thyroxine
(noun)
A thyroid hormone also known as T4, thought to be a pro-hormone and a reservoir for T3.
Examples of thyroxine in the following topics:
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Development of the Endocrine System
- It is involved in the production of the hormones T3 (triiodothyronine) and T4 (thyroxine).
- The normal thyroid gland may store several weeks supply of thyroxine in this bound form.
- Thyroxine is also necessary for normal growth.
- If there is an insufficient amount of thyroxine, a condition referred to as hypothyroidism results.
- Sometimes, the thyroid gland produces too much thyroxine, a condition known as hyperthyroidism.
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Control of Thyroid Hormone Release
- The production of thyroxine and triiodothyronine is regulated by thyroid-stimulating hormone (TSH) that is released from the anterior pituitary.
- The production of thyroxine (T4) and triiodothyronine (T3) is primarily regulated by thyroid-stimulating hormone (TSH) that is released from the anterior pituitary gland.
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Control of Hormone Secretion
- A key example of a negative feedback system is the regulation of the thyroid hormone thyroxine, which regulates numerous key metabolic processes.
- The thyroid-stimulating hormone then stimulates the release of thyroxine from the thyroid gland.
- When the blood concentration of thyroxine rises above the ideal value as detected by sensory neurons, the hypothalamus is signaled to stop thyroid-releasing hormone production, which eventually lowers the levels of thyroxine in the blood.
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Action of Thyroid Hormones
- The primary function of the thyroid is to produce the hormones triiodothyronine (T3), thyroxine (T4), and calcitonin.
- Triiodothyronine (T3) and thyroxine (T4) are enzymes produced by the thyroid gland.
- In the blood, T4 and T3 are partially bound to thyroxine-binding globulin (TBG), transthyretin, and albumin.
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Formation, Storage, and Release of Thyroid Hormones
- The thyroid hormones thyroxine (T4) and triiodothyronine (T3) are produced from thyroid follicular cells within the thyroid gland, a process regulated by the thyroid-stimulating hormone secreted by the anterior pituitary gland.
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Overview of the Thyroid Gland
- It participates in these processes by producing thyroid hormones, the principal ones being triiodothyronine (T3) and thyroxine (sometimes referred to as tetraiodothyronine (T4)).
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Pituitary Gland Disorders
- Once the effector glands produce sufficient hormones (thyroxine, cortisol, estradiol or testosterone and IGF-1), both the hypothalamus and the pituitary cells sense their abundance and reduce their secretion of stimulating hormones.
- Thyroid-stimulating hormone (TSH) deficiency leads to hypothyroidism (lack of production of thyroxine (T4) and triiodothyronine (T3) in the thyroid).
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Overview of Endocrine Glands
- It is involved in the production of the hormones T3 (triiodothyronine) and T4 (thyroxine).