MLT 103/104 Endocrinology Review

Comprehensive vocabulary flashcards covering the study of endocrinology, hormone types, glandular functions, associated disorders, and laboratory assay methods based on the lecture transcript.

Hormone

A chemical substance produced and secreted into the blood by an organ or tissue that has a specific effect on target tissue.

Target tissue

Tissue that is located some distance from the site of hormone production and responds to specific hormones.

Placenta

An organ that secretes estrogen, progesterone, and a wide variety of protein hormones, including Human Chorionic Gonadotrophin (HCG).

Human Chorionic Gonadotrophin (HCG)

A hormone produced by the embryo during pregnancy.

Three chemical types of hormones

Steroid, protein, and amine.

Steroidal hormones

Hormones synthesized from cholesterol that are lipid soluble, attached to carrier proteins, and have a plasma half-life of $60-100\,\text{min}$.

Peptide hormones

A subcategory of protein hormones synthesized as a prohormone; examples include insulin, glucagon, parathyroid hormone, growth hormone, and prolactin.

Glycoprotein Hormones

Hormones composed of alpha and beta chains; examples include FSH, LH, TSH, and HCG.

Alpha chain

The subunit of glycoprotein hormones (FSH, LH, TSH, and HCG) that is immunologically identical for all four.

Beta chain

The subunit of glycoprotein hormones that provides specificity for the hormone.

Catecholamines

Amines such as Epinephrine and Norepinephrine that behave like protein hormones and stimulate the sympathetic nervous system.

Thyroxine and Triiodothyronine

Amines that behave like steroid hormones.

Cyclic Adenosinemonophosphate (cAMP)

Acts as a "second messenger" by translating hormone binding into cellular action after an enzyme converts Adenosinetriphosphate.

Tropic hormone

A hormone that stimulates the synthesis of another specific hormone; examples include TRH, PRH, and PIH.

Negative feedback

A mechanism of control where the cessation of hormone synthesis is triggered by the hormone itself or the effected substance.

Hypothalamus

A portion of the brain located in the walls and floor of the third ventricle that stimulates the pituitary gland to release hormones.

Somatostatin

A hormone that inhibits the release of Growth Hormone (GH) and Thyroid Stimulating Hormone (TSH).

Dopamine

Also known as Prolactin Inhibiting Factor.

Sella turcica

A small cavity in the sphenoid bone of the skull where the anterior pituitary is located.

Direct effectors

Anterior pituitary hormones that act directly on tissues, such as GH and Prolactin.

Somatotropin

Another name for Growth Hormone (GH).

Acromegaly

A disorder associated with increased Growth Hormone (GH) in adults.

Prolactin

A hormone responsible for the initiation and maintenance of lactation; levels increase during sleep.

Panhypopituitarism

A deficiency of one or more hormones due to ischemia.

Neurohypophysis

Another name for the Posterior Pituitary, which stores ADH and Oxytocin.

Oxytocin

A hormone that causes contraction of uterine muscles during delivery and the ejection of milk during lactation.

Thyroxine-binding Globulin (TBG)

The major binding protein responsible for carrying thyroid hormones in the bloodstream.

Reverse T3 (rT3)

An inactive form of T3 that has no action on the cell and increases in nonthyroidal illness.

Calcitonin

A hormone that inhibits calcium resorption and lowers blood calcium and phosphorus.

Grave disease

A form of hyperthyroidism characterized by goiter and exophthalmic goiter (protruding eyes).

Parathyroid Hormone (PTH)

A hormone that regulates blood calcium concentration and vitamin D metabolism.

Adrenal Cortex

The outer part of the adrenal gland consisting of three layers: Zona Glomerulosa, Zona Fasciculata, and Zona Reticularis.

Aldosterone

A mineralcorticoid produced in the Zona Glomerulosa (G zone) responsible for electrolyte regulation.

Cortisol

A glucocorticoid produced in the Zona Fasciculata (F zone) that influences the metabolism of fats, carbohydrates, and proteins.

Cushing's Syndrome

A disorder associated with increased adrenocortical function.

Addison's Disease

A disorder associated with decreased adrenocortical function.

Pheochromocytoma

A benign tumor of the adrenal medulla.

Islets of Langerhans

Cells in the pancreas comprising alpha (glucagon), beta (insulin), and delta (somatostatin) types.

Estrodiol

The principle estrogen produced in the ovary.

Radioimmunoassay (RIA)

An immunologic assay utilizing radio-labeled hormones and anti-sera to measure patient hormone levels through competition for binding sites.