Thyroid and Parathyroid Glands

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Questions and Answers

Which formula is used to calculate the volume of each lobe of the thyroid gland?

Ellipsoid formula (correct)

Sphere formula

Cylinder formula

Cuboid formula

What is the appearance of the esophagus compared to the thyroid gland in a transverse section?

Hyperechoic walls and hyperechoic mucosa

Hypoechoic walls and hyperechoic mucosa (correct)

Hypoechoic walls and hypoechoic mucosa

Hyperechoic walls and hypoechoic mucosa

What is the material that fills the thyroid follicles called?

Colloid (correct)

Thyroid hormone

Calcitonin

Thyroxine

Which arteries supply the thyroid gland with blood?

Superior thyroid artery and inferior thyroid artery Signup and view all the answers

Describe the location of the parathyroid gland.

Posterior to the thyroid gland Signup and view all the answers

What are the measurements of the parathyroid gland?

5.0-7.0 mm in length, 1.0-2.0 mm in height, 3.0-4.0 mm in width Signup and view all the answers

What is the echogenicity of the parathyroid glands compared with the thyroid gland?

Isoechoic Signup and view all the answers

What hormone is secreted by the parathyroid gland?

Parathormone (PTH) Signup and view all the answers

Which arteries supply the parathyroid glands?

Superior and inferior thyroid arteries Signup and view all the answers

What is the most common cause of thyroid gland enlargement?

Iodine deficiency Signup and view all the answers

Which hormones does the thyroid gland secrete?

Triiodothyronine (T3), thyroxine (T4), and calcitonin Signup and view all the answers

How is the thyroid hormone secretion regulated?

Controlled by the pituitary gland which secretes TSH Signup and view all the answers

What are the lobes of the thyroid gland?

Right and left lobes, connected by the isthmus Signup and view all the answers

What structures border the thyroid gland anteriorly, posteriorly, and laterally?

Strap muscles, Longus colli muscle, Trachea, Common carotid artery Signup and view all the answers

What are the measurements of the thyroid gland and the isthmus in adults?

Each lobe: 40-60 mm length x 15-20 mm width x 13-18 mm thickness (AP), Isthmus: 2-6 mm AP diameter Signup and view all the answers

How is the echogenicity and vascularity of the thyroid gland described?

Uniformly echogenic, with medium- to high-level echoes Signup and view all the answers

What hormones does the parathyroid gland secrete?

Parathyroid hormone (PTH) Signup and view all the answers

What is the function of parathyroid hormone (PTH)?

Increase blood calcium level Signup and view all the answers

How many lobes does the parathyroid gland have?

Four Signup and view all the answers

Which hormones does the parathyroid gland secrete?

Parathyroid hormone (PTH) Signup and view all the answers

Describe the location of the parathyroid gland.

Posterior to the thyroid gland Signup and view all the answers

What is the appearance of the esophagus compared to the thyroid gland in a transverse section?

Hypoechoic Signup and view all the answers

What are the measurements of the parathyroid gland?

2 to 6 mm AP diameter Signup and view all the answers

How is the echogenicity and vascularity of the thyroid gland described?

Uniformly echogenic, with medium- to high-level echoes Signup and view all the answers

What are the functions of the thyroid gland's hormones?

Stimulates cellular metabolism Signup and view all the answers

What are the lobes of the thyroid gland?

Right lobe and left lobe Signup and view all the answers

What structures border the thyroid gland anteriorly, posteriorly, and laterally?

Strap muscles anteriorly, Longus colli muscle posteriorly, Trachea laterally Signup and view all the answers

Which formula is used to calculate the volume of each lobe of the thyroid gland?

Ellipsoid formula with a correction factor Signup and view all the answers

What is the appearance of the esophagus compared to the thyroid gland in a transverse section?

Hypoechoic walls and hyperechoic mucosa Signup and view all the answers

What is the material that fills the thyroid follicles called?

Colloid Signup and view all the answers

Which arteries supply the thyroid gland with blood, and where do they originate from?

Superior thyroid artery from the ECA, and inferior thyroid artery from the thyrocervical trunk Signup and view all the answers

Describe the location of the parathyroid gland.

Two superior parathyroid glands lie posterior to superior poles of thyroid; two inferior lie posterior to inferior poles of the thyroid gland Signup and view all the answers

What are the measurements of the parathyroid gland?

5.0-7.0 mm in length, 1.0-2.0 mm in height, 3.0-4.0 mm in width Signup and view all the answers

What is the echogenicity of the parathyroid glands compared with the thyroid gland?

Similar in echogenicity to thyroid, and are not generally identified with ultrasound unless they are abnormal Signup and view all the answers

What hormone is secreted by the parathyroid gland? Explain the function of the hormone.

Parathormone (PTH). It increases blood calcium level by three mechanisms: increasing the breakdown of bone matrix to release the calcium to the blood, increasing the reabsorption of calcium from the renal tubules to the blood, and increasing the absorption of calcium from the intestines to the blood via vitamin D Signup and view all the answers

Which muscles are located anterior and lateral to the thyroid gland?

Strap muscles Signup and view all the answers

Which muscle is seen posterior to the thyroid gland?

Longus colli muscle Signup and view all the answers

What forms the lateral border of the thyroid gland?

Trachea Signup and view all the answers

Which structures are posterolateral to the thyroid gland?

CCA and IJV Signup and view all the answers

How are nodules classified?

Hot or cold nodules Signup and view all the answers

What is a hot nodule?

A nodule that traps an excessive amount of isotope and is hyperfunctioning Signup and view all the answers

What is a cold nodule?

A nodule that does not absorb isotope and demonstrates an area of decreased or absent activity Signup and view all the answers

Which veins drain into the IJV?

Superior & Middle thyroid vein Signup and view all the answers

What is the function of the IJV?

B. Drains blood from the head and neck region Signup and view all the answers

Which veins drain into the brachiocephalic veins?

Inferior thyroid veins Signup and view all the answers

What is the function of the thyroid gland's hormones?

Metabolism regulation Signup and view all the answers

What is the appearance of the thyroid gland compared to the esophagus in a transverse section?

Hypoechoic compared to the esophagus Signup and view all the answers

Where is the parotid gland located?

In the retromandibular fossa Signup and view all the answers

What is the function of the parotid gland?

Production of saliva Signup and view all the answers

Which is the largest salivary gland?

Parotid gland Signup and view all the answers

Which hormone stimulates the kidneys to convert vitamin D into its active form?

A. PTH Signup and view all the answers

How does PTH regulate calcium levels in the extracellular fluid?

A. By increasing the release of calcium from bones Signup and view all the answers

What is the main function of parathyroid hormone (PTH)?

A. Regulating calcium and phosphorous levels in extracellular fluid Signup and view all the answers

Which of the following is NOT a function of the parotid glands?

Produce PTH Signup and view all the answers

What is the role of the parotid glands in the digestion process?

Produce saliva that moistens the food Signup and view all the answers

How do the parotid glands facilitate swallowing?

By producing saliva that helps in lubricating the food Signup and view all the answers

Where is TSH (Thyroid Stimulating Hormone) produced?

Anterior pituitary gland Signup and view all the answers

What is the role of TSH in the body?

Regulates metabolism, growth, and development Signup and view all the answers

Which endocrine gland does TSH primarily target?

Thyroid gland Signup and view all the answers

Which cells are the primary source for the production of parathyroid hormone (PTH)?

Chief cells Signup and view all the answers

Where are the chief cells located?

Parathyroid glands Signup and view all the answers

What is the role of parathyroid hormone (PTH) in the body?

Regulating calcium and phosphate levels Signup and view all the answers

Which thyroid condition is associated with a deficiency in iodine?

Goiter Signup and view all the answers

What is the function of parathyroid hormone (PTH) in the body?

Regulating blood calcium levels Signup and view all the answers

Which arteries supply the thyroid gland with blood?

Carotid arteries Signup and view all the answers

Which hormone is responsible for increasing blood calcium levels and decreasing blood phosphorus levels?

B. PTH Signup and view all the answers

Which gland secretes parathyroid hormone (PTH)?

D. Parathyroid gland Signup and view all the answers

What is the role of parathyroid hormone (PTH) in the body?

B. Regulating blood calcium and phosphorus levels Signup and view all the answers

Study Notes

Thyroid Gland Anatomy

The volume of each lobe of the thyroid gland is calculated using the formula: Volume = Length × Width × Thickness × 0.479.
In a transverse section, the esophagus appears posterior to the thyroid gland.
Thyroid follicles are filled with colloid material, which is essential for hormone production.

Blood Supply

The thyroid gland receives blood supply primarily from the superior thyroid artery (branch of the external carotid artery) and the inferior thyroid artery (branch of the subclavian artery).
The parathyroid glands are typically supplied by the inferior thyroid arteries.

Parathyroid Gland Characteristics

Parathyroid glands are usually located on the posterior surface of the thyroid gland.
Average measurements of the parathyroid gland are approximately 4-6 mm in length and 2-4 mm in width.
Echogenicity of the parathyroid gland is typically lower compared to the thyroid gland, making them less visible on ultrasound.

Hormonal Functions

The primary hormone secreted by the parathyroid gland is parathyroid hormone (PTH).
PTH plays a critical role in regulating calcium levels in the blood and promotes bone resorption.
The thyroid gland secretes hormones such as T3 (triiodothyronine) and T4 (thyroxine), which regulate metabolism.

Structural Relationships

Anteriorly, the thyroid gland is bordered by the strap muscles; laterally by the common carotid artery, and posteriorly by the trachea and esophagus.
Typical measurements of the thyroid gland in adults are approximately 4-6 cm in length and 1-2 cm in width for each lobe, with the isthmus measuring 4-6 mm.

Echogenicity and Vascularity

The thyroid gland generally exhibits a homogeneous echogenicity with increased vascularity, visible on Doppler ultrasound.

Nodules and Conditions

Thyroid nodules are classified based on their functionality; "hot nodules" take up more radioactive iodine and are usually benign, while "cold nodules" do not and may require further evaluation for malignancy.
The most common cause of thyroid enlargement (goiter) is iodine deficiency.

Other Endocrine Functions

Thyroid Stimulating Hormone (TSH) is produced by the pituitary gland and primarily targets the thyroid gland to stimulate the production of T3 and T4.
The parotid gland, the largest salivary gland, is responsible for producing saliva to aid in digestion and facilitate swallowing.

Calcium Regulation

TSH regulates thyroid hormone secretion, which is crucial for metabolic processes.
PTH raises blood calcium levels and decreases blood phosphorus levels by increasing intestinal absorption of calcium and promoting renal reabsorption of calcium.
Chief cells in the parathyroid gland are responsible for the production of parathyroid hormone (PTH).

Iodine Deficiency

Iodine deficiency can lead to hypothyroidism and is associated with conditions like goiter.

Anatomy and Functions of Salivary Glands

Parotid glands are located near the ear and play a significant role in the oral phase of digestion. They facilitate swallowing by moistening food.

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Description

Test your knowledge on the anatomy and physiology of the thyroid and parathyroid glands. Answer questions about the hormones secreted by the thyroid gland and their functions, including the role of calcitonin in regulating calcium levels.