Thyroid Anatomy and Physiology Quiz

The anterior pituitary gland secretes six hormones: prolactin, TSH, GH, FSH, LH, and ACTH. Their release is controlled by hormones from the hypothalamus.

FSH and LH work together in females to regulate the ovarian cycle, including follicle growth, ovulation, and corpus luteum formation. In males, they control testicular functions.

Prolactin is the hormone responsible for stimulating milk production in lactating women.

The posterior pituitary gland doesn't produce hormones but stores and releases two hormones: ADH (vasopressin), which regulates water balance, and oxytocin, which plays a role in milk ejection and uterine contractions.

Oxytocin is released by the posterior pituitary and has two main functions: triggering milk ejection during breastfeeding and promoting uterine contractions during labor.

Oxytocin's effect on uterine contractions is mediated by the contraction of smooth muscle. This is achieved by activating Gq receptors, which leads to increased intracellular calcium and activation of myosin.

Oxytocin's release is triggered by sensory stimulation of the breast tissue (for milk ejection) or by pressure/thinning of the cervix (for uterine contractions) and not by central signals or negative feedback like other pituitary hormones.

The uterus becomes more sensitive to oxytocin towards the end of pregnancy due to an increase in gap junctions and oxytocin receptors, influenced by rising estrogen levels. This prepares the uterus for contractions.

ADH, also known as vasopressin, is released by the posterior pituitary and mainly functions to regulate water balance by increasing water reabsorption in the kidneys, leading to less urine production and maintaining blood osmolarity.

ADH release is primarily stimulated by increased ECF osmolarity, detected by osmoreceptors near the hypothalamus. Decreased blood pressure/volume also stimulates ADH release, detected by arterial and venous baroreceptors.

Expansion of a pituitary tumor can put pressure on the optic chiasm, leading to a specific type of vision loss affecting both sides of the visual field.

A condition caused by insufficient antidiuretic hormone (ADH) production or action, resulting in excessive water loss through urine.

A syndrome characterized by inappropriate release of ADH, leading to water retention, diluted blood, and hyponatremia.

A condition marked by elevated levels of prolactin in the blood, often caused by a lactotroph adenoma.

A type of pituitary tumor that mainly releases prolactin. It's the leading cause of hyperprolactinemia.

This condition occurs when the pituitary gland is unable to function normally. It is often an early sign of a pituitary tumor.

A condition where a pituitary tumor presses on the posterior pituitary stalk, interfering with the release of ADH, ultimately leading to diabetes insipidus.

A condition where the cavernous sinus is compressed by a pituitary tumor, affecting cranial nerves III, IV, and VI, leading to ophthalmoplegia and facial numbness.

A condition where the pituitary gland doesn't produce enough of one or more hormones, impacting various bodily functions.

Growth hormone deficiency in children leads to stunted growth, while adults experience reduced lean muscle mass, increased abdominal fat, and weakened bones.

FSH and LH deficiency disrupts the menstrual cycle and fertility in women and causes hypogonadism (reduced sex hormone production) in men.

ACTH deficiency leads to symptoms of hypocortisolism, but without mineralocorticoid deficiency.

TSH deficiency results in hypothyroidism, causing slow metabolism, fatigue, and weight gain.

PRL deficiency prevents milk production after childbirth.

The anterior pituitary gland controls the release of hormones by other glands through a feedback loop.

The hypothalamus regulates the anterior pituitary, which in turn controls the release of hormones by other glands like the thyroid, adrenals and gonads.

A condition where multiple nodules, often hyperplastic, replace a significant portion of the normal thyroid tissue. This is more common in regions with borderline iodine deficiency, as iodine deficiency can contribute to the development of goiters.

A type of thyroid disorder characterized by an enlarged thyroid gland. This can happen due to various reasons, including iodine deficiency, thyroiditis, or even tumors.

A condition where your thyroid gland is not producing enough thyroid hormones, leading to a slow metabolism. This can cause various symptoms like fatigue, weight gain, and cold intolerance.

A condition where your thyroid gland is overproducing thyroid hormones, leading to a fast metabolism. This can cause symptoms like weight loss, increased heart rate, and anxiety.

A condition that commonly develops with hypothyroidism due to the body's attempt to compensate for low thyroid hormone levels. The pituitary gland releases more TSH, stimulating the thyroid to grow larger even though it's not producing enough hormones.

A condition where the thyroid gland makes more T3 than T4. This is a response to low T3 and T4 levels caused by an iodine deficiency. The body is trying to maximize the available thyroid hormone.

This happens when a person is deficient in iodine, a crucial element for thyroid hormone synthesis. Without adequate iodine, the thyroid can't produce enough T3 and T4, leading to hypothyroidism.

A severe form of hypothyroidism that occurs in children. Lack of thyroid hormone during critical growth periods can lead to mental and physical developmental delays.

A small opening at the base of the tongue where the thyroid gland originates during embryonic development.

A temporary duct that connects the developing thyroid gland to the tongue. It normally disappears by the 10th week of gestation.

A remnant of the thyroglossal duct that extends superiorly from the isthmus of the thyroid gland. It's present in some individuals.

A rare condition where remnants of the thyroglossal duct persist, forming fluid-filled cysts in the neck. Approximately 7% of the population is affected.

The thyroid gland is located in the neck, anterior to the trachea and below the larynx. It consists of right and left lobes connected by the isthmus.

The thyroid gland is highly vascularized, meaning it has a rich blood supply. This is due to its role in hormone production.

A surgical procedure used to create an emergency airway through an incision between the thyroid and cricoid cartilages.

The thyroid gland is enclosed by a thin fibrous capsule that helps to protect it and anchor it to surrounding structures.

T3 and T4 are hydrophobic molecules, meaning they don't dissolve well in water-based environments like blood plasma.

T3 and T4 bind to transport proteins in the blood, like thyroxine-binding globulin (TBG), transthyretin, and albumin. This allows them to travel safely to target tissues.

T3 and T4 are released from thyroglobulin within the thyroid follicular cells.

T3 and T4 are carried in the bloodstream to target tissues, where they exert their effects.

The exact mechanism of how T3 and T4 leave the follicular cells and enter the bloodstream is not completely understood.

Most T3 and T4 in the blood are bound to transport proteins, which protects them from breakdown and extends their lifespan.

T3 is less tightly bound to transport proteins compared to T4, suggesting it might be more readily available to tissues.

Increased TSH secretion from the anterior pituitary stimulates thyroid hormone production by increasing the activity of various proteins involved in thyroid hormone synthesis.