

In the human body, thyroxine is transported into cells through the blood. Only free or unbound hormones are transmitted into cells and considered active. Ninety-nine percent of thyroxine binds proteins in the blood. The concentration of free T4 in the blood is extremely important for medical examination and diagnosis.

This particular hormone affects metabolism by regulating how much oxygen cells use and regulating body temperature. In the liver, T4 directly affects cell regeneration, a process that converts glucose and oxygen into energy and carbon dioxide. The first step in the metabolism of thyroxine is from glucose to pyruvate. In the stomach and intestines, T4 promotes muscle contraction and digestive fluid secretion.

Thyroxine is responsible for regulating body growth and development when we are young. This hormone regulates bone growth, as well as heart and skeletal muscle development. In the skin, T4 is responsible for hair growth. As a person matures, this hormone leads to milk production and the ability to conceive. T4 is also responsible for the normal development of nerves and neurons in the body during development.

The effects of catecholamines involve the body's response to stress and the invocation of the body's defense response. These are responses to epinephrine and norepinephrine in the body. The presence of thyroxine increases the body's sensitivity to catecholamine compounds.

An underactive or overactive thyroid can cause problems with the hormone thyroxine in the body. An underactive thyroid will present as hypothyroidism and an overactive hypothyroidism will present as hyperthyroidism.