Thyroid Hormone Synthesis and Function Quiz

The basic building block of the thyroid gland, responsible for hormone production.

Specialized cells lining the thyroid follicle, responsible for synthesizing and releasing thyroid hormones.

The fluid inside the thyroid follicle, containing thyroid hormones in their inactive form.

Tiny blood vessels that supply the thyroid gland with nutrients and oxygen, and transport hormones to other parts of the body.

Nerves that regulate hormone production and secretion, responding to stress and other stimuli.

Structures that drain excess fluid from the thyroid gland.

Specialized cells in the thyroid gland that secrete calcitonin, a hormone that regulates calcium levels in the blood.

The process of the thyroid gland's development during fetal life.

This is a remnant of the thyroglossal duct which may persist after the duct completely obliterates. This remnant can sometimes form into a cyst.

A cyst formed from the remnants of the thyroglossal duct, usually located in the midline of the neck, just below the hyoid bone.

A condition where thyroid tissue develops in an abnormal location along the path of the thyroglossal duct.

Thyroid tissue found in the tongue.

A thyroid hormone important for regulating metabolism in the body.

A thyroid hormone important for regulating metabolism in the body.

A form of thyroid hormone that is biologically inactive.

The process of creating thyroid hormone from iodide and tyrosine residues

A hormone produced by the thyroid gland that is crucial for many bodily functions, including brain development, metabolism, and growth.

Thyroid hormone increases basal metabolic rate and oxygen consumption by stimulating the activity of the Na+-K+ ATPase pump.

A condition where the thyroid gland enlarges (forms a goiter) in response to low iodine levels in the body, leading to inadequate thyroid hormone production.

A severe form of hypothyroidism caused by iodine deficiency during pregnancy and postnatally, characterized by developmental delays, mental retardation, and physical stunting.

Iodine is a crucial micronutrient that plays a key role in the synthesis of thyroid hormone.

Thyroglobulin is a large protein produced by the thyroid gland that serves as the foundation for thyroid hormone production.

Tyrosine is an amino acid that is essential for the synthesis of thyroid hormone.

The process of thyroid hormone synthesis involves multiple steps, including iodine trapping, oxidation, coupling, endocytosis, proteolysis, and transport.

A protein found in the colloid of the thyroid follicle, it is the precursor to thyroid hormones.

A protein found in the thyroid follicular cell membrane, it actively pumps iodine from the bloodstream into follicular cells using energy from ATP. It transports iodide against its concentration gradient.

An enzyme found in the thyroid follicular cell membrane, it converts iodide (I-) to iodine (I2). It also catalyzes the iodination of tyrosine residues on thyroglobulin, the precursor to thyroid hormones.

The process of incorporating iodine into tyrosine residues on thyroglobulin. This process is catalyzed by thyroid peroxidase (TPO) and leads to the formation of MIT and DIT, the building blocks of thyroid hormones.

Thyroid hormones are fat-soluble and require carrier proteins to travel in the bloodstream. These proteins bind to thyroid hormones with varying degrees of strength.

T4 is bound more tightly to all three significant serum binding proteins: thyroxine binding globulin (TBG), thyroxine-binding prealbumin (transthyretin) (TBPA), and serum albumin.

Only a very small fraction of circulating T4 and T3 are in protein-free form. This free fraction is the biologically active form of the hormone.

T4 is the main hormone secreted by the thyroid gland. It acts as a precursor for the more potent hormone, T3.

T3 is the most active form of thyroid hormone in regulating metabolism.

Thyroid hormone (T3) binds to the thyroid response element on DNA, triggering a cascade of events leading to gene expression and protein synthesis.

Thyroid hormone stimulates carbohydrate metabolism by promoting glucose uptake, enhancing glycolysis and gluconeogenesis, and increasing insulin secretion.

Thyroid hormone promotes fat metabolism by increasing lipolysis, mobilizing lipids from adipose tissue, and leading to increased β-oxidation. It also decreases plasma cholesterol, phospholipids, and triglycerides.

Thyroid hormone increases the number of mitochondria, Na+/K+ ATPase activity, oxygen consumption, protein synthesis, and basal metabolic rate. These effects contribute to overall energy expenditure and cellular function.

The thyroid gland develops in the embryo and descends from the base of the tongue to its final position in the neck, leaving a remnant of the pathway called the thyroglossal duct.

Thyroid hormone synthesis involves the use of iodide ions and tyrosine residues of thyroglobulin. The thyroid gland produces two primary hormones: T3 (triiodothyronine) and T4 (thyroxine).

T3 (triiodothyronine) and T4 (thyroxine) are produced from iodide and tyrosine. T3 is the more active form.

Thyroid hormone (T3) binds to specific receptors inside the nucleus of cells, leading to alterations in gene expression and protein synthesis. These changes ultimately influence cellular metabolism and various bodily functions.

Thyroid hormone plays a crucial role in regulating metabolism by influencing carbohydrate, fat, and protein metabolism. It increases basal metabolic rate and oxygen consumption.

The thyroid gland mostly releases T4, with plasma concentrations around 100 nmol/L. Although less potent, it's the major form circulating in the blood.

T3, though present at a much lower level (around 2 nM), packs a powerful punch, 2-10 times more active than its precursor T4.

Thyroid hormone regulates metabolic activity in all tissues except the brain, spleen, and testes. It has a significant impact on the basal metabolic rate, oxygen consumption, and heat production through the stimulation of the Na+-K+ ATPase.

Iodine is a vital micronutrient for thyroid hormone synthesis, obtained from food sources like seafood, dairy, and iodine-rich soils. The recommended daily intake varies based on age and physiological state.

Goiter is an enlargement of the thyroid gland, commonly found in areas with iodine deficiency. This occurs because the thyroid tries to compensate for insufficient iodine.

Cretinism is a severe form of hypothyroidism occurring due to iodine deficiency during pregnancy and early life, resulting in developmental delays, cognitive impairment, and physical stunting.

Thyroglobulin, a large protein synthesized by the thyroid follicular cells, serves as the foundation for thyroid hormone synthesis. It contains tyrosine residues essential for building these hormones.

Thyroid hormone synthesis involves several steps, including iodine trapping, oxidation/organification, coupling, endocytosis, proteolysis, and transport. These steps lead to the formation of T3 and T4.

T3 is the active form of thyroid hormone, regulating metabolism and various bodily functions. T4 acts as a precursor to T3, its conversion happening in peripheral tissues.

Thyroid hormone receptors are located inside target cells. When activated by T3, they bind to DNA, triggering gene transcription and leading to the production of proteins involved in various metabolic processes.

Thyroid hormone increases the rate of skeletal muscle contraction.

Thyroid hormone promotes the growth and maturation of bone, teeth, skin, hair follicles, and nails.

Thyroid hormone is crucial for normal brain development and function.

Thyroid hormone increases wakefulness, alertness, memory, and learning capacity.

Thyroid hormone stimulates growth of somatotrophs in the anterior pituitary gland, leading to increased growth hormone release.

A complex of thyroid hormone (T3) and its receptor binds to a specific DNA segment called the thyroid response element. This binding initiates a cascade of events, including the recruitment of coactivators and the release of corepressors, ultimately leading to the activation of gene transcription.

Thyroid hormone promotes the breakdown of fat, leading to increased mobilization of lipids from adipose tissue, enhancing β-oxidation, and ultimately reducing fat stores. This also reduces cholesterol levels, phospholipids, and triglycerides.

Thyroid hormone increases mitochondria production within cells, enhancing the activity of the Na+/K+ ATPase pump, which drives essential processes like energy production and cell function. It also increases oxygen consumption, protein synthesis, and ultimately the body's basal metabolic rate.

Thyroid hormone increases cardiac output and blood flow, likely due to increased oxygen demand. It also increases heart rate through a synergistic effect with catecholamines, and enhances heart strength, especially at slightly elevated levels.

A hormone secreted by the pituitary gland that stimulates the thyroid gland to produce and release thyroid hormones (T3 and T4).

The relationship between TSH and Free T4 is logarithmic and inverse. When Free T4 is high, TSH is low and vice versa. This is the body's way of maintaining a balance in thyroid hormone levels.

An autoimmune disease in which the immune system attacks the thyroid gland, causing it to produce excessive amounts of thyroid hormone (hyperthyroidism).

A form of hypothyroidism where the problem arises in the pituitary gland, leading to insufficient TSH production, resulting in reduced thyroid hormone secretion.

A condition where the thyroid gland is not able to produce enough thyroid hormone, often due to iodine deficiency, autoimmune disease, or other factors.