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Endocrine System

Composed of ductless glands that secrete chemical messengers, called hormones, into the bloodstream.

Hormones

Chemical messengers that enter the bloodstream and affect a variety of tissues and organs.

Target Organs

Tissues and organs on which hormones act.

Pituitary Gland

Located at the base of the brain just below the hypothalamus; known as the master gland.

Hypophysis

Another name for the pituitary gland, meaning growth located beneath or ventral to the hypothalamus.

Hypothalamus

Located below the thalamus in the brain; secretes releasing and inhibiting factors affecting the pituitary gland.

Infundibulum

A stalk connecting the hypothalamus to the pituitary gland; means funnel

Anterior Lobe

Also known as adenohypophysis; produces hormones that act indirectly on target organs.

Posterior Lobe

Also known as neurohypophysis; stores and secretes hormones that act directly on target organs.

Thyroid

Stimulating Hormone (TSH)

Adrenocorticotropic Hormone (ACTH)

Augments the growth and secretions of the adrenal cortex.

Follicle

Stimulating Hormone (FSH)

Gonadotropic Hormone

Hormones that have an affinity for gamete

Luteinizing Hormone (LH)

Augments ovulation and aids in the maintenance of pregnancy in females.

Corpus Luteum

The yellow body formed by luteinizing hormone transforming an ovarian follicle.

Anterior Pituitary Gland

Releases hormones that cause their target organ to produce a second hormone.

Posterior Pituitary Gland

Stores and secretes hormones that produce the desired effect directly in the target organ.

Adenohypophysis

Another name for the anterior lobe of the pituitary gland.

Neurohypophysis

Another name for the posterior lobe of the pituitary gland.

Stimuli

Factors from the hypothalamus that affect the secretion of hormones from the pituitary gland.

Growth

An increase in size or development, often regulated by hormones.

Interstitial cell

stimulating hormone

Prolactin

Augments milk secretion and influences maternal behavior; also known as lactogenic hormone or luteotropin; sometimes abbreviated LTH.

Growth hormone

Accelerates body growth; abbreviated GH; also known as somatotropin; sometimes abbreviated STH.

Melanocyte

stimulating hormone

Antidiuretic hormone

Maintains water balance in the body by augmenting water reabsorption in the kidneys; abbreviated ADH; also known as vasopressin.

Oxytocin

Stimulates uterine contractions during parturition and milk letdown from the mammary ducts.

Thyroid gland

A butterfly

Triiodothyronine

One of the thyroid hormones that regulates metabolism; abbreviated T3.

Thyroxine

One of the thyroid hormones that regulates metabolism; abbreviated T4.

Calcitonin

Thyroid hormone that promotes the absorption of calcium from blood into bones (lowers blood calcium and raises bone calcium levels).

Parathyroid glands

Four glands located on the surface of the thyroid gland that secrete parathyroid hormone (PTH).

Parathyroid hormone

Helps regulate blood calcium and phosphorus levels; increases blood calcium levels by reducing bone calcium levels.

Adrenal glands

Two small glands located cranial to each kidney that regulate electrolytes, metabolism, sexual functions, and the body's response to injury.

Adrenal cortex

Outer portion of the adrenal gland.

Adrenal medulla

Inner portion of the adrenal gland.

Corticosteroids

Substances produced by the adrenal cortex.

Mineralocorticoids

Group of corticosteroids that regulates electrolyte and water balance by affecting ion transport in the kidney.

Aldosterone

The principal mineralocorticoid that regulates sodium and potassium.

Glucocorticoids

Group of corticosteroids that regulates carbohydrate, fat, and protein metabolism; resistance to stress; and immunologic functioning.

Hydrocortisone

An example of a glucocorticoid that regulates carbohydrate, fat, and protein metabolism.

Cortisol

Another name for hydrocortisone, which regulates carbohydrate, fat, and protein metabolism.

Androgens

Group of corticosteroids that aids in the development and maintenance of male sex characteristics.

Anabolic Steroids

Synthetic medications similar in structure to testosterone that are used to increase strength and muscle mass.

Anabolism

The process of building up, opposite of catabolism.

Catabolism

The process of breaking down.

Epinephrine

Catecholamine that stimulates the sympathetic nervous system and increases blood pressure, heart rate, and blood glucose.

Adrenaline

Another name for epinephrine.

Vasopressor

A substance that stimulates blood vessel contraction and increases blood pressure.

Norepinephrine

Catecholamine that stimulates the sympathetic nervous system and increases blood pressure, heart rate, and blood glucose.

Noradrenaline

Another name for norepinephrine.

Pancreas

An aggregation of cells located near the proximal duodenum that has both exocrine and endocrine functions.

Islets of Langerhans

Specialized cells in the pancreas that secrete hormones to help regulate blood glucose.

Insulin

A hormone secreted by the pancreas in response to elevated plasma glucose.

Insulin Receptors

Cell membrane receptors that insulin combines with to allow glucose to enter the cell.

Glucose

A simple sugar that is an important energy source in living organisms.

Insulin

Hormone that decreases blood glucose levels by transporting blood glucose into body cells or into storage as glycogen.

Insulin receptors

Proteins on cell membranes that insulin binds to, activating glucose transporters allowing glucose to enter the cell.

Glycogen

The main carbohydrate storage unit in animals.

Glucagon

Hormone that increases blood glucose levels by breaking down glycogen to glucose.

Thymus

A gland predominant in young animals located near midline in the cranio

Thymosin

Hormone that augments maturation of T

Pineal gland

An aggregation of cells located in the central portion of the brain, involved in the secretion of serotonin and melatonin.

Melatonin

Hormone that controls circadian rhythm and reproductive timing.

Circadian rhythm

Events occurring within a 24

Gonads

Gamete

Gamete

A sex cell.

Estrogen

Hormone that aids in the development of secondary sex characteristics and regulates ovulation in females.

Progesterone

Hormone that aids in the maintenance of pregnancy.

Testosterone

Hormone that augments the development of secondary sex characteristics.

ACTH stimulation test

Blood analysis for cortisol levels after administration of synthetic adrenocorticotropic hormone; used to differentiate pituitary

Assays

Laboratory technique used to determine the amount of a particular substance in a sample.

dexamethasone suppression test

blood analysis for cortisol levels after administration of synthetic glucocorticoid (dexamethasone); used to differentiate pituitary

radioactive iodine uptake test

analysis of thyroid function after radioactive iodine has been given orally or intravenously. Absorption of the radioactive iodine is measured with a counter for a specific time period.

thyroid stimulation test

blood analysis for thyroid hormone levels after administration of synthetic thyroid

acromegaly

enlargement of the extremities caused by excessive secretion of growth hormone after puberty.

adrenopathy

disease of the adrenal glands.

aldosteronism

disorder caused by excessive secretion of aldosterone by the adrenal cortex, resulting in electrolyte imbalance.

diabetes insipidus

insufficient antidiuretic hormone production or the inability of the kidneys to respond to ADH stimuli; abbreviated DI.

diabetes mellitus

metabolic disorder of inadequate secretion of insulin or recognition of insulin by the body, resulting in increased urination, drinking, and weight loss; abbreviated DM.

ketoacidosis

abnormal condition of low pH accompanied by ketones (by

endocrinopathy

disease of the hormone

gynecomastia

condition of excessive mammary development in males.

hyperadrenocorticism

disorder caused by excessive adrenal cortex production of glucocorticoid, resulting in increased urination, drinking, and redistribution of body fat; also called Cushing's disease.

hypercrinism

condition of excessive gland secretion.

hyperglycemia

abnormally elevated blood glucose.

hypergonadism

abnormal condition of excessive hormone secretion by the sex glands (ovaries in females; testes in males).

hyperinsulinism

disorder of excessive hormone that transports blood glucose to body cells.

hyperparathyroidism

abnormal condition of excessive parathyroid hormone secretion resulting in hypercalcemia.

hyperpituitarism

condition of excessive secretion of the pituitary gland.

hyperthyroidism

condition of excessive thyroid hormone.

hyperthyroidism

Signs include increased metabolic rate, weight loss, polyuria, and polydipsia.

hypoadrenocorticism

Disorder caused by deficient adrenal cortex production of glucocorticoid, resulting in weakness, vomiting, and weight loss; also called Addison's disease.

hypocrinism

Condition of deficient gland secretion.

hypoglycemia

Abnormally low blood glucose; signs include shakiness, anxiety, confusion, convulsions, seizures, and, if untreated, loss of consciousness.

hypogonadism

Abnormal condition of deficient hormone secretion by the sex glands (ovaries in females; testes in males).

hypoparathyroidism

Abnormal condition of deficient parathyroid hormone secretion resulting in hypocalcemia.

hypocalcemia

Abnormally low levels of blood calcium.

hypercalcemia

Abnormally high blood calcium levels.

hypophysitis

Inflammation of the pituitary gland.