Thyroid Anatomy and Function Quiz

The thyroid gland is located in the neck, below the thyroid cartilage, behind the strap muscles.

The thyroid gland has two lobes, joined by an isthmus (a connecting bridge), and sits below the cricoid cartilage.

The thyroid gland is composed of two lobes, each consisting of follicles, which are spherical structures surrounded by a single layer of follicular cells that produce thyroid hormone.

The thyroid cartilage (also known as the Adam's apple) is a prominent cartilage in the neck that forms the front part of the larynx, or voice box.

The cricoid cartilage is a ring-shaped cartilage in the neck that forms the lower part of the larynx, below the thyroid cartilage.

A protein complex that binds to specific DNA sequences called thyroid response elements, initiating the process of transcription.

The Thyroid Hormone-Receptor Complex interacts with co-activators and co-repressors to start or stop gene transcription, which leads to changes in protein synthesis.

Thyroid hormone plays a role in stimulating the breakdown of fats, increasing the use of free fatty acids, and decreasing cholesterol levels.

Thyroid hormone influences various metabolic processes, including increased glucose uptake, enhanced glycolysis, enhanced gluconeogenesis, and increased insulin secretion.

Thyroid hormone helps regulate energy production and utilization. It increases mitochondria number, oxygen consumption, protein synthesis, and the overall basal metabolic rate.

Iodide trapping is the first step in thyroid hormone synthesis, where iodide ions from the bloodstream are actively transported into thyroid follicular cells against their concentration gradient.

The sodium-iodide symporter (NIS) is a protein embedded in the basal membrane of thyroid follicular cells. It uses the energy of the sodium gradient to transport iodide ions from the bloodstream into the cell.

Pendrin is a protein located in the apical membrane of thyroid follicular cells. Its role is to transport iodide ions from the cell into the colloid, the fluid-filled space within the follicle.

Thyroid peroxidase (TPO) is an enzyme crucial for the oxidation and organification of iodide. It catalyzes the conversion of iodide to iodine and its subsequent attachment to tyrosine residues of thyroglobulin.

Pendred syndrome is a genetic disorder that results in defective Pendrin function, leading to iodide deficiency in the thyroid gland and congenital hypothyroidism.

The thyroglossal duct is a transient structure that connects the developing thyroid gland to the tongue during embryonic development.

The thyroid gland begins its journey high in the neck, near the tongue, and eventually migrates down to its final position in the lower neck, anterior to the trachea.

It occurs when the thyroglossal duct doesn't completely disappear, and instead persists as a cyst (fluid-filled sac) in the neck.

The thyroglossal duct normally vanishes by 7-10 weeks of gestation, leaving no trace behind.

Ectopic thyroid tissue refers to thyroid tissue that develops in an abnormal location, often along the path of the thyroglossal duct.

Lingual thyroid is a rare condition where thyroid tissue develops in the tongue, a common location for ectopic thyroid tissue.

T3 (triiodothyronine) and T4 (thyroxine) are the primary thyroid hormones synthesized by the thyroid gland and are essential for regulating metabolism.

Reverse T3 (rT3) is a biologically inactive form of thyroid hormone. It's important to note it's not directly involved in regulating metabolism.

T4 is converted to T3 by deiodinase enzyme in peripheral tissues, particularly the liver and kidneys. T3 is much more potent than T4, roughly 4 times stronger.

T3 is considered the main active form of thyroid hormone. T4 is considered a prohormone, meaning it needs conversion to T3 to become active.

The outer-ring monodeiodinase enzyme converts T4 to active T3. While the inner-ring monodeiodinase converts T4 to the inactive form, rT3.

The thyroid gland is responsible for releasing T4, while the peripheral tissues convert it to T3. Most T3 in circulation comes from peripheral conversion, only about 20% comes directly from the thyroid gland.

When cellular T3 levels are sufficient, the cell switches to the inner-ring enzyme, producing inactive rT3. This helps regulate the amount of active T3 in the cell.

The hypothalamus, pituitary gland and thyroid gland are involved in regulating the production of thyroid hormones. This involves a negative feedback loop.

The hypothalamus releases thyrotropin-releasing hormone (TRH) which stimulates the pituitary gland to produce thyroid-stimulating hormone (TSH). TSH then stimulates the thyroid gland to release thyroid hormones.

High levels of thyroid hormones in the blood inhibit the release of TRH and TSH, thus reducing thyroid hormone production. Low levels of thyroid hormones stimulate TRH and TSH release, resulting in increased thyroid hormone production.

Increased thyroid hormone levels have a negative feedback effect on TSH release. Conversely, decreased thyroid hormone levels stimulate TSH release.

Thyroid stimulating hormone (TSH) is a glycoprotein produced by the anterior pituitary. It plays a crucial role in regulating the growth, development and function of the thyroid gland.

This is a condition where the body raises the level of glucose in the blood by breaking down proteins, often due to excess levels of certain hormones. This can be detrimental as it uses protein reserves for energy instead of carbs.

The respiratory system increases its activity, meaning you breathe faster and deeper. This is often a response to increased metabolism and the need for more oxygen.

Thyroid hormone plays a key role in developing the central nervous system in the fetus and young children. Without it, the nervous system might not develop completely.

Thyroid hormone is essential for proper mental function. It enhances focus, memory, and learning abilities, making it easier to concentrate and store information.

Thyroid hormone helps regulate your mood. It's linked to emotional stability and a balanced emotional state. A lack of it might contribute to mood swings.

Pendrin is a protein found on the apical membrane of thyroid follicular cells. Its role is to move iodide ions (I-) from the cell into the colloid, the fluid-filled space within the follicles where thyroid hormone is synthesized.

Thyroid peroxidase (TPO) is an enzyme essential for the oxidation and organification of iodide. It converts iodide ions (I-) to iodine (I2) and then couples it to tyrosine residues on the thyroglobulin protein.

T4 (thyroxine) is the primary thyroid hormone secreted by the gland, but T3 (triiodothyronine) is 2-10 times more biologically active.

T4 has a longer half-life than T3, meaning it stays in the bloodstream longer.

Most of the circulating T4 and T3 in the bloodstream are bound to carrier proteins, specifically TBG (thyroxine-binding globulin), TBPA (thyroxine-binding prealbumin), and albumin.

T4 is the precursor to T3, undergoing conversion in peripheral tissues by deiodinase enzymes. This conversion process is essential for producing the biologically most active form of the hormone.

Free thyroid hormones (not bound to carrier proteins) are the active forms responsible for affecting target tissues. Their concentration is tightly regulated.

The functional unit of the thyroid gland, composed of follicular cells surrounding a lumen filled with colloid.

These cells are responsible for synthesizing and releasing thyroid hormones. They line the lumen of the thyroid follicle.

This is a viscous fluid found in the lumen of the thyroid follicle. It contains thyroglobulin, a protein that binds to thyroid hormones.

These are blood vessels that supply nutrients to the thyroid gland and transport thyroid hormones to other parts of the body.

This is the nervous system that influences the synthesis and secretion of thyroid hormones.

These are small structures near the thyroid follicle that produce calcitonin, a hormone involved in calcium regulation.

The thyroid gland develops from the thyroglossal duct, a diverticulum appearing on the floor of the pharynx during embryonic development.

The thyroid gland descends during development and forms two lobes, connected by an isthmus. This occurs around the 7th-8th week of gestation.

During embryonic development, a passage called the thyroglossal duct connects the developing thyroid gland to the tongue. However, this duct typically disappears completely by 7-10 weeks of gestation.

If the thyroglossal duct doesn't entirely disappear, a fluid-filled sac called a thyroglossal duct cyst can form in the neck. It's usually located near the midline, just below the hyoid bone.

Thyroid tissue can sometimes develop in locations other than its normal position. This can occur along the path of the thyroglossal duct, including the tongue and even the chest.

A rare condition where thyroid tissue develops in the tongue. It's a common location for ectopic thyroid tissue.

The primary thyroid hormones, T3 (triiodothyronine) and T4 (thyroxine), are produced by the thyroid gland and play a crucial role in regulating metabolism.

Reverse T3 (rT3) is a biologically inactive form of thyroid hormone. Unlike T3 and T4, it doesn't have a major role in regulating metabolism.

Iodide is trapped in thyroid follicular cells by active transport. This is the first step in thyroid hormone synthesis.

Thyroid hormone is crucial for the development of the central nervous system (CNS) in fetuses and young children. It helps create and mature the brain and nervous system.

Thyroid hormone increases the brain's ability to learn and retain information. It enhances alertness, focus, and overall mental function.

Thyroid hormone is involved in regulating emotional balance and stability. It helps maintain a healthy emotional state, making you feel more grounded and less prone to mood swings.

Thyroid hormone is essential for increasing the speed and strength of nerve impulses. It makes your nerve signals travel faster and more efficiently.

Thyroid hormone plays a role in regulating your core body temperature. It helps maintain a balanced temperature by increasing your metabolic rate and how much energy your body burns.

The conversion of inactive T4 to active T3, primarily in the liver and kidneys.

A process of converting T4 into either active T3 or inactive rT3 that occurs within target tissues.

T4 acts as a precursor that is transformed into the more potent T3.

The hypothalamus, pituitary gland, and thyroid gland are involved in regulating the production and level of thyroid hormones. This involves a feedback loop where high levels of thyroid hormones inhibit further production.

The thyroid gland, pituitary gland, and hypothalamus are involved in a negative feedback loop, where high levels of thyroid hormones suppress the production and release of TSH.

Thyroid-stimulating hormone (TSH) is a glycoprotein synthesized in the anterior pituitary gland. It stimulates the thyroid gland to produce and release thyroid hormones.

The mechanism by which thyroid hormone affects gene expression and metabolism. It involves binding to thyroid receptors which then regulate gene transcription.

Increased oxygen consumption in the body, often due to thyroid hormone stimulation of metabolism, leading to increased energy expenditure.

A condition where the body increases the level of glucose in the blood by breaking down proteins. This can be detrimental to health.