Question

Following hormones are iodothyronines (a) T3 (b) T4 (c) \(\mathrm{TCT}\) (d) Both (a) and (b)

Short answer

The correct answer is (d): Both (a) and (b) are iodothyronines.

Step-by-step solution

Identify iodothyronine hormones

To get the answer, first identify what iodothyronine hormones are. They are hormones produced by the thyroid gland that contain iodine. The two most significant of these are T3 (triiodothyronine) and T4 (thyroxine).

Match the hormone with the list

After identifying what iodothyronine hormones are, the next step is to match these hormones with the ones on the list. Both T3 and T4 are present, but TCT is not an iodothyronine.

Select the correct choice

From the matching done in the previous step, the only fitting option that includes both correct hormones, T3 and T4, is option (d): Both (a) and (b).

Key concepts

Thyroid Hormones

The thyroid hormones play a crucial role in regulating various physiological processes in the body. They are essential for maintaining the body's metabolism, the rate at which the body uses energy. Produced by the thyroid gland, these hormones influence the development and functioning of several systems, including the nervous and cardiovascular systems.

Thyroid hormones primarily consist of two important iodothyronines: triiodothyronine (T3) and thyroxine (T4). These hormones contain iodine atoms, which are vital for their biological activity. Importantly, the thyroid gland relies on iodine intake from the diet to synthesize these hormones.

• Regulate metabolism and energy use
• Influence growth and development
• Vital for proper neurological function

Overall, thyroid hormones are integral to the body's ability to function efficiently, normalize energy levels, and ensure balanced growth and development.

Triiodothyronine (T3)

Triiodothyronine, commonly known as T3, is one of the primary hormones produced by the thyroid gland. It is much more potent than its counterpart T4, although it is present in smaller amounts. T3 acts quickly and has a significant impact on numerous physiological functions.

T3 contains three iodine atoms, and it influences how the body's cells use energy. It plays a major role in metabolic processes, regulating heart rate and body temperature, as well as influencing muscle strength and protein synthesis.

• More potent than T4
• Contains three iodine atoms
• Regulates metabolism and energy expenditure

In the endocrine system, T3 is essential for converting into its active form to exert its effects, playing a part in ensuring rapid and efficient physiological responses.

Thyroxine (T4)

Thyroxine, also referred to as T4, is another key hormone produced by the thyroid gland. Unlike T3, T4 circulates in higher amounts in the bloodstream and serves primarily as a precursor to T3. This means it gets converted into T3 as the body requires.

Containing four iodine atoms, T4 is less potent but more abundant, making it crucial in maintaining consistent metabolic rates over time. It aids in regulating cholesterol levels, influencing body weight, and supporting cognitive function.

• Contains four iodine atoms
• Less potent but more abundant than T3
• Serves as a precursor to T3

In the context of endocrinology, T4's stable nature provides a reservoir for conversion to the more active T3, ensuring ongoing regulation of vital bodily functions.

Endocrinology

Endocrinology is the branch of biology and medicine that deals with hormones, the glands that produce them, and their related disorders. It encompasses the study of how hormones influence the body's various functions and how imbalances can lead to medical conditions.

The thyroid gland is a significant focus within endocrinology due to its critical role in hormone production and regulation. Disorders like hyperthyroidism or hypothyroidism arise from an overproduction or underproduction of thyroid hormones, respectively.

• Study of glands and hormones
• Focus on hormonal imbalances and associated health issues
• Involves diagnosis and treatment of endocrine disorders

Overall, understanding endocrinology is essential for recognizing how hormones like T3 and T4 affect both everyday bodily functions and potential disorders, guiding effective treatment and management.